Fishes

22 pages, 8096 KB

Open AccessEditor’s ChoiceArticle

Detecting Natural Reproduction Following Reintroduction Using Complementary Genetic Approaches in the Endangered Zingel asper

by Simon P. Barbary, Mickaël Béjean, Jérôme G. Prunier, Rémi Grenier and Vincent Dubut

Fishes 2026, 11(8), 433; https://doi.org/10.3390/fishes11080433 - 23 Jul 2026

Viewed by 989

Abstract

Reintroduction programmes are increasingly used to restore threatened freshwater fishes, yet evaluating their success remains challenging during the early stages of population establishment. Genetic monitoring is commonly used to assess diversity but rarely provides direct evidence of natural reproduction. Here, we investigated natural [...] Read more.

Reintroduction programmes are increasingly used to restore threatened freshwater fishes, yet evaluating their success remains challenging during the early stages of population establishment. Genetic monitoring is commonly used to assess diversity but rarely provides direct evidence of natural reproduction. Here, we investigated natural reproduction following reintroduction in the endangered Zingel asper, a benthic fish endemic to the Rhône River basin. Between 2006 and 2015, more than 25,000 captive-bred individuals from two source populations were released into the Drôme River (France). Using 54 microsatellite loci, we assessed genetic diversity, effective population size, relatedness and inbreeding, reconstructed parentage relationships, and evaluated admixture among source lineages through hybrid assignment analyses. Wild source populations differed markedly in genetic diversity and effective population size, whereas captive propagation reduced genetic diversity and increased relatedness and inbreeding. Despite these effects, the reintroduced population exhibited higher allelic richness than any captive cohort. Parentage analyses provided direct genetic evidence of natural reproduction by identifying individuals whose genetic origin could not be explained by the captive breeding pedigree. Hybrid assignment analyses independently confirmed admixture between source lineages. These results show how complementary genetic approaches can provide early evidence of reintroduction success and support adaptive management of threatened fish populations. Full article

(This article belongs to the Section Biology and Ecology)

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17 pages, 1771 KB

Open AccessEditor’s ChoiceArticle

No-Take Protection Supports Richer Fish Assemblages at a Grey Nurse Shark (Carcharias taurus) Aggregation Site

by Lea T. Mamo, Euan J. Provost, Alejandro Tagliafico and Brendan P. Kelaher

Fishes 2026, 11(7), 408; https://doi.org/10.3390/fishes11070408 - 9 Jul 2026

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Abstract

No-take Marine Protected Areas (MPAs) are widely used to conserve biodiversity and rebuild fish populations, but their ecological benefits can vary among locations and habitats. Cod Grounds Marine Park protects a key aggregation site for the critically endangered grey nurse shark (Carcharias [...] Read more.

No-take Marine Protected Areas (MPAs) are widely used to conserve biodiversity and rebuild fish populations, but their ecological benefits can vary among locations and habitats. Cod Grounds Marine Park protects a key aggregation site for the critically endangered grey nurse shark (Carcharias taurus), providing an opportunity to assess whether no-take protection is associated with enhanced fish assemblages and prey availability. Fish communities were surveyed using baited remote underwater video systems (BRUVs) at protected and nearby fished reefs across seven sampling periods between 2015 and 2018. Protected reefs supported different assemblages, as well as approximately 9% more species and 50% greater fish abundance than fished reefs. Species identified as potential grey nurse shark prey were approximately 55% more abundant inside the reserve, and grey nurse sharks were recorded exclusively within the marine park. In contrast, water temperature and variation in compliance effort explained little variation in fish assemblage metrics. These findings highlight the ecological value of protecting key aggregation habitat for grey nurse sharkss by supporting richer reef fish communities and greater prey availability. Full article

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19 pages, 10220 KB

Open AccessEditor’s ChoiceArticle

Neuroimmune Interactions in the Intestine of Goldfish (Carassius auratus): Insights into Enteric Neurons and Immune Cell Organization

by Doaa M. Mokhtar, Eugenia Rita Lauriano, Marialuisa Aragona, Hailah M. Almohaimeed, Nashmiah S. Alshammari, Anthea Miller, Tahani A. Al-Matrafi, Maria Cristina Guerrera, Giorgia Pia Lombardo, Adriana Nunnari and Giacomo Zaccone

Fishes 2026, 11(6), 359; https://doi.org/10.3390/fishes11060359 - 16 Jun 2026

Cited by 1 | Viewed by 513

Abstract

Neuroimmune interactions in the intestine are essential for maintaining tissue homeostasis, yet they remain poorly understood in teleost fish. This study investigated the structural and cellular organization of enteric neurons and immune cells in the intestine of goldfish (Carassius auratus) using [...] Read more.

Neuroimmune interactions in the intestine are essential for maintaining tissue homeostasis, yet they remain poorly understood in teleost fish. This study investigated the structural and cellular organization of enteric neurons and immune cells in the intestine of goldfish (Carassius auratus) using semithin histology, transmission electron microscopy (TEM), and confocal immunofluorescence. Histological observations revealed a well-organized epithelium composed of enterocytes and goblet cells, with numerous lymphocytes located in the basal epithelium. Prominent gut-associated lymphoid tissue (GALT) was identified in both scattered and aggregated forms within the lamina propria and submucosa. Macrophages were widely distributed throughout all intestinal layers and were consistently found in close proximity to enteric neurons and nerve fibers. Ultrastructural analysis confirmed direct contacts between macrophages and neuronal elements. These macrophages exhibited typical phagocytic features, including lysosomes, vacuoles, and engulfed material, particularly in association with myenteric nerve fibers. Immunofluorescence analysis revealed strong expression of toll-like receptor 2 (TLR2) and major histocompatibility complex class II (MHC II) in macrophages and enterocytes, suggesting an active role in antigen recognition. Langerin-positive dendritic-like cells were identified in the submucosa, while CD4-positive lymphocytes showed partial colocalization with serotonin (5-HT). S100-positive cells also exhibited partial overlap with 5-HT, and goblet cells demonstrated serotonin immunoreactivity. In addition, inducible nitric oxide synthase (iNOS) colocalized with TLR2 in submucosal immune cells. These findings demonstrate a close structural and functional association between enteric neurons and immune cells, highlighting an integrated neuroimmune network in the goldfish intestine. Full article

(This article belongs to the Special Issue Molecular Mechanisms of the Non-Specific Immunity of Fish When Responding to Pathogen Infections)

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17 pages, 4109 KB

Open AccessEditor’s ChoiceArticle

Annual Fecundity of European Anchovy: A Case Study in the North Aegean Sea (Eastern Mediterranean)

by Eudoxia Schismenou, Konstantinos Markakis and Stylianos Somarakis

Fishes 2026, 11(6), 318; https://doi.org/10.3390/fishes11060318 - 26 May 2026

Viewed by 1935

Abstract

Egg production estimates are key indicators of stock reproductive potential. In indeterminate spawners, annual fecundity cannot be estimated prior to the spawning season and, instead, requires quantification of batch fecundity and spawning frequency along the entire spawning period. In the present study, we [...] Read more.

Egg production estimates are key indicators of stock reproductive potential. In indeterminate spawners, annual fecundity cannot be estimated prior to the spawning season and, instead, requires quantification of batch fecundity and spawning frequency along the entire spawning period. In the present study, we provide the first estimate of annual fecundity of European anchovy (Engraulis encrasicolus) in the Mediterranean Sea (Northeast Aegean Sea). Monthly samples collected throughout 2019 were used to delimit the duration of the spawning season and provide monthly estimates of batch fecundity and spawning frequency. Furthermore, monthly variations in stage-specific relative oocyte numbers were examined using stereology and oocyte packing density theory. Spawning activity occurred mainly from April to September and spawning frequency of spawning capable and actively spawning females ranged from 0.25 to 0.35. Due to the limited number of females with hydrated oocytes, batch fecundity was assumed to exhibit seasonal stability. The relative number of vitellogenic oocytes did not change significantly along the spawning period which supported this assumption. The calculated total number of spawnings per year was 55 and relative annual fecundity was ~20,000 eggs g⁻¹. These findings provide essential input for daily egg production method applications and can improve parameterization of individual-based bioenergetic models. Full article

(This article belongs to the Special Issue Studies on Age, Growth and Reproduction of Fishes)

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30 pages, 5342 KB

Open AccessEditor’s ChoiceArticle

Biological Stress Responses of Organisms to Microplastic Pollution in the Bulgarian Part of the Black Sea

by Albena Alexandrova, Nesho Chipev, Elina Tsvetanova, Madlena Andreeva, Svetlana Mihova, Selen Kyazim, Valentina Doncheva, Kremena Stefanova, Petya Ivanova, Elitsa Stefanova, Violin Raykov, Dimitar Dimitrov and Yordan Raev

Fishes 2026, 11(6), 312; https://doi.org/10.3390/fishes11060312 - 23 May 2026

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Abstract

Plastic pollution has emerged as one of the most pervasive environmental challenges, with microplastics (MPs) widely distributed across marine ecosystems worldwide. This study aimed to assess the uptake of MPs by key fish and invertebrate species from different locations in the coastal zone [...] Read more.

Plastic pollution has emerged as one of the most pervasive environmental challenges, with microplastics (MPs) widely distributed across marine ecosystems worldwide. This study aimed to assess the uptake of MPs by key fish and invertebrate species from different locations in the coastal zone of the Bulgarian Black Sea. Fish were collected during routine monitoring surveys in September–November 2024, while invertebrates were obtained via scuba diving. The presence of MPs in fish stomachs and invertebrate soft tissues, and their polymer composition, shape and size were analyzed using an Agilent 8700 LDIR Chemical Imaging System. Potential biological effects of ingested MPs were evaluated by an integrated Specific Oxidative Stress (SOS) index. The results revealed MP uptake levels comparable to those reported globally. Small-sized particles (<50 µm) with rounded shapes were most abundant across studied taxa. Polymer composition varied considerably depending on species and sampling region, indicating differences in exposure sources and environmental conditions. Oxidative stress levels in both fish and invertebrates showed substantial interspecific variation, and clear differences between the northern and southern region of the Bulgarian Black Sea. Overall, elevated uptake of MPs appears to contribute to oxidative stress in marine organisms, potentially affecting their health status, resilience, and adaptive capacity, as reflected by increased SOS index values. Full article

(This article belongs to the Special Issue Stress Ecology of Aquatic Animals)

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28 pages, 10868 KB

Open AccessEditor’s ChoiceArticle

Habitat Use, Residency, and Connectivity of Bull Sharks (Carcharhinus leucas) in the Bazaruto Seascape, Mozambique

by Stephanie K. Venables, Lukas Müller, Christoph A. Rohner, Andrea D. Marshall, Jimmy van Rijn, Nilza de Catarina, John D. Filmalter and Ryan Daly

Fishes 2026, 11(5), 291; https://doi.org/10.3390/fishes11050291 - 14 May 2026

Cited by 1 | Viewed by 2114

Abstract

Bull sharks (Carcharhinus leucas) are highly mobile coastal predators, whose broad movements complicate conservation planning, particularly in the Western Indian Ocean, where key habitats remain poorly understood. Using passive acoustic telemetry, this study assessed the habitat use, residency, and regional connectivity [...] Read more.

Bull sharks (Carcharhinus leucas) are highly mobile coastal predators, whose broad movements complicate conservation planning, particularly in the Western Indian Ocean, where key habitats remain poorly understood. Using passive acoustic telemetry, this study assessed the habitat use, residency, and regional connectivity of adult bull sharks within the Bazaruto Seascape, Mozambique, evaluating the area’s ecological role within a wider movement network. Sharks tagged around Bazaruto exhibited high residency (overall R_max = 0.45) and year-round presence, with core habitat concentrated along seaward reef systems and inshore areas off the San Sebastian Peninsula. Although most core habitat areas (82%) overlapped with existing marine protected areas, important habitats extended beyond protected area boundaries. In addition to supporting resident individuals, the seascape functioned as a seasonal waypoint within a regional movement corridor, with transient sharks exhibiting short periods (<5 days) of seasonal residency (primarily between May and November). Movement patterns revealed strong connectivity with other aggregation sites along the southeast African coast and occasional long-distance movements across the Mozambique Channel to Madagascar and beyond. These findings demonstrate that the Bazaruto Seascape provides both critical habitat and acts as a connectivity node for resident and transient bull sharks, highlighting the need for conservation strategies that combine local spatial protection with broader regional and transboundary management frameworks. Full article

(This article belongs to the Special Issue Habitat as a Template for Life Histories of Fish)

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20 pages, 2315 KB

Open AccessEditor’s ChoiceArticle

Age and Growth of Pacific Sardine (Sardinops sagax) off the U.S. Pacific Coast, 2012–2021

by Kelsey C. James, Jonathan M. Walker, Brittany D. Schwartzkopf, Emmanis Dorval and Brad E. Erisman

Fishes 2026, 11(5), 290; https://doi.org/10.3390/fishes11050290 - 14 May 2026

Viewed by 1053

Abstract

Pacific sardine (Sardinops sagax) are an economically important forage fish in the Northeast Pacific Ocean that undergo large changes in abundance over decadal scales and exhibit high individual variation in somatic growth. Past studies have suggested that somatic growth in Pacific [...] Read more.

Pacific sardine (Sardinops sagax) are an economically important forage fish in the Northeast Pacific Ocean that undergo large changes in abundance over decadal scales and exhibit high individual variation in somatic growth. Past studies have suggested that somatic growth in Pacific sardine may be density-dependent and vary regionally in response to environmental conditions. We analyzed somatic growth in Pacific sardine off the U.S. Pacific Coast during the recent period of low abundance (2012–2021) and compared the results to those of previous studies to evaluate evidence of spatial or temporal variation in growth. Sampled fish (n = 3228) ranged in length from 30 to 291 mm SL and in age from 0 to 9 years and displayed high individual variation in length-at-age and age-at-length. Length-at-age data were best explained by the von Bertalanffy growth model, and sample distribution simulations showed the dataset to be robust and unbiased. Estimated growth parameters (L_∞ = 243, K = 0.795, t₀ = −0.638) were consistent with an opportunistic life history strategy characterized by rapid growth, early maturation, and a short lifespan. While the estimated growth rate (K) was higher than in a previous study conducted during a period of high abundance and indicated that growth may be density-dependent, the parameter estimates from the previous study were influenced by sample distribution bias. Similarly, differences in study region, season, collection method, aging methods, and other factors precluded any definitive conclusions on the source of reported differences in growth patterns among studies. Full article

(This article belongs to the Special Issue Ecology of Fish: Age, Growth, Reproduction and Feeding Habits)

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23 pages, 3387 KB

Open AccessEditor’s ChoiceArticle

Revealing Ontogenetic Vertical Migration in Deep-Sea Grenadiers (Macrouridae) from the Southwestern Atlantic Through Otolith Microchemistry

by César Santificetur, Rodolfo Miguel Silva, Ana Méndez, Jorge Pisonero and Alberto Teodorico Correia

Fishes 2026, 11(5), 288; https://doi.org/10.3390/fishes11050288 - 12 May 2026

Viewed by 893

Abstract

Understanding the life-history strategies of deep-sea fishes is essential for improving ecological knowledge and informing conservation efforts. Using otolith microchemistry, this study reconstructed the ontogenetic movement patterns of four grenadier species (Nezumia aequalis, Hymenocephalus billsam, Coelorinchus marinii, and Malacocephalus [...] Read more.

Understanding the life-history strategies of deep-sea fishes is essential for improving ecological knowledge and informing conservation efforts. Using otolith microchemistry, this study reconstructed the ontogenetic movement patterns of four grenadier species (Nezumia aequalis, Hymenocephalus billsam, Coelorinchus marinii, and Malacocephalus occidentalis) caught in the continental slope off southern Brazil (Southwestern Atlantic). Elemental signatures (Ba:Ca, Sr:Ca, Li:Ca, Mg:Ca, Mn:Ca, Ni:Ca, Cu:Ca, and Zn:Ca) were quantified along core-to-edge transects of sagittal otoliths using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Ontogenetic shifts were identified using change-point detection (PELT). A general decline in elemental incorporation with age was observed across species, consistent with ontogenetic physiological regulation. Species-specific multi-elemental patterns suggest distinct ecological strategies. Nezumia aequalis exhibited an abrupt decline in Ba:Ca, indicating an early-life environmental shift. Hymenocephalus billsam showed increasing Ba:Ca and Sr:Ca profiles, consistent with continued use of pelagic-associated water masses. Coelorinchus marinii and Malacocephalus occidentalis displayed more complex patterns, with the latter showing pronounced Ba:Ca and Zn:Ca peaks that may reflect mid-life habitat shifts or physiological events. Mn:Ca ratios differed between pelagic and demersal species. Otolith microchemistry combined with change-point analysis could provide insights into deep-sea fish ontogeny, although interpretations should consider both environmental and physiological influences. Full article

(This article belongs to the Special Issue Application of Otoliths in Fish Ecology and Fisheries)

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13 pages, 2268 KB

Open AccessEditor’s ChoiceArticle

Dietary Lysophospholipids Enhance the Function of Lutein Rather than Lycopene in Pacific White Shrimp

by Chaojie Zhu, Ziling Song, Zhengwei Ye, Yanjiao Zhang, Jiahao Liu, Lindong Xiao, Chenchen Bian, Qiang Ma, Yuliang Wei, Mengqing Liang and Houguo Xu

Fishes 2026, 11(5), 285; https://doi.org/10.3390/fishes11050285 - 11 May 2026

Cited by 1 | Viewed by 810

Abstract

Our previous studies found that lipid emulsifiers can promote the absorption and deposition of liposoluble pigments in shrimp. The present study aimed to further investigate the effects of liposoluble pigments lutein (LUT) and lycopene (LYC), and their combination with lysophospholipids (LPL), on the [...] Read more.

Our previous studies found that lipid emulsifiers can promote the absorption and deposition of liposoluble pigments in shrimp. The present study aimed to further investigate the effects of liposoluble pigments lutein (LUT) and lycopene (LYC), and their combination with lysophospholipids (LPL), on the growth performance, body coloration, and lipid composition of Pacific white shrimp Penaeusvannamei. Five diets were formulated: a control diet (Control), Control + 0.02% lutein (LUT), Control + 0.02% lycopene (LYC), LUT + 0.1% LPL (LUT + LPL), and LYC + 0.1% LPL (LYC + LPL). The feeding trial lasted for 8 weeks. There were no significant differences in shrimp growth and body composition among all groups. Both LUT and LYC increased the redness (a*) and yellowness (b*) of cooked shrimp. LPL synergistically enhanced the pigmentation-improving effects of LUT but weakened those of LYC. Additionally, LYC decreased the redness and yellowness of raw shrimp. Both LUT and LYC reduced the contents of saturated fatty acids and EPA while increasing the DHA content; LPL further enhanced this modulatory effect. In conclusion, LPL acts synergistically with LUT to improve the body coloration and modify the fatty acid composition of Pacific white shrimp, but its effect with LYC is limited. Full article

(This article belongs to the Special Issue Effect of Dietary Supplementation on the Growth and Immunity of Fish and Shellfish—3rd Edition)

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23 pages, 1878 KB

Open AccessEditor’s ChoiceArticle

Impact of Solubilized Mannan Oligosaccharide Supplementation on Growth Performance, Digestive Health, Stress Resistance, and Economic Efficiency in Pacific White Shrimp (Penaeus vannamei) Raised in an Intensive Synbiotic System

by Danielle Alves da Silva, Flávia Abreu Everton, Gisely Karla de Almeida Costa, Suzianny Maria Bezerra Cabral da Silva, Fernando Leandro dos Santos, Rodrigo Antônio Ponce de Leon Ferreira de Carvalho, Giovani Sampaio Gonçalves, João Fernando Albers Koch and Luis Otavio Brito

Fishes 2026, 11(5), 279; https://doi.org/10.3390/fishes11050279 - 9 May 2026

Cited by 2 | Viewed by 1119

Abstract

The present study investigated how dietary inclusion of solubilized mannan oligosaccharide (MOS) influences growth performance, digestive health, stress resilience, and production profitability in Pacific white shrimp (Penaeus vannamei) reared under intensive synbiotic conditions. Juveniles averaging 3.00 ± 0.04 g were stocked [...] Read more.

The present study investigated how dietary inclusion of solubilized mannan oligosaccharide (MOS) influences growth performance, digestive health, stress resilience, and production profitability in Pacific white shrimp (Penaeus vannamei) reared under intensive synbiotic conditions. Juveniles averaging 3.00 ± 0.04 g were stocked at 100 shrimp m⁻² and fed experimental diets containing 0 (control), 1.0, 2.0, or 4.0 g kg⁻¹ MOS for 60 days. Shrimp receiving 1.0 g kg⁻¹ MOS showed higher growth rate, improved feed conversion, and greater final body weight than the control (p < 0.05), indicating enhanced feed utilization efficiency and better overall performance. Gut morphology improved in MOS-fed treatments, with increased mucosal fold height and enterocyte height, suggesting increased nutrient absorption and improved gut functionality. Gut presumptive total count remained relatively stable among treatments, although Bacillus counts tended to increase with solubilized MOS supplementation. Under ammonia and nitrite stress, supplemented groups showed higher survival and reduced gill damage, indicating improved physiological tolerance and health status. Economic analysis demonstrated that 1.0 and 2.0 g kg⁻¹ MOS achieved the best cost–benefit ratios under intensive conditions. Overall, moderate MOS supplementation enhanced growth, gut morphology, stress resistance, and economic efficiency. Polynomial regression analysis, based on the four dietary inclusion levels evaluated, suggested that approximately 1.5 g kg⁻¹ MOS may represent an estimated optimal inclusion level. Full article

(This article belongs to the Special Issue Sustainable Aquaculture of Crustaceans)

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16 pages, 1434 KB

Open AccessEditor’s ChoiceArticle

Anthropogenic Particle Ingestion in Atlantic Chub Mackerel (Scomber colias Gmelin, 1789) from the Saronikos Gulf: Occurrence, Characteristics, and Biological Associations

by Niki Milatou, Odysseas Papadopoulos-Michalas and Persefoni Megalofonou

Fishes 2026, 11(5), 272; https://doi.org/10.3390/fishes11050272 - 4 May 2026

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Abstract

Marine anthropogenic particle pollution is a major environmental concern due to its persistence and widespread distribution. Microplastics are widely recognized as a subset of anthropogenic particles originating from synthetic polymers. This study examines the occurrence, characteristics, and biological associations of anthropogenic particles ingested [...] Read more.

Marine anthropogenic particle pollution is a major environmental concern due to its persistence and widespread distribution. Microplastics are widely recognized as a subset of anthropogenic particles originating from synthetic polymers. This study examines the occurrence, characteristics, and biological associations of anthropogenic particles ingested by Atlantic chub mackerel from the Saronikos Gulf. A total of 179 specimens were analyzed for anthropogenic particles in the gastrointestinal tract, while muscle tissue was examined in 51 individuals. Anthropogenic particles were detected in the gastrointestinal tract of 74% of individuals and were also present in muscle tissue in 41% of the analyzed specimens. Fibers were the dominant particle type, representing approximately 60% of the identified particles, followed by fragments at 40%. The majority of particles were micro-sized (<5 mm), although meso- and macro-sized particles were also recorded. Black-colored particles predominated, accounting for approximately 53% of the total. No significant differences in anthropogenic particle abundance were observed between sexes, and no consistent seasonal patterns were detected, except for higher occurrence in early autumn compared to winter, although this result should be interpreted with caution due to uneven sample sizes among sampling periods. No statistically significant correlations were found between anthropogenic particle abundance in the gastrointestinal tract or muscle tissue and fish size, condition factor, or stomach fullness. Overall, the findings highlight this species as a suitable bioindicator for monitoring anthropogenic particle pollution and provide baseline information for future assessments in the Saronikos Gulf. Particle identification was based on visual characterization without spectroscopic confirmation; therefore, the detected particles are considered anthropogenic and their polymer composition could not be definitively confirmed. Full article

(This article belongs to the Special Issue Plastics in Fish and Shellfish)

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19 pages, 1867 KB

Open AccessEditor’s ChoiceArticle

Effects of Dietary Arachidonic Acid Concentration on Growth, Fatty Acid Profile, and Inflammatory/Redox Status of Juvenile Clam Sinonovacula constricta

by Yuxiang Zhu, Yueyue Fu, Kai Liao, Yang Liu, Yang Zhang and Jilin Xu

Fishes 2026, 11(5), 262; https://doi.org/10.3390/fishes11050262 - 27 Apr 2026

Viewed by 695

Abstract

Dietary arachidonic acid (ARA) is essential for aquatic animal growth and health, but studies in bivalves are still limited. Here, microcapsule diets with increasing ARA concentrations (ARA1-6 groups: 0.35, 3.01, 5.25, 6.88, 8.69, and 10.27 mg g⁻¹ dry matter) were prepared by [...] Read more.

Dietary arachidonic acid (ARA) is essential for aquatic animal growth and health, but studies in bivalves are still limited. Here, microcapsule diets with increasing ARA concentrations (ARA1-6 groups: 0.35, 3.01, 5.25, 6.88, 8.69, and 10.27 mg g⁻¹ dry matter) were prepared by spray drying, and clam Sinonovacula constricta juveniles were fed these diets for 14 days. Results showed that dietary ARA concentrations did not significantly affect clams’ survival, weight gain, and shell length gain rates. The clams in the ARA6 group had significantly higher crude lipid content than those in the other microcapsule groups. The ARA concentrations in the clams increased with higher dietary ARA, while n-3 polyunsaturated fatty acids (PUFAs) and eicosapentaenoic acid (EPA) concentrations decreased. The mRNA levels of cyclooxygenase 2 and 5-lipoxygenase type 2 were significantly higher in the ARA5 and ARA6 groups compared to the ARA1 group. The mRNA levels of 5-lipoxygenase type 3, toll-like receptor 4, and nuclear factor-kappa b p50 (nfκb p50) were significantly higher in the ARA6 group compared to the ARA1 group. As dietary ARA concentrations increased, the mRNA levels of glutamate–cysteine ligase catalytic subunit and glutathione S-transferase, along with malondialdehyde (MDA) content, increased in the clams. Additionally, the superoxide dismutase and catalase activities in the ARA5 and ARA6 groups were significantly higher than those in the ARA1 and ARA2 groups. Clam ARA content, acting as a central node, showed very strong positive correlations with MDA and cyclooxygenase 2, and very strong negative correlations with EPA and the n-3/n-6 PUFA ratio. Our results revealed that high dietary ARA, while not affecting growth, reduced the n-3/n-6 PUFA ratio and induced a response characterized by the upregulation of NF-κB and Nrf2 pathway genes in S. constricta. Full article

(This article belongs to the Section Aquatic Invertebrates)

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23 pages, 2513 KB

Open AccessEditor’s ChoiceArticle

Reviving Oyster Aquaculture in Romania: A Scientifically Driven Study Aiming at Obtaining Missing-Link Data for Successful Production

by Victor Niță, Leonardo Aguiari, Carmen Georgeta Nicolae, Daniela Roșioru, Aurelia Ţoţoiu and Magda Nenciu

Fishes 2026, 11(5), 255; https://doi.org/10.3390/fishes11050255 - 22 Apr 2026

Viewed by 1940

Abstract

Oyster aquaculture offers promising opportunities for diversifying marine production in the Romanian Black Sea, where favorable environmental conditions and recent regulatory developments support shellfish farming. This study aimed to generate baseline data for the cultivation of the Pacific oyster, Magallana gigas, through [...] Read more.

Oyster aquaculture offers promising opportunities for diversifying marine production in the Romanian Black Sea, where favorable environmental conditions and recent regulatory developments support shellfish farming. This study aimed to generate baseline data for the cultivation of the Pacific oyster, Magallana gigas, through an in situ experimental trial conducted off Mamaia Bay, Romania. A 50 m experimental long-line system was deployed at 13.5 m depth, and triploid oysters were cultured for one year at two depth horizons (3 m and 6 m). The growth performance, meat yield, Condition Index, microbiological quality, environmental parameters, and epibiotic communities were monitored monthly. Cultivation depth significantly influenced oyster growth, with individuals reared at 6 m consistently achieving a greater wet weight and shell length than those at 3 m. Growth rates peaked during spring, and meat yield values indicated good commercial quality. Environmental monitoring showed strong seasonal variability, with high summer temperatures and reduced dissolved oxygen associated with increased mortality. Microbiological analyses revealed higher bacterial loads during warm months. The Condition Index classified the oysters as generally “fine” to occasionally “special”. Overall, the results demonstrate that Black Sea conditions can support successful cultivation of M. gigas, although seasonal environmental stress and epibiosis require appropriate farm management. Full article

(This article belongs to the Special Issue Innovations and Sustainability in Aquaculture Production and Processing)

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21 pages, 2346 KB

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Genetic Analysis of Mixed Individuals Reveals Different Spawning Populations of the Tetrapturus pfluegeri (Longbill Spearfish) in the Western Atlantic Ocean

by Suhaila Karim Khalil Jaser, Caio Augusto Perazza, Rodrigo Rodrigues Domingues, Freddy Arocha, Eric Hallerman and Alexandre Wagner Silva Hilsdorf

Fishes 2026, 11(4), 253; https://doi.org/10.3390/fishes11040253 - 21 Apr 2026

Viewed by 975

Abstract

Populations of several billfish species are declining due to overfishing and bycatch, and fundamental aspects of their biology and population dynamics remain poorly understood. We provide the first assessment of the population genetic structure of longbill spearfish (Tetrapturus pfluegeri) in the [...] Read more.

Populations of several billfish species are declining due to overfishing and bycatch, and fundamental aspects of their biology and population dynamics remain poorly understood. We provide the first assessment of the population genetic structure of longbill spearfish (Tetrapturus pfluegeri) in the western Atlantic Ocean. We screened variation at 12 nuclear microsatellite loci (n = 144) and mitochondrial DNA control region sequences (mtCR, n = 177). Both marker types revealed three genetically differentiated clusters, with mean values for microsatellites showing differentiation of F_ST = 0.136 and D_EST = 0.201, and for mtCR F_ST = 0.645. Microsatellite markers demonstrated moderate-to-high genetic diversity, with a mean allelic richness of 6.73 alleles per locus, moderate heterozygosities (Ho = 0.446, He = 0.604), and a positive inbreeding coefficient (F_IS = 0.22) across the three sample collection sites. The overall estimated effective population size was 789.2 (95% CI: 246.7–∞). The mtCR exhibited 96 haplotypes, with high haplotype (0.989 ± 0.003) and nucleotide (0.025 ± 1.3%) diversities. We found higher mean relatedness within clusters than among them, supporting the interpretation of population subdivision and the Wahlund effect. Tajima’s D and Fu’s Fs were negative across all localities, with significant values observed along the Brazilian coast but not in the Caribbean Sea. These neutrality test results, together with low Harpending’s raggedness indices from DNA sequence mismatch distributions, are consistent with historical demographic expansion. Our findings establish a genetic baseline for fishery monitoring and management, contributing to the conservation of T. pfluegeri populations in the western Atlantic Ocean. Full article

(This article belongs to the Special Issue Conservation and Population Genetics of Fishes)

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14 pages, 995 KB

Open AccessEditor’s ChoiceArticle

Earthen Pond Grow-Out of Chinese Mitten Crab Eriocheir sinensis: All-Female Culture Is Superior to Mixed-Sex and All-Male Alternatives

by Guangbao Zhang, Abdulai Merry Kamara, Zhijie Zhou, Wenbin Chen, Yang Jie, Chaoshu Zeng, Wenquan Zhou and Xugan Wu

Fishes 2026, 11(4), 248; https://doi.org/10.3390/fishes11040248 - 18 Apr 2026

Cited by 1 | Viewed by 899

Abstract

Monosex culture has been shown to enhance farming productivity in several decapod crustaceans, and it has also been suggested that this approach holds high potential for the sustainable aquaculture of the Chinese mitten crab, Eriocheir sinensis. Pronounced sexual dimorphism in E. sinensis [...] Read more.

Monosex culture has been shown to enhance farming productivity in several decapod crustaceans, and it has also been suggested that this approach holds high potential for the sustainable aquaculture of the Chinese mitten crab, Eriocheir sinensis. Pronounced sexual dimorphism in E. sinensis facilitates the implementation of a monosex culture. This study aimed to compare the growth, gonadal development, culture performance, and economic outcomes of two monosex culture modes, i.e., an all-female culture and an all-male culture, as well as a mixed-sex culture (males: females = 1:1) during an 8-month growth period in earthen ponds. The results showed that: (1) Throughout the grow-out period, the average body weight in both monosex culture treatments was consistently higher than in the mixed-sex treatment, with a significantly greater body weight in the all-female and all-male treatments than that of males and females in the mixed-sex treatment being detected during mid-June and October, respectively (p < 0.05). (2) The percentages of both sexes that had finished puberty molting were mostly similar between the monosex and mixed-sex treatments between July 20th to October 10th, although the all-female treatment had a significantly lower puberty molting percentage than the mixed-sex treatment on August 10th (p < 0.05). Gonadosomatic index (GSI) values were similar between the monosex and mixed-sex treatments for both males and females (p > 0.05). (3) At harvest period, the final body weight in the all-male treatment was significantly higher than that of the mixed-sex treatment (p < 0.05). In contrast, the all-female treatment exhibited a significantly higher survival rate and a lower limb injury rate compared with the mixed-sex treatment (p < 0.05). As a result, the yield of the all-male and all-female treatments exceeded that of the males and females in the mixed-sex treatment by 24% and 13%, respectively. Additionally, the mixed-sex treatment also had a significantly higher feed conversion ratio (p < 0.05). Finally, the monosex treatments had a higher proportion of large crabs (males ≥ 200 g, females ≥ 175 g) and a lower proportion of small crabs (males ≤ 150 g, females ≤ 100 g) compared to the mixed-sex treatment. (4) In terms of economic benefits, net profit and return on investment (ROI) were highest under the all-female treatment, while the mixed-sex treatment recorded the lowest total return, net profit, and ROI (p < 0.05). In conclusion, an all-female culture is recommended for the grow-out culture period of E. sinensis, as it led to a higher survival rate, produced larger-sized crabs and generated greater overall economic benefit. Full article

(This article belongs to the Section Sustainable Aquaculture)

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13 pages, 2853 KB

Open AccessEditor’s ChoiceArticle

The Potential Drug Target (Glycolysis Pathway) of the Spore Stage of the Pathogen Enterocytozoon hepatopenaei in Shrimp Farming

by Bo Zhu, Juan Feng, Dong Qian, Ping Zhuang, Changkao Mu, Jiong Chen and Rongrong Ma

Fishes 2026, 11(4), 229; https://doi.org/10.3390/fishes11040229 - 15 Apr 2026

Viewed by 896

Abstract

Enterocytozoon hepatopenaei (EHP) is a specialized parasitic microsporidian that causes significant economic losses to the shrimp farming industry. The glycolysis pathway plays an important role in the survival of EHP spores in vitro. In this study, key enzyme genes involved in the glycolysis [...] Read more.

Enterocytozoon hepatopenaei (EHP) is a specialized parasitic microsporidian that causes significant economic losses to the shrimp farming industry. The glycolysis pathway plays an important role in the survival of EHP spores in vitro. In this study, key enzyme genes involved in the glycolysis pathway of EHP were analyzed, and purified spores were treated with KOH and a low temperature (−20 °C) to promote or inhibit germination. Quantitative analysis and enzyme activity of the initiating key gene hexokinase (HK) and the core link gene glyceraldehyde 3-phosphate dehydrogenase (GAPDH) were conducted to explore the energy response characteristics of germinating spores. The results showed that HK and GAPDH genes had significant differences from the host, based on phylogenetic analysis. The expression of HK gene and enzyme activity increased after promoting germination treatment. The expression of the GAPDH gene was stable, but the activity of the GAPDH enzyme increased significantly after germination promotion. These findings indicate that the inhibition of the HK gene expression level and GAPDH protein level can block spore germination and invasion in vitro, which could be used as potential control targets for EHP. Full article

(This article belongs to the Special Issue Advances in the Immunology of Aquatic Animals)

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20 pages, 4950 KB

Open AccessEditor’s ChoiceArticle

Brown Trout (Salmo trutta) Abundance and Biomass in Mediterranean Rivers: Environmental, Genetic, and Management Drivers

by Rafel Rocaspana, Carles Alcaraz and Enric Aparicio

Fishes 2026, 11(4), 217; https://doi.org/10.3390/fishes11040217 - 2 Apr 2026

Viewed by 1348

Abstract

Brown trout (Salmo trutta) populations at the southern edge of the species’ distribution are increasingly exposed to interacting climatic, biotic, genetic, and anthropogenic pressures. This study provides an integrative assessment of the drivers of variation in brown trout density, biomass, and [...] Read more.

Brown trout (Salmo trutta) populations at the southern edge of the species’ distribution are increasingly exposed to interacting climatic, biotic, genetic, and anthropogenic pressures. This study provides an integrative assessment of the drivers of variation in brown trout density, biomass, and size structure across six Mediterranean river basins in Catalonia (NE Iberian Peninsula), based on long-term standardized electrofishing surveys (2016–2025; 88 sites). Generalized linear mixed models revealed that mean summer temperature, genetic introgression from hatchery-derived Atlantic lineages, and the density of introduced fish species were the most consistent negative predictors of total density, biomass, and juvenile abundance (<120 mm FL). Hydrological and nutrient variables showed comparatively weak or non-significant effects relative to thermal and biotic predictors. Fishing regulations significantly influenced the biomass and density of larger trout (>220 mm FL), with lower values in harvest-allowed sections, whereas total density was less responsive to regulation. These findings indicate that Mediterranean brown trout populations are primarily constrained by thermal conditions, genetic integrity, and biological invasions, with implications for conservation and fishery management under ongoing climate warming. Full article

(This article belongs to the Special Issue Sustainable Fisheries Dynamics)

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19 pages, 312 KB

Open AccessEditor’s ChoiceArticle

Partial Fishmeal Replacement with Defatted Hermetia illucens Meal in Offshore-Farmed Gilthead Seabream (Sparus aurata): Effects on Fillet Quality and Microbiological Stability

by Marianna Oteri, Ambra Rita Di Rosa, Vittorio Lo Presti, Giovanni Toscano, Filippo Giarratana and Biagina Chiofalo

Fishes 2026, 11(4), 211; https://doi.org/10.3390/fishes11040211 - 1 Apr 2026

Cited by 2 | Viewed by 1193

Abstract

The search for sustainable alternatives to fishmeal (FM) in aquafeeds represents a major challenge for modern aquaculture. This study evaluated the effects of replacing 35% of FM with defatted Hermetia illucens larvae meal (HIM35) in diets of gilthead seabream (Sparus aurata) [...] Read more.

The search for sustainable alternatives to fishmeal (FM) in aquafeeds represents a major challenge for modern aquaculture. This study evaluated the effects of replacing 35% of FM with defatted Hermetia illucens larvae meal (HIM35) in diets of gilthead seabream (Sparus aurata) reared under full-scale commercial offshore farming conditions. Fillet nutritional quality, fatty acid and amino acid profiles, mineral composition, and microbiological stability during refrigerated storage were assessed. Dietary HIM35 significantly modified the fatty acid profile, increasing saturated fatty acids, particularly lauric and myristic acids, and n-6 polyunsaturated fatty acids. Despite reductions in eicosapentaenoic and docosahexaenoic acids (EPA and DHA), total PUFA and lipid health indices remained within recommended ranges and EPA + DHA levels were above 8%, supporting both fillet nutritional value and fish physiological requirements. Enzymatic indices based on product-to-precursor fatty acid ratios suggested reduced Δ5 + Δ6-desaturase activity. The amino acid profile showed increases in selected essential and non-essential amino acids, while overall protein quality was preserved. HIM35 fillets showed lower sodium and higher zinc contents, whereas increased aluminum levels warrant further investigation. Microbiological analyses confirmed the absence of foodborne pathogens and no effects on spoilage dynamics. Overall, HIM35 represents a safe and effective partial replacement for FM supporting sustainable aquafeed strategies. Full article

(This article belongs to the Special Issue Towards Sustainable Aquafeeds: Strategies and Mechanisms of Fish Meal and Oil Replacement)

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15 pages, 1459 KB

Open AccessEditor’s ChoiceArticle

Effects of GnRHa Delivery Systems on Spermiation and Sperm Quality in Captive Male Thicklip Grey Mullet (Chelon labrosus)

by Lambros E. Kokokiris, George Minos, Cosmas Nathanailides, Maria Papadaki and Constantinos C. Mylonas

Fishes 2026, 11(4), 210; https://doi.org/10.3390/fishes11040210 - 1 Apr 2026

Viewed by 926

Abstract

The aim of this study was to evaluate the effects of a gonadotropin-releasing hormone analogue (GnRHa), administered through injections or with sustained-release implants, on spermiation and sperm quality in thicklip grey mullet, Chelon labrosus. Male broodstock transferred from extensive lagoons were randomly [...] Read more.

The aim of this study was to evaluate the effects of a gonadotropin-releasing hormone analogue (GnRHa), administered through injections or with sustained-release implants, on spermiation and sperm quality in thicklip grey mullet, Chelon labrosus. Male broodstock transferred from extensive lagoons were randomly allocated to three treatment groups: (a) weekly saline injections (Saline-INJ), (b) weekly GnRHa injections (10 μg kg⁻¹ bw; GnRHa-INJ), and (c) a single GnRHa EVAc implant (50 μg kg⁻¹ bw; GnRHa-IMP). Males were maintained with females under the same treatment protocols and allowed to spawn. Sperm condition, density, motility, duration of motility, and androgen levels were evaluated weekly at five sampling points (Days 0, 7, 14, 21, and 28). All males exhibited complete spermiation during the first two weeks (Days 0 and 7), followed by a gradual decline throughout the rest of the study (Days 14 and 21). This pattern of decline was not as evident in the groups treated with GnRHa, especially in the GnRHa-INJ group. Sperm density, motility, and motility duration varied strongly over time; however, no significant differences were observed among treatments. GnRHa treatment prolonged the spermiation period and delayed its seasonal decline without significantly altering sperm quality. These results may enable more frequent sperm collection and greater sperm availability, as inferred from the spermiation condition (SCI) and qualitative observations. Full article

(This article belongs to the Special Issue Reproductive Physiology of Fishes)

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32 pages, 1669 KB

Open AccessEditor’s ChoiceReview

Adaptation Mechanisms of Aquatic Animals to Saline–Alkaline Water Aquaculture: Physiological, Energetic and Molecular Perspectives

by Yingsha Qu, Huichen Li, Bo Zhang, Hongwu Cui, Jianlei Chen, Yong Xu, Zhengguo Cui, Keming Qu and Hao Li

Fishes 2026, 11(4), 202; https://doi.org/10.3390/fishes11040202 - 27 Mar 2026

Cited by 5 | Viewed by 2756

Abstract

Saline–alkaline water constitutes a vital strategic non-traditional fishery resource in China, characterized by high pH values, elevated carbonate alkalinity, and complex ionic compositions. These extreme environmental conditions impose significant stress on aquatic animals, mainly by inducing ionic toxicity and disrupting acid–base regulatory mechanisms. [...] Read more.

Saline–alkaline water constitutes a vital strategic non-traditional fishery resource in China, characterized by high pH values, elevated carbonate alkalinity, and complex ionic compositions. These extreme environmental conditions impose significant stress on aquatic animals, mainly by inducing ionic toxicity and disrupting acid–base regulatory mechanisms. Such disruptions subsequently lead to osmotic imbalance, metabolic dysregulation, and immunosuppression, thus restricting the survival and growth of aquatic species in aquaculture systems. Consequently, the sustainable development of the saline–alkaline aquaculture is imperative for enhancing production efficiency and promoting the utilization of marginal land and water resources. This review comprehensively summarizes the current status of saline–alkaline aquaculture and highlights the stress-inducing impacts of salinity, alkalinity, and specific ionic ratios on teleost fishes and crustaceans. It further explores key adaptive mechanisms, including osmoregulatory and ionoregulatory strategies, bioenergetic trade-offs related to oxygen consumption and ammonia excretion, coordinated antioxidant and innate immune responses, as well as recent findings from multi-omics research. This review aims to offer a scientific foundation for the selection and breeding of saline–alkaline-tolerant strains, the precise regulation of aquaculture water environments, and the development of ecological aquaculture models in saline–alkaline regions, thereby facilitating the sustainable utilization of saline–alkaline land and water resources. Full article

(This article belongs to the Special Issue Influences of Environmental Change on Fishes and Fisheries)

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44 pages, 1726 KB

Open AccessEditor’s ChoiceReview

Responses of Rainbow Trout to Fishmeal Replacement with Terrestrial/Aerial Animal Proteins

by Ewen McLean, Sofea Smith, Ford Brodeur and Frederic T. Barrows

Fishes 2026, 11(4), 198; https://doi.org/10.3390/fishes11040198 - 26 Mar 2026

Viewed by 2215

Abstract

Research designed to reduce or eliminate fishmeal (FM) in trout feeds, for reasons that have changed over time, has been conducted for over a century. Reducing the dependency on FM remains one of the most urgent issues facing the industry. Feed represents the [...] Read more.

Research designed to reduce or eliminate fishmeal (FM) in trout feeds, for reasons that have changed over time, has been conducted for over a century. Reducing the dependency on FM remains one of the most urgent issues facing the industry. Feed represents the most expensive operational cost of fed aquaculture, and is responsible for ecosystem disturbance following nutrient discharges. Rainbow trout, the second most farmed salmonid globally, can be raised completely without FM or fish oil (FO), with its growth and efficiency not differing from trout fed FM-based feeds. However, ingredient choice and nutrient supplementation strongly influence physiological responses, efficiency, and long-term outcomes. As land animal proteins are increasingly used in place of FM, both with and void of dietary FO, their distinct biological effects warrant focused evaluation. Although numerous studies have synthesized findings across various alternative protein categories including those with insect proteins and animal by-products, this literature is widely disseminated and sometimes difficult to access. The present contribution focuses on terrestrial/aerial animal proteins that have been used to totally replace FM in rainbow trout feeds. Attention is given to their effects on physiological control processes that may influence production efficiency. Areas worthy of future study are identified and include long-term performance and health dynamics, the refinement of nutritional and formulation strategies, and the broader evaluation of biological interactions and system-level outcomes. Full article

(This article belongs to the Special Issue Sustainable Aquaculture and Seafood Production)

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11 pages, 1603 KB

Open AccessEditor’s ChoiceArticle

First Mediterranean Records of Two African Crabs, the Mud Crab Panopeus africanus and the Pebble Crab Ilia spinosa (Crustacea, Decapoda, Brachyura)

by Alberto Gil-Fernández, Pere Abelló, Isabel Muñoz and Jose A. Cuesta

Fishes 2026, 11(3), 168; https://doi.org/10.3390/fishes11030168 - 14 Mar 2026

Cited by 1 | Viewed by 1305

Abstract

Two African crab species are recorded for the first time for the Mediterranean Sea. On the one hand, eight individuals of the mud crab Panopeus africanus were found in the port of Gandía, València, Spain. On the other hand, one zoea larva of [...] Read more.

Two African crab species are recorded for the first time for the Mediterranean Sea. On the one hand, eight individuals of the mud crab Panopeus africanus were found in the port of Gandía, València, Spain. On the other hand, one zoea larva of the pebble crab Ilia spinosa was identified in plankton samples collected in coastal waters adjacent to L’Albufera, València, Spain. These two Mediterranean findings represent the second records for these two African crab species outside their native Atlantic distributions. Identifications were confirmed using DNA barcoding. Comparisons with other African decapod species introduced into the Mediterranean are made to assess whether they may have followed similar transport patterns, which include two main pathways, natural larval expansion from nearby Atlantic populations or accidental transport mediated by ships’ ballast water or hull fouling. Full article

(This article belongs to the Special Issue Biology and Culture of Marine Invertebrates)

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23 pages, 3570 KB

Open AccessEditor’s ChoiceArticle

Habitat-Driven Population Parameters Insights for European Eel Anguilla anguilla (Linnaeus, 1758) in Croatian Waters

by Luka Glamuzina, Alexis Conides, Sanja Matić-Skoko, Matija Kresonja, Milorad Mrakovčić, Sanja Grđan, Matija Pofuk and Branko Glamuzina

Fishes 2026, 11(2), 125; https://doi.org/10.3390/fishes11020125 - 23 Feb 2026

Cited by 2 | Viewed by 1506

Abstract

Key parameters were estimated separately for the European eel, Anguilla anguilla (Linnaeus, 1758) subpopulations across freshwater and brackish environments within the Eastern Adriatic Eel Management Unit (EMU: EA). Between 2023 and 2024, European eel sampling was carried out at 23 locations along the [...] Read more.

Key parameters were estimated separately for the European eel, Anguilla anguilla (Linnaeus, 1758) subpopulations across freshwater and brackish environments within the Eastern Adriatic Eel Management Unit (EMU: EA). Between 2023 and 2024, European eel sampling was carried out at 23 locations along the Croatian coast (N = 678). Ages ranged from 1 to 13 years in freshwater and 1 to 8 years in brackish waters. The population structure was dominated by undifferentiated (42.8%) in freshwater and females (46.3%) in brackish habitats. Eels in freshwater exhibited a significantly higher b-coefficient in their length–weight relationship and better condition. Based on the otolith annuli patterns, age classes 3 to 5 predominated in both groups. A slightly longer asymptotic length and lower growth rate were found for the freshwater group compared to a shorter length and higher growth rate in the brackish habitat. Natural mortality was estimated at 0.174 ± 0.09 year⁻¹ and 0.191 ± 0.133 year⁻¹ for brackish and freshwater habitats, respectively. Total mortality was higher in freshwater (0.86 year⁻¹) in comparison with the brackish (0.83 year⁻¹) habitat. According to obtained results, more than 50% of eels aged three years are under exploitation. The maximum Yield per Recruit (Y/R) was 0.082 g/recruit in brackish at L_c = 44.88 cm, and a current L_c is 19.4 cm in the samples. In freshwater, Y/R peaked at 0.042 g/recruit at L_c = 55.49 and a current L_c 11.1 cm. It is recommended, following a precautionary approach to management, that the current fishing practices change in order to increase the minimum landing size (MLS), at least to 45 cm (above the current official MLS of 35 cm), to increase the fishing yield, and directly enhance population resilience. Findings emphasise the need for sustainable eel management policies considering different subpopulation parameters along the freshwater/brackish gradient at a small spatial scale when proposing and implementing stock management measures. Full article

(This article belongs to the Special Issue Life in Layers: Age and Growth of Fishes)

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19 pages, 2159 KB

Open AccessEditor’s ChoiceArticle

Phylogeographic Pattern and Genetic Structure of the Cyprinid Fish Microphysogobio kachekensis (Oshima 1926) in Mainland China and Hainan Island Based on Mitochondrial and Nuclear DNA

by Jin-Quan Yang, Jiabo Chen, Junjie Wang, Tian-Qi Zhou, Yuh-Wen Chiu, Hung-Du Lin and Wen-Sheng Ou

Fishes 2026, 11(2), 122; https://doi.org/10.3390/fishes11020122 - 19 Feb 2026

Cited by 1 | Viewed by 1721

Abstract

South China’s freshwater biodiversity has been shaped by Quaternary climatic oscillations and persistent geological barriers. We investigated the phylogeography and conservation implications of the primary freshwater fish Microphysogobio kachekensis across mainland China and Hainan Island using mitochondrial (cyt b and control region) and [...] Read more.

South China’s freshwater biodiversity has been shaped by Quaternary climatic oscillations and persistent geological barriers. We investigated the phylogeography and conservation implications of the primary freshwater fish Microphysogobio kachekensis across mainland China and Hainan Island using mitochondrial (cyt b and control region) and nuclear (RAG2 and rpS7-1) markers from 200 individuals. Mitochondrial analyses recovered two major lineages and multiple sublineages largely structured by drainage basins, whereas nuclear data resolved four geographically concordant lineages. Population differentiation was strong (high F_ST), and SAMOVA/AMOVA supported major barriers restricting gene flow, including the Qiongzhou Strait, Gulf of Tonkin, Yunkai Mountains, and Nanling Mountains. Ancestral-area reconstruction inferred the Pearl River region as the most likely source area, followed by dispersal to northern Hainan and subsequent expansion to southern Hainan and the Red River, with additional northward expansion to the Zhejiang–Fujian region. Despite high haplotype diversity, within-population nucleotide diversity was low, consistent with long-term river isolation and complex demographic history. We propose six ESUs and four MUs for evolutionarily informed conservation and to guide stock enhancement in southern China. Full article

(This article belongs to the Section Taxonomy, Evolution, and Biogeography)

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24 pages, 2260 KB

Open AccessEditor’s ChoiceReview

Utilization of Plant-Derived Essential Oils as Natural Alternatives for Controlling Fish Pathogens: A Critical Review of Their Use Against Aeromonas hydrophila

by Sasirekha Rajendran, Berta Maria Heinzmann, Juliana Cargnelutti and Bernardo Baldisserotto

Fishes 2026, 11(2), 120; https://doi.org/10.3390/fishes11020120 - 17 Feb 2026

Cited by 3 | Viewed by 2138

Abstract

Aeromonas hydrophila infection is typically linked to outbreaks of diseases and its pathogenicity seems to be connected to environmental stress in hosts whose immune systems are compromised. Fish diseases have long been treated using synthetic antibiotics, but there are environmental and health concerns [...] Read more.

Aeromonas hydrophila infection is typically linked to outbreaks of diseases and its pathogenicity seems to be connected to environmental stress in hosts whose immune systems are compromised. Fish diseases have long been treated using synthetic antibiotics, but there are environmental and health concerns regarding their use due to the development of bacterial resistance. It has been suggested that essential oils (EOs), which are alternative antibacterial agents, could be applied in the aquaculture industry. Their biodegradability, affordability, efficiency, and quick metabolism minimize the likelihood of them building up in bodily tissues and provoking bacterial resistance. EOs can directly influence bacteria, altering the lipid composition and structure of bacterial cell membranes, enhancing their permeability, and disrupting their structure. In addition, they can boost fish immunity and increase resistance to contagious bacteria. EOs can be incorporated into fish diets as nutritional additives and/or applied in baths. This review discusses the in vitro and in vivo methodologies used to study the effects of EOs on A. hydrophila and the results obtained so far, as well as perspectives for new studies. Full article

(This article belongs to the Special Issue Microbial Pathogens, Disease Control and Veterinary Drug Use in Aquaculture)

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21 pages, 1338 KB

Open AccessEditor’s ChoiceArticle

Phage-Based Approaches for Potential Integration into Bivalve Depuration Systems

by João Duarte, David Trindade, Carla Pereira, Ricardo Calado and Adelaide Almeida

Fishes 2026, 11(2), 103; https://doi.org/10.3390/fishes11020103 - 8 Feb 2026

Viewed by 1745

Abstract

The rising global demand for bivalves and declining water quality is placing increasing pressure on depuration facilities to ensure product safety and quality, leading to extended processing times and increased energy consumption. Bacteriophages (phages) offer a low-cost, environmentally friendly, and highly specific approach [...] Read more.

The rising global demand for bivalves and declining water quality is placing increasing pressure on depuration facilities to ensure product safety and quality, leading to extended processing times and increased energy consumption. Bacteriophages (phages) offer a low-cost, environmentally friendly, and highly specific approach that may enhance depuration efficiency. In this study, we evaluated a phage cocktail targeting Escherichia coli, Aeromonas hydrophila, Salmonella enterica serovar Typhimurium, and Vibrio parahaemolyticus to improve depuration at laboratory-scale using cockles (Cerastoderma edule). Three depuration experiments of 12 h were performed: (i) cockles artificially contaminated with E. coli or V. parahaemolyticus; (ii) cockles inoculated with all four bacteria; and (iii) naturally contaminated cockles. Phages reduced bacterial loads by 1.62 and 1.61 Log colony forming units per gram (CFU/g) for E. coli and V. parahaemolyticus, respectively. In experiments using the four bacterial strains, reductions of ~1.00 Log CFU/g were observed only at higher doses. This phage dose also caused bacterial reduction in naturally harvested animals by 1.00–1.28 Log CFU/g. Our findings suggest that, under phage selective pressure, bacteria may be released from bivalves, probably as result of phage-induced disruption of biofilms, destabilising bacterial colonisation. Therefore, bivalve exposure to phage doses prior to water disinfection can complement the depuration treatment, increasing decontamination efficiency and enhancing food safety. Full article

(This article belongs to the Section Processing and Comprehensive Utilization of Fishery Products)

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19 pages, 7319 KB

Open AccessEditor’s ChoiceArticle

Poropuntius in the Chao Phraya, Mae Klong, Salween, and Tenasserim River Basins in Southeast Asia with Description of a New Species from the Mae Klong Basin in Thailand (Cypriniformes, Cyprinidae) ^‡

by Lawrence M. Page, Zachary S. Randall, Weerapongse Tangjitjaroen, Hung Manh Phạm and Huy Duc Hoàng

Fishes 2026, 11(2), 102; https://doi.org/10.3390/fishes11020102 - 7 Feb 2026

Viewed by 1675

Abstract

A new species of Poropuntius endemic to the Mae Klong River basin is described and compared to nine congeneric species in the Mae Klong, Chao Phraya, Salween, and Tenasserim River basins. Species of Poropuntius in these basins are almost universally poorly known, with [...] Read more.

A new species of Poropuntius endemic to the Mae Klong River basin is described and compared to nine congeneric species in the Mae Klong, Chao Phraya, Salween, and Tenasserim River basins. Species of Poropuntius in these basins are almost universally poorly known, with information often confined to brief original descriptions. New morphological data are provided for most species, and differential comparisons are provided for all. Some species display a large amount of intraspecific variation, including ontogenetic variation related to environmental factors, and can be difficult to identify. Taxonomic revisionary studies are needed for wide-ranging species. Puntius faucis Smith, 1945, is not a species of Poropuntius, as currently assumed. Full article

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19 pages, 2922 KB

Open AccessEditor’s ChoiceArticle

IMTA Production of Pacific White Shrimp Integrated with Mullet, Sea Cucumber, Oyster, and Salicornia in a Biofloc System

by Enrique A. Estévez Hernández, Ivanilson Santos, Laura Moraes, Morena Salala Kashane, Marcelo H. Okamoto, Luís André Sampaio, Dariano Krummenauer, César S. B. Costa, Ricardo V. Rodrigues, Silvia Martínez-Llorens and Luís H. Poersch

Fishes 2026, 11(2), 98; https://doi.org/10.3390/fishes11020098 - 5 Feb 2026

Cited by 2 | Viewed by 1914

Abstract

Integrated multitrophic aquaculture (IMTA) emerges as a sustainable strategy to control the excess of solids and inorganic nutrients that tend to increase in the biofloc system (BFT) cycle, since the model integrates organisms from different trophic levels sharing the same system and nutrients. [...] Read more.

Integrated multitrophic aquaculture (IMTA) emerges as a sustainable strategy to control the excess of solids and inorganic nutrients that tend to increase in the biofloc system (BFT) cycle, since the model integrates organisms from different trophic levels sharing the same system and nutrients. Thus, this study compared a Penaeus vannamei monoculture system with an integrated biofloc system including Mugil liza, Holothuria grisea, Crassostrea tulipa, and Salicornia neei, focusing on water quality and the performance of organisms and systems. This study consisted of three monoculture systems (16 m³; 375 shrimp m⁻³) and three IMTA systems, composed of a shrimp tank (16 m³), a mullet tank (4 m³; 30 ind m⁻³), a combined tank (3 m³) for oysters (45 ind m⁻³) and sea cucumbers (3 ind m⁻²), and a Salicornia neei bed (2.78 m²; 37 ind m⁻²). All IMTA systems operated in recirculation without water exchange, using 10% of the established biofloc inoculum. The IMTA system had half the hydrated lime use (2.13 vs. 4.29 kg), lower solids (299.56 vs. 373.33 mg L⁻¹), and reduced sludge production (9.37 vs. 15.87 kg). Shrimp growth was similar in both systems. Mullet grew adequately with a survival rate of 95.8%, but oysters showed a survival rate of 45.7%. Sea cucumber had a survival rate of 100% until day 28, when a marked decline appeared, strongly correlated with rising temperature (>28 °C; r = −0.71). This resulted in a significant increase in solids in the last weeks, suggesting that the population decline reduces solids control capacity. Furthermore, the biofloc in IMTA was dominated by coccoid forms, with lower proportions of filamentous and cyanobacterial forms. Full article

(This article belongs to the Special Issue Integrated Multi-Trophic Aquaculture (IMTA))

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14 pages, 3937 KB

Open AccessEditor’s ChoiceArticle

Stability Assessment of a Submersible Net Cage with Vertical Buoyancy Columns Under Steady Currents

by Kengo Yaegashi, Kewen Wang, Shintaro Gomi and Tsutomu Takagi

Fishes 2026, 11(2), 92; https://doi.org/10.3390/fishes11020092 - 3 Feb 2026

Viewed by 1412

Abstract

Offshore aquaculture requires net cages that remain stable under strong currents and during submersion and emergence operations. In this study, we proposed a submersible net cage structure equipped with vertical buoyancy columns as an alternative to the conventional horizontal floating-frame cage and evaluated [...] Read more.

Offshore aquaculture requires net cages that remain stable under strong currents and during submersion and emergence operations. In this study, we proposed a submersible net cage structure equipped with vertical buoyancy columns as an alternative to the conventional horizontal floating-frame cage and evaluated its stability using a net geometry and load analysis system (NaLA system). Model-scale cages were tested in a recirculating flume tank at two current velocities, and the three-dimensional cage geometry was reconstructed using the multicamera through direct linear transformation method to validate the simulated cage inclination. The NaLA system accurately reproduced the measured geometry and time-varying inclination. After validation, stability was compared over a range of current velocities by tracking the cage inclination during the emergence phase. When mooring lines were attached to the top of the cage, the conventional floating-frame cage exhibited a smaller inclination than the buoyancy-column cage. However, relocating the mooring attachment point on the columns significantly improved the stability; attaching the moorings near the bottom of the columns generated the smallest final inclination and yielded a higher stability than the conventional cage. The buoyancy columns can outperform those of conventional designs when paired with an appropriate mooring configuration, thus offering a promising structure for applications under harsh offshore conditions. Full article

(This article belongs to the Section Fishery Facilities, Equipment, and Information Technology)

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15 pages, 1168 KB

Open AccessEditor’s ChoiceArticle

Disinfection Strategies for Euplotes spp. Control in Marine Copepod Cultures

by Maribeth Wichterman, Grace McCranie, Chase Taylor, Olivia Markham, Brittney Lacy, Matthew DiMaggio and Casey Murray

Fishes 2026, 11(2), 91; https://doi.org/10.3390/fishes11020091 - 2 Feb 2026

Viewed by 1622

Abstract

Marine copepods are an essential live feed for the culture of many marine ornamental fish and other finfish species, yet their production is frequently constrained by contamination from free-living ciliates. To address this challenge, the efficacy of three disinfectants (sodium hypochlorite, iodine, and [...] Read more.

Marine copepods are an essential live feed for the culture of many marine ornamental fish and other finfish species, yet their production is frequently constrained by contamination from free-living ciliates. To address this challenge, the efficacy of three disinfectants (sodium hypochlorite, iodine, and hydrogen peroxide) was evaluated for ciliate removal in cultures of two copepod species, Parvocalanus crassirostris and Oithona colcarva. Appropriate ranges of disinfectant concentrations and exposure durations were identified through a preliminary trial assessing the toxicity to Euplotes spp. over a 5-min period. Subsequent experiments tested three doses of each disinfectant to quantify ciliate removal success and egg hatch rates for each copepod species. Ciliate presence/absence showed no variation (100% in controls, 0% after disinfection), precluding statistical analysis except for one variable iodine trial, which was analyzed using Fisher’s Exact Test. Hatch and recovery rates were analyzed using binomial GLMMs with treatment as a fixed effect and replicate as a random effect, with Tukey-adjusted pairwise comparisons and α = 0.05. Sodium hypochlorite and hydrogen peroxide consistently removed all ciliates across tested concentrations, whereas iodine only achieved complete removal at the highest dose. The effects on hatch rate differed between species, with hydrogen peroxide producing the highest hatch rates in P. crassirostris (approximately 44 to 46% at 50–100 g/L for one minute) and sodium hypochlorite supporting the highest hatch in O. colcarva (up to 92% at 250 mg/L for one minute). These findings demonstrate that disinfectant performance is species-specific and that species-specific disinfection protocols are warranted to improve the reliability of copepod production in marine aquaculture. Full article

(This article belongs to the Special Issue Zooplankton Production Applied to Aquaculture)

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26 pages, 3001 KB

Open AccessEditor’s ChoiceArticle

Design, Construction, and Efficacy of a Novel Multiepitope Chimeric Vaccine Against Lumpfish (Cyclopterus lumpus) Infection

by Joy Chukwu-Osazuwa, Trung Cao, Ignacio Vasquez, Hajarooba Gnanagobal, Ahmed Hossain, Oluwatoyin Onireti, Setu Chakraborty, Vimbai Irene Machimbirike and Javier Santander

Fishes 2026, 11(2), 83; https://doi.org/10.3390/fishes11020083 - 30 Jan 2026

Viewed by 1326

Abstract

The development of effective vaccines is a critical step in effective disease management in aquaculture. This study introduces a novel Multiepitope Chimeric Vaccine (MCV) designed to enhance immunity in lumpfish against Vibrio anguillarum, Aeromonas salmonicida, Yersinia ruckeri, Moritella viscosa and [...] Read more.

The development of effective vaccines is a critical step in effective disease management in aquaculture. This study introduces a novel Multiepitope Chimeric Vaccine (MCV) designed to enhance immunity in lumpfish against Vibrio anguillarum, Aeromonas salmonicida, Yersinia ruckeri, Moritella viscosa and Piscirickettsia salmonis. Epitopes from major toxins and virulence factors were selected to construct the MCV in silico. Structural validation showed 96.7% of residues in favored regions, confirming stability. Codon optimization yielded a G+C content of 54.61% and a Codon Adaptation Index (CAI) of 1, indicating strong expression potential in Escherichia coli. Immune simulations predicted robust B- and T-cell responses, suggesting induction of both humoral and cell-mediated immunity. Experimental vaccination of lumpfish (n = 35/group) with E. coli-expressed MCV led to significantly elevated IgM levels at four- and six-weeks post-vaccination (p ≤ 0.05, p ≤ 0.01, respectively). Upon pathogen challenge, vaccinated groups showed delayed mortality against V. anguillarum, A. salmonicida, and P. salmonis, though survival differences were not statistically significant across treatments. These results highlight the immunogenicity potential of the MCV and its capacity to elicit targeted immune responses. However, further optimization is necessary to improve protective efficacy and survival outcomes. This study lays a foundation for the application of multiepitope vaccines in lumpfish aquaculture and supports ongoing efforts toward sustainable disease control strategies. Full article

(This article belongs to the Special Issue Aquatic Animal Diseases and Vaccine Development)

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19 pages, 657 KB

Open AccessEditor’s ChoiceArticle

The Copepod/Artemia Trade-Off in the Culture of Long Snouted Seahorse Hippocampus guttulatus

by Jorge Palma, Ismael Hachero-Cruzado, Miguel Correia and José Pedro Andrade

Fishes 2026, 11(2), 72; https://doi.org/10.3390/fishes11020072 - 23 Jan 2026

Viewed by 1893

Abstract

This study evaluated the effects of copepod use and copepod conditioning strategies on the growth and survival of long-snouted seahorse (Hippocampus guttulatus) juveniles from 1 to 60 days post-parturition (DPP). Four dietary treatments were tested: Artemia enriched for 24 h with [...] Read more.

This study evaluated the effects of copepod use and copepod conditioning strategies on the growth and survival of long-snouted seahorse (Hippocampus guttulatus) juveniles from 1 to 60 days post-parturition (DPP). Four dietary treatments were tested: Artemia enriched for 24 h with Isochrysis galbana (control), daily collected copepods, copepods unfed for 48 h, and copepods enriched for 24 h with I. galbana. Juveniles fed copepod-based diets exhibited significantly higher growth and survival (p < 0.05) than those fed enriched Artemia. Mean standard length increased from 1.3 ± 0.1 cm at release to 5.9 ± 0.2, 7.5 ± 1.4, 7.1 ± 1.2, and 7.3 ± 1.1 cm at 60 DPP for the enriched Artemia, daily collected copepods, unfed copepods, and enriched copepods treatments, respectively. Wet weight increased from 0.002 ± 0.001 g to 0.44 ± 0.07, 0.81 ± 0.40, 0.68 ± 0.30, and 0.76 ± 0.40 g, while final survival reached 20%, 60%, 33.3%, and 56%, respectively. Compared with enriched Artemia, copepod-based diets markedly enhanced juvenile performance, supporting faster growth and promoting favorable behavioral traits that contributed to improved survival. These results demonstrate that copepods constitute a superior live feed for early juvenile H. guttulatus; however, copepod conditioning strategies directly influence their nutritional quality and, consequently, seahorse growth and survival. The use of copepods throughout the first 60 DPP is therefore not only feasible but strongly recommended for optimizing juvenile H. guttulatus rearing performance. Full article

(This article belongs to the Special Issue Effects of Dietary Ingredients on Fish Nutrition and Health)

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30 pages, 1515 KB

Open AccessEditor’s ChoiceArticle

Genomic Diversity and Taxonomy of Aeromonas spp. in Aquarium Fish: Potential Role of Ornamental Fish as Hidden Carriers

by Muhammed Duman, Nihed Ajmi, Hector Carmona-Salido, Görkem Tasci, Artun Yıbar, Soner Altun, Jesús L. Romalde and Izzet Burcin Saticioglu

Fishes 2026, 11(2), 74; https://doi.org/10.3390/fishes11020074 - 23 Jan 2026

Viewed by 1448

Abstract

Aquarium fish are increasingly being recognized as reservoirs of zoonotic pathogens, with Aeromonas species posing a notable risk because of their environmental resilience and opportunistic pathogenicity. This study presents the most comprehensive genome-based investigation to date of Aeromonas diversity in aquarium fish, aiming [...] Read more.

Aquarium fish are increasingly being recognized as reservoirs of zoonotic pathogens, with Aeromonas species posing a notable risk because of their environmental resilience and opportunistic pathogenicity. This study presents the most comprehensive genome-based investigation to date of Aeromonas diversity in aquarium fish, aiming to characterize their taxonomic distribution, population structure, and genomic features. A total of 64 Aeromonas isolates were collected from various aquarium fish species. Wholegenome sequencing was conducted on all isolates to facilitate comparative genomic analyses. Key approaches included multilocus sequence typing (MLST), pairwise Digital DNA-DNA hybridization (dDDH), and the construction of a phylogenomic tree for species-level classification. Furthermore, a population structure analysis was performed to explore genomic diversity and evolutionary trends among the isolates. The results identified 14 distinct Aeromonas species, with A. veronii, A. caviae, and A. hydrophila being the most common. Importantly, several isolates exhibited taxonomic ambiguity, indicating the possible presence of new species or subspecies lineages. Furthermore, antimicrobial resistance gene profiles and virulence factor distributions varied significantly across clades, indicating genomic plasticity. This study highlights the underappreciated genomic complexity of Aeromonas populations in aquarium environments and raises concerns about the public health implications of pathogen reservoirs in ornamental fish. Full article

(This article belongs to the Special Issue Infection and Detection of Bacterial Pathogens in Aquaculture)

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14 pages, 297 KB

Open AccessEditor’s ChoiceArticle

Water Renewal Rate and Temperature on the Growth Performance and Physiology of Piaractus brachypomus in a Recirculating Aquaculture System (RAS)

by Pedro P. C. Pedras, Zandhor Lipovetsky, Fábio A. C. dos Santos, André de S. Souza, Luisa A. A. Silva, Gustavo S. da C. Júlio, Imaculada de M. C. Ananias, Sidney dos S. Silva, Ronald K. Luz and Gisele C. Favero

Fishes 2026, 11(1), 64; https://doi.org/10.3390/fishes11010064 - 19 Jan 2026

Viewed by 1373

Abstract

This study evaluated the effects of water renewal rate and temperature on the growth performance and physiological responses of juvenile Piaractus brachypomus reared in a recirculating aquaculture system (RAS). A total of 336 fish (1.35 ± 0.24 g) were distributed in six RAS [...] Read more.

This study evaluated the effects of water renewal rate and temperature on the growth performance and physiological responses of juvenile Piaractus brachypomus reared in a recirculating aquaculture system (RAS). A total of 336 fish (1.35 ± 0.24 g) were distributed in six RAS units under two water renewal rates (42 and 128 L h⁻¹) and three temperatures (26, 29, and 32 °C) for 45 days. Temperature was the main factor affecting growth, with higher final weight and total length at 29 and 32 °C throughout the experimental period. Water renewal rate significantly influenced feeding efficiency and energy allocation. Higher renewal (128 L h⁻¹) increased dissolved oxygen and daily feed intake and resulted in higher hemoglobin levels and hepatic lipid deposition, particularly at 32 °C, indicating greater metabolic activity. Conversely, the lower renewal rate (42 L h⁻¹) was associated with better feed conversion ratios at 29 °C and higher muscle lipid content at 26 °C, suggesting reduced energy expenditure. Hematocrit, total plasma protein, and cholesterol were primarily influenced by temperature, with higher values at 29 and 32 °C, while glucose, triglycerides, and liver enzymes were unaffected. Overall, temperatures of 29–32 °C optimized growth, while water renewal rate modulated feed utilization, physiological responses, and lipid deposition. These findings highlight the importance of jointly optimizing temperature and water renewal rate in RAS to enhance growth performance and metabolic balance in juvenile P. brachypomus. Full article

(This article belongs to the Special Issue Advances in the Physiology of Aquatic Organisms)

18 pages, 1938 KB

Open AccessEditor’s ChoiceArticle

Reproductive Dynamics of the Blonde Ray (Raja brachyura) in Portuguese Waters: Timing, Maturity and Fecundity

by Catarina Maia, Ivone Figueiredo, Bárbara Serra-Pereira, Neide Lagarto, Inês Farias and Teresa Moura

Fishes 2026, 11(1), 61; https://doi.org/10.3390/fishes11010061 - 17 Jan 2026

Viewed by 1176

Abstract

Within the Rajidae family, the blonde ray (Raja brachyura) is considered one of the less resilient species to fishing pressure and other anthropogenic pressures, primarily due to its late maturity and large maximum size, which can exceed 120 cm total length. [...] Read more.

Within the Rajidae family, the blonde ray (Raja brachyura) is considered one of the less resilient species to fishing pressure and other anthropogenic pressures, primarily due to its late maturity and large maximum size, which can exceed 120 cm total length. This is the first study to provide comprehensive insights into the reproductive biology of Raja brachyura in the continental waters of Portugal, with insights into its timing, maturity, and fecundity. It was determined that egg-laying occurs from February to November, with a peak observed between April and September. Males were reproductively active throughout the year, with highest proportions of active males observed between January and May. The length at first maturity was estimated at 95.2 cm for females and 90.0 cm for males, corresponding to 85% of the maximum observed length in each sex. The potential fecundity was estimated at 115 follicles per female per year, and evidence suggests that the species has a determinate fecundity. The findings reinforce the appropriateness of current management measures in Portuguese continental waters, namely seasonal closure when overlapping with the peak of the reproductive season (May and June), and provide valuable scientific support for future conservation and management measures. Full article

(This article belongs to the Special Issue Ecology of Fish: Age, Growth, Reproduction and Feeding Habits)

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15 pages, 3522 KB

Open AccessEditor’s ChoiceArticle

Combined Microplastics and Cadmium Exposure Induces Persistent Gut Microbiota Dysbiosis in Pearl Oyster Pinctada fucata martensii

by Luomin Huang, Yujing Lin, Lintao Liu, Qin Su, Jiaen Liu, Chuangye Yang, Jiaying Yao, Zixin Gao and Yuewen Deng

Fishes 2026, 11(1), 51; https://doi.org/10.3390/fishes11010051 - 14 Jan 2026

Cited by 1 | Viewed by 1004

Abstract

In marine aquaculture environments, microplastics (MPs) and cadmium (Cd) are widespread contaminants that may jointly affect host–microbe interactions. Here, we examined the combined effects of MPs (5 mg/L) and Cd (5 μg/L) on the intestinal microbial community of pearl oysters after a 48 [...] Read more.

In marine aquaculture environments, microplastics (MPs) and cadmium (Cd) are widespread contaminants that may jointly affect host–microbe interactions. Here, we examined the combined effects of MPs (5 mg/L) and Cd (5 μg/L) on the intestinal microbial community of pearl oysters after a 48 h exposure, followed by a 5-day recovery period. Gut microbiota dynamics were characterized using 16S rRNA gene sequencing. Alpha diversity did not vary significantly, whereas beta diversity showed marked alterations in community composition among the different exposure treatments. LEfSe analysis revealed distinct microbial biomarkers and putative pathogens under each treatment: Sulfitobacter in the MPs-alone group; Vibrio and Candidatus_Megaira in the Cd-alone group; and Tenacibaculum, Roseibacillus, and Enterovibrio across different co-exposure and recovery groups. A brief recovery period partially decreased the abundance of certain pathogens (e.g., Vibrio), yet some taxa (e.g., Enterovibrio and Tenacibaculum) remained enriched. These results indicate that exposure to MPs and Cd, whether alone or in combination, disrupts gut microbial homeostasis in pearl oysters by reshaping community structure and promoting the proliferation of potential pathogens, with some disturbances persisting after exposure ceases. Generally, our findings will aid evaluation of the ecological risks of combined pollutants in marine aquaculture systems. Full article

(This article belongs to the Special Issue Biology and Culture of Marine Invertebrates)

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20 pages, 3383 KB

Open AccessEditor’s ChoiceArticle

Gonadal Transcriptome Analysis Identifies Sex-Related Genes and Regulatory Pathways in Spotted Longbarbel Catfish (Hemibagrus guttatus)

by Kun Zhao, Yuanyuan Wang, Yexin Yang, Yi Liu, Chao Liu, Shandian Zhu, Jinhui Sun and Xidong Mu

Fishes 2026, 11(1), 43; https://doi.org/10.3390/fishes11010043 - 9 Jan 2026

Viewed by 1103

Abstract

Hemibagrus guttatus is a large omnivorous fish of significant economic value, listed as a Class II protected species in the National Key Protected Wildlife List in 2021 in China. To provide a theoretical foundation for the artificial breeding of H. guttatus, this [...] Read more.

Hemibagrus guttatus is a large omnivorous fish of significant economic value, listed as a Class II protected species in the National Key Protected Wildlife List in 2021 in China. To provide a theoretical foundation for the artificial breeding of H. guttatus, this study employs high-throughput transcriptome sequencing of testes and ovaries to elucidate the molecular regulatory pathways involved in sex differentiation. Because H. guttatus exhibits no obvious sexual dimorphism even during the breeding season, the distinctive contribution of this study compared with previous gonadal-transcriptomic investigations in other Siluriformes lies not only in documenting sex-biased genes but also in providing a molecular foundation for developing non-lethal sex-identification methods for this morphologically indistinguishable species. A total of 303,192,896 raw reads were obtained, with an effective data rate of 98.4%, indicating high sequencing quality. Differential expression analysis identified 8694 genes, including 6369 upregulated in testes and 2325 upregulated in ovaries. Among these, 88 genes were functionally annotated as sex-related, with 62 testis-biased genes such as spata17, sox9, and dmrt1, and 26 ovary-biased genes including cyp19a, wnt8, and sox12. KEGG pathway enrichment analysis revealed that the TGF-β signaling pathway, insulin secretion, and steroid hormone biosynthesis may play crucial roles in gonadal development and differentiation in H. guttatus. The expression patterns of key genes such as hsd11b1, amh, and insl3 were validated by quantitative real-time PCR, showing consistency with the transcriptome results. These findings lay a molecular foundation for understanding the regulatory mechanisms of sex differentiation in H. guttatus, and provide candidate genes for further investigation into the genetic basis of gonadal development, which is essential for improving artificial reproduction and selective breeding practices. Full article

(This article belongs to the Special Issue Germplasm Resources and Genetic Breeding of Aquatic Animals)

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32 pages, 4378 KB

Open AccessEditor’s ChoiceReview

Precision, Reproducibility, and Validation in Zebrafish Genome Editing: A Critical Review of CRISPR, Base, and Prime Editing Technologies

by Meher un Nissa, Yidong Feng, Shahid Ali and Baolong Bao

Fishes 2026, 11(1), 41; https://doi.org/10.3390/fishes11010041 - 9 Jan 2026

Cited by 1 | Viewed by 3041

Abstract

The rapid evolution of CRISPR/Cas technology has transformed genome editing across biological systems in which zebrafish have emerged as a powerful vertebrate model for functional genomics and disease research. Due to its transparency, genetic similarity to humans, and suitability for large-scale screening, zebrafish [...] Read more.

The rapid evolution of CRISPR/Cas technology has transformed genome editing across biological systems in which zebrafish have emerged as a powerful vertebrate model for functional genomics and disease research. Due to its transparency, genetic similarity to humans, and suitability for large-scale screening, zebrafish is an appropriate system for translating molecular discoveries into biomedical and environmental applications. Thereby, this review highlights the recent progress in zebrafish gene editing, targeting innovations in ribonucleoprotein delivery, PAM-flexible Cas variants, and precision editors. These approaches have greatly improved editing accuracy, reduced mosaicism, and enabled efficient F0 phenotyping. In the near future, automated microinjections, optimized guide RNA design, and multi-omics validation pipelines are expected to enhance reproducibility and scalability. Although recent innovations such as ribonucleoprotein delivery, PAM-flexible Cas variants, and precision editors have expanded the zebrafish genome-editing toolkit, their benefits are often incremental and context-dependent. Mosaicism, allele complexity, and variable germline transmission remain common, particularly in F0 embryos. Precision editors enable defined nucleotide changes but typically exhibit modest efficiencies and locus-specific constraints in zebrafish. Consequently, rigorous validation, standardized workflows, and careful interpretation of F0 phenotypes remain essential. This review critically examines both the capabilities and limitations of current zebrafish gene-editing technologies, emphasizing experimental trade-offs, reproducibility challenges, and realistic use cases. Full article

(This article belongs to the Section Genetics and Biotechnology)

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18 pages, 1939 KB

Open AccessEditor’s ChoiceArticle

Zebrafish Girella zebra (Richardson 1846): Biological Characteristics of an Unexploited Fish Population

by Peter Graham Coulson

Fishes 2026, 11(1), 24; https://doi.org/10.3390/fishes11010024 - 1 Jan 2026

Viewed by 959

Abstract

Kyphosids are prominent members of temperate and subtropical reef fish communities, though many species are not targeted due to their poor eating qualities. This study investigated the biology of the non-targeted zebrafish, Girella zebra, from waters off southern Western Australia. Frequent captures [...] Read more.

Kyphosids are prominent members of temperate and subtropical reef fish communities, though many species are not targeted due to their poor eating qualities. This study investigated the biology of the non-targeted zebrafish, Girella zebra, from waters off southern Western Australia. Frequent captures of small juveniles enabled confirmation of the formation of the first otolith zone, and marginal increment analysis verified the annual formation of opaque zones. Female G. zebra reached a maximum total length and age of 399 mm and 45 years, while males attained 431 mm and 36 years. Girella zebra exhibits a “square” form of growth, as do other Kyphosids, whereby rapid growth occurs during the first 6–8 years, followed by minimal growth throughout a long adult lifespan. Length and age at maturity were 290 mm and 6.7 years for females and 269 mm and 4.9 years for males. Spawning occurs from August to December, and large gonads in both sexes are indicative of spawning in large schools. Natural mortality (M) estimates (females: 0.10–0.15 year⁻¹; males: 0.12–0.18 year⁻¹) exceeded total mortality from catch curves, reflecting that commonly used M estimators are based on heavily fished stocks. This study provides rare biological data for a species unaffected by fishing. Full article

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36 pages, 6672 KB

Open AccessEditor’s ChoiceReview

How May the Increase in Pink Salmon (Oncorhynchus gorbucsha) Cause the Populations of the Atlantic Salmon (Salmo salar) to Decline?

by Marja Keinänen and Pekka J. Vuorinen

Fishes 2026, 11(1), 17; https://doi.org/10.3390/fishes11010017 - 27 Dec 2025

Viewed by 2313

Abstract

Atlantic salmon (Salmo salar) populations in the Arctic River Teno (Tana) and other North Atlantic rivers have declined at the same time as pink salmon (Oncorhynchus gorbuscha) have begun to spawn extensively in these rivers in odd-numbered years. In [...] Read more.

Atlantic salmon (Salmo salar) populations in the Arctic River Teno (Tana) and other North Atlantic rivers have declined at the same time as pink salmon (Oncorhynchus gorbuscha) have begun to spawn extensively in these rivers in odd-numbered years. In the River Teno, especially, the number of one-sea-year Atlantic salmon ascendants has decreased. In this short review, we assess, based on current information, how the abundance of pink salmon may weaken the survival of Atlantic salmon. Our hypothesis is based on recent evidence from Atlantic salmon in the Baltic Sea showing that the high marine lipid content in the diet of Atlantic salmon post-smolts impairs their growth and survival and is manifested in low numbers of ascendants and in poor thiamine (vitamin B1) status in both juvenile and spawning Baltic salmon. The high energy density of lipids increases the need for thiamine in the metabolism, and the high content of highly unsaturated fatty acids (n–3 HUFAs), like docosahexaenoic acid (DHA, 22:6n–3), in marine fish lipids increases the rate of lipid peroxidation, which consumes thiamine as it acts as an antioxidant against lipid peroxidation. The review presents information that could be used in planning possible future research on the topic. Full article

(This article belongs to the Section Biology and Ecology)

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17 pages, 1378 KB

Open AccessEditor’s ChoiceArticle

Extremely Low Sample Size Allows Age and Growth Estimation in a Rare and Threatened Shark

by Peter M. Kyne, Jonathan J. Smart and Grant J. Johnson

Fishes 2026, 11(1), 7; https://doi.org/10.3390/fishes11010007 - 24 Dec 2025

Viewed by 1544

Abstract

Understanding life history parameters is key to assessing demography, biological productivity, and extinction risk of fishes. Age and growth analyses in chondrichthyan fishes (sharks, rays, and ghost sharks) is primarily undertaken through counting vertebral band pairs. For rare, threatened, and protected species such [...] Read more.

Understanding life history parameters is key to assessing demography, biological productivity, and extinction risk of fishes. Age and growth analyses in chondrichthyan fishes (sharks, rays, and ghost sharks) is primarily undertaken through counting vertebral band pairs. For rare, threatened, and protected species such as river sharks (Carcharhinidae; Glyphis), obtaining sufficient vertebrae samples may not be possible. Here we use a very small sample size, selective size-class sampling, back-calculation techniques, and a Bayesian hierarchical model that accounts for repeated measures to provide age and growth information for the Speartooth Shark Glyphis glyphis from which comprehensive sampling is not possible. Ten individuals were selectively sampled from the Adelaide River, Northern Territory, Australia. Bayesian length-at-age models using a combination of informative and uninformative priors in a multi-model framework were applied to the observed and back-calculated data with the sexes combined. Band pair counts produced age estimates of 0–11 years and suggest that age at maturity is possibly >12 years. Most model parameter estimates for length-at-birth (L₀) and asymptotic length (L_∞) were biologically plausible. The Gompertz growth function, applied through a Bayesian hierarchical approach to back-calculated data, provided the best fitting and most biologically appropriate length-at-age parameters: L_∞ = 229.5 cm TL ± (14.6 SE), g_Gom = 0.16 yr⁻¹ ± (0.01 SE), and L₀ = 58.2 cm TL ± (1.4 SE). The results presented here are the first study to apply Bayesian methods to back-calculated length-at-age data while accounting for repeated measures. Full article

(This article belongs to the Special Issue Biology and Conservation of Elasmobranchs)

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41 pages, 1516 KB

Open AccessEditor’s ChoiceReview

Exploring NAD⁺ Biology in Fish: From Cellular Metabolism to Ecological Adaptations and Aquaculture Strategies

by María Ángeles Esteban and Álvaro Sánchez-Ferrer

Fishes 2025, 10(12), 647; https://doi.org/10.3390/fishes10120647 - 15 Dec 2025

Viewed by 2037

Abstract

This review elucidates the foundational principles of nicotinamide adenine dinucleotide (NAD⁺) homeostasis in humans, emphasizing its depletion during aging and in age-associated disorders. Subsequently, the discussion extends to NAD⁺ precursors and their potential therapeutic applications, with insights from research using [...] Read more.

This review elucidates the foundational principles of nicotinamide adenine dinucleotide (NAD⁺) homeostasis in humans, emphasizing its depletion during aging and in age-associated disorders. Subsequently, the discussion extends to NAD⁺ precursors and their potential therapeutic applications, with insights from research using zebrafish as a disease model. This information sheds light on the growing interest in NAD and its metabolism in the medical field and sparks curiosity among researchers focused on fish studies. The review further explores the role of nicotinamide in fish, encompassing core NAD⁺ metabolism, its participation in oxidative stress, environmental challenges, and the mitigation of pollutant-induced toxicity. Additionally, the implications of NAD⁺ in fish neurobiology, immune regulation, host–pathogen interactions, skin, eggs, and post mortem muscle were considered. Dietary modulation of NAD⁺ pathways to enhance growth, immunity, and product quality in aquaculture has also been highlighted. This review highlights the significance of NAD⁺ metabolism in fish biology, covering cellular energy production, physiological processes, and environmental adaptation, and proposes targeting NAD⁺-related pathways as a strategy for aquaculture and fish health management. Full article

(This article belongs to the Special Issue Feature Papers by Fishes’ Editorial Board Members)

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15 pages, 1740 KB

Open AccessEditor’s ChoiceArticle

Spatiotemporal and Environmental Effects on Demersal Fishes Along the Nearshore Texas Continental Shelf

by Erin M. Johnson, Fernando Martinez-Andrade, P. Santiago Domínguez-Sánchez, Aurora Gaona-Hernandez, Chengxue Li and R. J. David Wells

Fishes 2025, 10(12), 632; https://doi.org/10.3390/fishes10120632 - 9 Dec 2025

Cited by 1 | Viewed by 1349

Abstract

The goal of this study was to analyze data from a 10-year bottom longline survey to examine spatial, temporal, and environmental effects on demersal fishes along the Texas coast within the northwestern Gulf of Mexico. Generalized additive models (GAMs) and generalized linear models [...] Read more.

The goal of this study was to analyze data from a 10-year bottom longline survey to examine spatial, temporal, and environmental effects on demersal fishes along the Texas coast within the northwestern Gulf of Mexico. Generalized additive models (GAMs) and generalized linear models (GLMs) were employed to evaluate trends and patterns in species composition (species richness and species diversity), relative abundance, and presence probability of fish species in the Texas region of the northwestern Gulf of Mexico. Temperature, salinity, and dissolved oxygen were the most influential variables driving richness, diversity, and abundance of demersal fish assemblages. The community was dominated by six species that represent 93% of total catch: Rhizoprionodon terraenovae (Atlantic sharpnose shark), Bagre marinus (gafftopsail catfish), Sciaenops ocellatus (red drum), Carcharhinus limbatus (blacktip shark), Carcharhinus brevipinna (spinner shark), and Carcharhinus leucas (bull shark). Analyses of dominant species revealed that multiple factors modulated their presence probability, with temperature and dissolved oxygen as common environmental drivers among species. Findings from the present study suggest that the composition and abundance of demersal fish assemblages were shaped by key environmental drivers. Full article

(This article belongs to the Section Biology and Ecology)

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23 pages, 6175 KB

Open AccessEditor’s ChoiceArticle

Danger! Stay Alert: The Role of Skein Cells in the Evolution of the Sea Lamprey (Petromyzon marinus, Linnaeus 1758)

by Alessio Alesci, Sebastian Marino, Stefania Fiorentino, Anthea Miller, Simon Palato, Sergio Famulari, Giorgia Pia Lombardo, Roberto Ferreira Artoni and Eugenia Rita Lauriano

Fishes 2025, 10(12), 605; https://doi.org/10.3390/fishes10120605 - 26 Nov 2025

Cited by 1 | Viewed by 1079

Abstract

When it comes to predation, alarm signals enable individuals to assess risks and modulate their behavior accordingly. These signals, often chemical in aquatic environments, can be recognized across species boundaries and are typically released through injury-induced mechanisms in response to predation. While extensively [...] Read more.

When it comes to predation, alarm signals enable individuals to assess risks and modulate their behavior accordingly. These signals, often chemical in aquatic environments, can be recognized across species boundaries and are typically released through injury-induced mechanisms in response to predation. While extensively documented in teleosts, particularly those possessing epidermal club cells, such mechanisms remain poorly understood in more basal vertebrates, such as lampreys, which possess unique epidermal structures called skein cells. The present study investigated the potential role of skein cells in the immune and alarm signaling systems of the sea lamprey (Petromyzon marinus), given their strategic location in the skin and distinctive ultrastructural characteristics, such as polarized nuclei and tonofilament-rich basal cytoplasm. Although originally misidentified as club cells, skein cells may be involved in mucus secretion and the release of compounds such as sialic acid and glycoconjugates, which provide defense against aquatic pathogens. This study employed histomorphological analysis, immunoperoxidase labeling, confocal microscopy, bioinformatics, and quantitative and statistical analysis to investigate the hypothesis that skein cells contribute to anti-predator defense via the release of alarm substances. These findings provide new insights into the evolutionary origins and functional diversity of chemical signaling in the early vertebrate. Full article

(This article belongs to the Section Biology and Ecology)

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23 pages, 10985 KB

Open AccessEditor’s ChoiceArticle

Comparative Physiological Profiling of Abalone (Haliotis iris): Insights from Wild and Aquaculture Broodstock

by Ruchira S. Sawant, Leonie Venter, Awanis Azizan, Jinchen Guo, Jack Carter, Natalia Bullon, Tony Chen, Joanna S. Copedo, Norman L. C. Ragg, Armagan Sabetian and Andrea C. Alfaro

Fishes 2025, 10(11), 566; https://doi.org/10.3390/fishes10110566 - 5 Nov 2025

Cited by 2 | Viewed by 1924

Abstract

New Zealand abalone (Haliotis iris) holds ecological, economic, and cultural value, with wild stocks supporting fisheries and an emerging aquaculture industry. Wild-caught adult abalone are often used as broodstock, but captivity can affect spawning and offspring quality. This study is the [...] Read more.

New Zealand abalone (Haliotis iris) holds ecological, economic, and cultural value, with wild stocks supporting fisheries and an emerging aquaculture industry. Wild-caught adult abalone are often used as broodstock, but captivity can affect spawning and offspring quality. This study is the first to profile wild and farmed H. iris broodstock using histology, proximate composition, microbiome, and metabolomics analyses. Histology showed higher gonadal abnormalities in farmed abalone, while wild abalone exhibited increased ciliates in their gills, indicating richer marine–microorganism interactions. Microbiome analyses revealed a higher microbial richness and diversity in the buccal cavity of wild abalone. The core microbiota phyla across both groups included Proteobacteria, Bacteroidota, Campylobacterota, Fusobacteria, and Firmicutes. Proximate analyses showed higher muscle protein in farmed abalone, while gonadal tissue partitioned by sex showed higher fat in females and higher protein in males. Metabolomics revealed altered amino acid metabolism in the adductor muscle, carboxylic acid metabolism in the gonad, and fatty acid metabolism in the foot. This investigation expands our understanding of the physiological and microbial differences between wild and farmed abalone, showing altered gonad and muscle conditions from prolonged captivity and highlighting the need for greater microbial diversity in cultured stocks. Full article

(This article belongs to the Section Physiology and Biochemistry)

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17 pages, 1438 KB

Open AccessEditor’s ChoiceArticle

Impact of Stocking Density on Growth, Feeding Behavior, and Flesh Quality of Largemouth Bass (Micropterus salmoides) in Coupled Aquaponic Systems

by Marco Birolo, Veronica Trabacchin, Paolo Sambo, Stefano Triolone and Carlo Nicoletto

Fishes 2025, 10(11), 552; https://doi.org/10.3390/fishes10110552 - 2 Nov 2025

Cited by 1 | Viewed by 2816

Abstract

Stocking density is a key driver of performance in aquaponics, affecting both fish welfare and crop yield. This study evaluated the impact of three initial stocking densities (3.1, 4.1, and 6.2 kg/m³) on survival, growth, feeding behavior, carcass and filet quality [...] Read more.

Stocking density is a key driver of performance in aquaponics, affecting both fish welfare and crop yield. This study evaluated the impact of three initial stocking densities (3.1, 4.1, and 6.2 kg/m³) on survival, growth, feeding behavior, carcass and filet quality of largemouth bass (Micropterus salmoides), as well as on the yield of lettuce (Lactuca sativa), sweet basil (Ocimum basilicum), and Swiss chard (Beta vulgaris var. cicla) cultivated in vertical coupled aquaponic units. A total of 184 fish (109 ± 28 g) were reared for 176 days in nine independent recirculating systems. Fish reared at the lowest density achieved the highest final live weight and specific growth rate, with a better feed conversion ratio, whereas performance declined at higher densities despite similar survival rates. Feeding behavior was generally consistent across groups, although feed intake rate was reduced at the highest density. Carcass and filet quality traits were unaffected by stocking density. Vegetable yield was enhanced by higher fish biomass, with significant increases in lettuce production and a positive trend for basil. These findings indicate that intermediate stocking densities may represent the most sustainable compromise, ensuring fish welfare and acceptable growth while supporting efficient plant production in largemouth bass–based aquaponics. Full article

(This article belongs to the Special Issue Fish Health and Welfare in Aquaculture and Research Settings)

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15 pages, 254 KB

Open AccessEditor’s ChoiceArticle

Comparative Effects of Arthrobacter bussei-Derived Powder and Probiotics, and Haematococcus pluvialis Powder, as Dietary Supplements for Pacific White Shrimp (Litopenaeus vannamei)

by Soohwan Kim, Hyun Mi Jung, Seunghan Lee and Hyon-Sob Han

Fishes 2025, 10(11), 543; https://doi.org/10.3390/fishes10110543 - 24 Oct 2025

Cited by 1 | Viewed by 1154

Abstract

This study evaluated how dietary supplementation with Haematococcus pluvialis powder (HPP), Arthrobacter bussei powder (ABP), and A. bussei probiotics affects growth, whole-body composition, non-specific immunity, antioxidant capacity, and nutrient digestibility in Pacific white shrimp (Litopenaeus vannamei). Juvenile shrimps were fed for [...] Read more.

This study evaluated how dietary supplementation with Haematococcus pluvialis powder (HPP), Arthrobacter bussei powder (ABP), and A. bussei probiotics affects growth, whole-body composition, non-specific immunity, antioxidant capacity, and nutrient digestibility in Pacific white shrimp (Litopenaeus vannamei). Juvenile shrimps were fed for 8 weeks with five diets: a control diet (CON), H. pluvialis powder (HPP, 1%), A. bussei powder (ABP, 1%), or A. bussei probiotics at 10⁵ (ABL) or 10⁸ (ABH) CFU g⁻¹ feed. Shrimp fed the ABP diet exhibited the highest final body weight, weight gain, and protein efficiency ratio, with a significantly improved feed conversion ratio than that of CON, ABL, and ABH groups. The HPP group exhibited significantly better growth than that of the control. Regarding immunity and antioxidant responses, lysozyme and phenoloxidase specific activities, as well as glutathione peroxidase and superoxide dismutase specific activities, were significantly enhanced in shrimp fed ABP and HPP diets, whereas malondialdehyde levels were significantly reduced compared with those in CON. Apparent crude protein digestibility was significantly higher in all supplemented diets than those in the CON group, with ABP showing the highest value. ABP and HPP supplementation improved growth, protein digestibility, and immune-antioxidant responses in L. vannamei, whereas probiotic forms showed limited effects. ABP is a superior functional feed additive than its probiotic form for enhancing productivity and health in shrimp aquaculture. Full article

(This article belongs to the Section Nutrition and Feeding)

14 pages, 1723 KB

Open AccessEditor’s ChoiceArticle

High Connectivity in the Deep-Water Pagellus bogaraveo: Phylogeographic Assessment Across Mediterranean and Atlantic Waters

by Martina Spiga, Giusy Catalano, Federica Piattoni, Alice Ferrari, Carolina Johnstone, Kenza Mokhtar-Jamaï, Montse Pérez, Fabio Fiorentino, Manuel Hidalgo and Alessia Cariani

Fishes 2025, 10(10), 527; https://doi.org/10.3390/fishes10100527 - 17 Oct 2025

Viewed by 1039

Abstract

The Blackspot Seabream, Pagellus bogaraveo, is a commercially valuable species widely distributed in the northeastern Atlantic and Mediterranean. Its biology makes it vulnerable to overfishing, but its population structure and ontogenetic migration strategy remain unclear. Building on previous work based on microsatellite [...] Read more.

The Blackspot Seabream, Pagellus bogaraveo, is a commercially valuable species widely distributed in the northeastern Atlantic and Mediterranean. Its biology makes it vulnerable to overfishing, but its population structure and ontogenetic migration strategy remain unclear. Building on previous work based on microsatellite markers, we expanded the investigation by analysing the mitochondrial Control Region (CR) to complement nuclear data. We analysed 199 specimens from 13 sites and combined the new CR sequences with 129 published records to achieve the broadest coverage in terms of biogeographic and genetic data. We calculated genetic diversity and performed AMOVA, pairwise ΦST comparisons, and multivariate analyses. Eighty-eight haplotypes were identified, showing high haplotype diversity (Hd = 0.767–0.945) and moderate nucleotide diversity (π = 0.0026–0.0054). Most genetic variation occurred within populations, and overall analyses indicated genetic homogeneity. However, pairwise analysis and AMOVA confirmed significant differentiation of the Azores population. These results confirm extensive genetic connectivity throughout the Atlantic–Mediterranean range of P. bogaraveo, likely due to a combination of large larval dispersal and a common spawning migration strategy, but identify the Azores as a genetically distinct unit. This highlights the need to consider both large-scale connectivity and local divergence in fisheries management. Full article

(This article belongs to the Special Issue Conservation and Population Genetics of Fishes)

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18 pages, 1665 KB

Open AccessEditor’s ChoiceArticle

Anthropogenic Microparticles in Aquaculture and Wild Fish: A Case Study of Three Commercially Important Species in the Eastern Mediterranean

by Aikaterini Kostoula, Eugenia Moschou-Kounopioti, Niki Milatou and Persefoni Megalofonou

Fishes 2025, 10(10), 492; https://doi.org/10.3390/fishes10100492 - 2 Oct 2025

Cited by 1 | Viewed by 1044

Abstract

Over the past decade, increasing attention has been given to the impacts of anthropogenic microparticle (AM) pollution on marine ecosystems. This study investigates AM ingestion in three commercially important fish species—Sparus aurata Linnaeus, 1758, Dicentrarchus labrax Linnaeus, 1758, and Boops boops Linnaeus, [...] Read more.

Over the past decade, increasing attention has been given to the impacts of anthropogenic microparticle (AM) pollution on marine ecosystems. This study investigates AM ingestion in three commercially important fish species—Sparus aurata Linnaeus, 1758, Dicentrarchus labrax Linnaeus, 1758, and Boops boops Linnaeus, 1758—collected from both wild and farmed populations in Greek marine and lagoon environments. A total of 60 specimens were sampled from the Messolonghi Lagoon, Rhodes Island, and the Cyclades. AM were detected in 61.7% of the individuals analyzed. The mean number of ingested items per individual was 1.1 ± 1.2 in B. boops, 1.0 ± 1.7 in wild and 2.3 ± 2.1 in farmed S. aurata, and 2.5 ± 3.1 in wild and 3.6 ± 2.2 in farmed D. labrax. Ingestion ranged from 0 to 9 items per fish. No significant correlations were found between fish size and either the number or the size of ingested AM in any species. The ingested AM were primarily classified as fibers and fragments, displaying variability in size and color. Black was the dominant color across all species, followed by red and blue, while yellow was rarely observed. A statistically significant difference in the mean size of AM was recorded between wild and farmed D. labrax, whereas no such difference was observed for S. aurata. Overall, these findings provide new evidence on AM contamination in seafood species and highlight their occurrence in both natural and aquaculture environments of the eastern Mediterranean. Full article

(This article belongs to the Section Biology and Ecology)

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15 pages, 478 KB

Open AccessEditor’s ChoiceArticle

Nitrogen Budget in Yellow-Tail Lambari Monoculture and Integrated Aquaculture

by Dalton Belmudes, Andre Z. Boaratti, Paulo V. L. Mantoan, Aline M. Marques, Julia R. C. Ferreira, Patricia Moraes-Valenti, Dallas L. Flickinger and Wagner C. Valenti

Fishes 2025, 10(10), 480; https://doi.org/10.3390/fishes10100480 - 26 Sep 2025

Cited by 3 | Viewed by 1177

Abstract

This study quantified nitrogen (N) inputs by water, feed, animals, and atmospheric gas and outputs by water, harvested animals, sediments, and gas emissions in earthen ponds used for the monoculture and integrated cultures of yellow-tail lambari (Astyanax lacustris), Amazon River prawn [...] Read more.

This study quantified nitrogen (N) inputs by water, feed, animals, and atmospheric gas and outputs by water, harvested animals, sediments, and gas emissions in earthen ponds used for the monoculture and integrated cultures of yellow-tail lambari (Astyanax lacustris), Amazon River prawn (Macrobrachium amazonicum), and curimbata (Prochilodus lineatus), and evaluated whether epibenthic species improve N retention in harvested biomass. Three systems with four replicates were tested, lambari monoculture (L), lambari–prawn (LP), and lambari–prawn–curimbata (LPC), stocked at 50, 25, and 13 individuals m⁻², respectively. Feed N was the major input (67–75%), followed by inlet water (19–30%). Harvested biomass represented 20–23% of total outputs, sediments 25–33%, and gaseous emissions 7–29%, while outlet water contributed <3%. N lost through seepage was highest in L (70.5 ± 22.9 kg N ha⁻¹). N₂ ebullition increased with benthic species, from 10.4 ± 10.6 kg N ha⁻¹ (L) to 72.1 ± 32.4 kg N ha⁻¹ (LPC). N recovered in lambari was 43.2 ± 7.4 kg N ha⁻¹ in LPC, 36 ± 8.6 in L, and 33 ± 5.6 in LP. Considering all species, recovery of dietary N increased from 20.0 ± 4.3% (L) to 35.0 ± 5.9% (LPC), and recovery from all inputs rose from 13.0 ± 2.2% to 18.0 ± 3.4%. Integrated systems, particularly LPC, enhanced N retention in biomass and reduced environmental losses. Full article

(This article belongs to the Special Issue Integrated Multi-Trophic Aquaculture (IMTA))

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