Fishes

23 pages, 21519 KB

Open AccessArticle

Bioaccumulation of Trace Elements in the Most Commercial Fish in the Southern Black Sea and Risk Estimates Related to Their Consumption

by Levent Bat, Süleyman Özdemir, Zekiye Birinci Özdemir and Ayşah Öztekin

Fishes 2026, 11(5), 295; https://doi.org/10.3390/fishes11050295 - 15 May 2026

Abstract

This study evaluates the accumulation of trace elements (Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Hg, and Pb) in the muscle tissues of six commercially important fish species (Scophthalmus maximus, Merlangius merlangus, Mullus ponticus, Trachurus mediterraneus [...] Read more.

This study evaluates the accumulation of trace elements (Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Hg, and Pb) in the muscle tissues of six commercially important fish species (Scophthalmus maximus, Merlangius merlangus, Mullus ponticus, Trachurus mediterraneus, Engraulis encrasicolus, and Sprattus sprattus) harvested from multiple locations across the Sinop and Samsun coasts of the southern Black Sea during the 2023–2025 fishing seasons to assess potential human health risks. Element concentrations were quantified using inductively coupled plasma mass spectrometry (ICP-MS) and compared against national and international food safety standards. Results indicated that essential elements, particularly Fe and Zn, exhibited the highest concentrations, while Co and potentially toxic elements (Cd, Pb, As, and Hg) remained at lower levels. Although significant geographical variations in accumulation were observed between sampling locations, inter-species differences were relatively minor. Human health risk assessments, including Estimated Daily Intake (EDI), Target Hazard Quotient (THQ), and Carcinogenic Risk (CR), revealed that all THQ values were well below 1, indicating no non-carcinogenic concerns. Furthermore, CR values for As, Cr, and Pb fell within the acceptable range (10⁻⁶ to 10⁻⁴) defined by the U.S. EPA. Consequently, fish consumption from these regions poses no unacceptable risk, though localized element elevations suggest a need for enhanced environmental monitoring of pollution sources. Full article

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

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18 pages, 3493 KB

Open AccessArticle

Gut Microbiota and Metabolome Differences Between Fast- and Slow-Growing Brass Gudgeon (Coreius heterodon)

by Yafan Dai, Leiming Zhang, Xingyu Ma, Bing Xie, Xueying Pei, Xiaolan Shi, Jie Mei, Tao Wang, Guoqin Zhou and Wei Liu

Fishes 2026, 11(5), 294; https://doi.org/10.3390/fishes11050294 - 15 May 2026

Abstract

The gut microbiota plays a crucial role in regulating fish growth. In this study, we performed 16S rRNA sequencing and metabolomics to compare the gut microbiota and metabolic profiles of fast-growing (FG) and slow-growing (SG) brass gudgeon (Coreius heterodon) from the [...] Read more.

The gut microbiota plays a crucial role in regulating fish growth. In this study, we performed 16S rRNA sequencing and metabolomics to compare the gut microbiota and metabolic profiles of fast-growing (FG) and slow-growing (SG) brass gudgeon (Coreius heterodon) from the same family, reared under identical conditions for 12 months. Our results revealed that there was no significant difference in the overall gut microbiota structure between FG and SG groups, but significant differences were observed at specific phylum and genus levels. The FG group harbored a greater abundance of potential probiotics (e.g., Prevotella, Lactobacillus, and Lachnospiraceae NK4A136_group), while opportunistic pathogens such as Klebsiella and Pseudomonas were less abundant. Metabolomics analysis identified 136 differential metabolites, among them, 61 were upregulated and 75 were downregulated in the FG group, with higher levels of phosphatidylcholine, acylcarnitine, and amino acid derivatives in the FG group. KEGG pathway analysis showed enrichment of butanoate metabolism, tryptophan metabolism, and pyrimidine metabolism in the FG group. Spearman correlation analysis indicated that specific gut microbiota was significantly correlated with metabolites involved in energy metabolism, gut homeostasis, and oxidative balance. These findings revealed associations between specific gut microbiota, gut metabolites, and growth performance in brass gudgeon. Although overall community structure did not differ significantly between groups, the compositional and metabolic shifts observed suggest that the gut microbiota–metabolite association might be linked to growth variation. This study provided new insights into the microbiota–metabolite–growth axis of brass gudgeon and offers valuable reference information for the development of specialized probiotic feeds for this species. Full article

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23 pages, 4364 KB

Open AccessArticle

Integrative Transcriptome and GWAS Analyses Reveal Growth-Associated Molecular Architecture in Pacific Abalone (Haliotis discus hannai)

by Hyejung Jung, Eun Soo Noh, Hyejin Kim, Hee-Bok Park, Young-Su Seo, In Jun Hwang, Hee Jeong Kong, Jung-Ha Kang and Jungwook Park

Fishes 2026, 11(5), 293; https://doi.org/10.3390/fishes11050293 - 15 May 2026

Abstract

Pacific abalone (Haliotis discus hannai) is a widely cultured and economically important abalone species in aquaculture yet improving growth performance remains a major challenge for stable production. To clarify the molecular architecture associated with growth performance in Pacific abalone, we integrated [...] Read more.

Pacific abalone (Haliotis discus hannai) is a widely cultured and economically important abalone species in aquaculture yet improving growth performance remains a major challenge for stable production. To clarify the molecular architecture associated with growth performance in Pacific abalone, we integrated transcriptome and genome-wide association study (GWAS) data from high-growth and low-growth groups showing significant growth differences. Transcriptome profiles from hepatopancreas and mantle tissues were used to construct a co-expression network of 43,125 genes, summarized into 22 modules associated with tissue specificity and growth-related variation. In parallel, analysis of a custom 60K SNP array identified 67 significant growth-associated SNPs. Integration of these GWAS signals into the co-expression network revealed a core module most strongly correlated with growth index and enriched for SNP-derived candidate genes. Functional enrichment indicated that the core module was associated with proteostasis and growth-related signaling pathways, including insulin, Ras, and MAPK signaling. Protein–protein interaction analysis further identified 11 hub genes with high intramodular connectivity and direct interactions with SNP-derived genes, most of which participate in receptor-mediated and intracellular growth-regulatory functions. These findings provide an integrated molecular framework for growth performance in Pacific abalone and candidate targets for future molecular breeding strategies. Full article

(This article belongs to the Special Issue Applications of Genome-Based Technologies in Aquaculture)

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11 pages, 743 KB

Open AccessArticle

Preference for Natural Stimuli in Juvenile Guppies

by Chiara Varracchio, Cristiano Bertolucci, Giorgio Bertorelle and Tyrone Lucon-Xiccato

Fishes 2026, 11(5), 292; https://doi.org/10.3390/fishes11050292 - 14 May 2026

Abstract

Drawing on the well-documented preference for natural and highly biodiverse environments in humans, it has been proposed that other animals may also recognise and show interest in natural stimuli. If widespread across animals, such a preference could have important evolutionary and welfare implications. [...] Read more.

Drawing on the well-documented preference for natural and highly biodiverse environments in humans, it has been proposed that other animals may also recognise and show interest in natural stimuli. If widespread across animals, such a preference could have important evolutionary and welfare implications. However, we currently lack investigations of this preference outside humans. To begin filling this gap, we examined whether juvenile guppies (Poecilia reticulata) exhibit a spontaneous preference for natural stimuli. In a dichotomous choice test, guppies were given the opportunity to choose between an environment containing live aquatic plants and one with structurally similar, in shape and size, artificial plants. After habituation to the testing apparatus, guppies spent significantly more time in the environment with live plants, suggesting a preference for natural stimuli. This supports the idea that, beyond humans, other animals may also be capable of recognizing and responding to natural stimuli. Full article

(This article belongs to the Section Physiology and Biochemistry)

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28 pages, 10868 KB

Open AccessArticle

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

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 (mean 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 AccessArticle

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

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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21 pages, 1017 KB

Open AccessReview

Monoterpenes as Natural Anesthetics to Mitigate Stress in Fish: Advances Using the Zebrafish Larvae Model

by Raquel S. F. Vieira, Cláudia A. Rocha, Carlos A. S. Venâncio and Luís M. Félix

Fishes 2026, 11(5), 289; https://doi.org/10.3390/fishes11050289 - 13 May 2026

Abstract

During production, fish are exposed to multiple environmental, physiological, and physical stressors, which compromise development, productivity, and welfare and urge the implementation of effective and safe stress-mitigating strategies, particularly during early developmental stages. Larval zebrafish (Danio rerio) constitute a powerful model [...] Read more.

During production, fish are exposed to multiple environmental, physiological, and physical stressors, which compromise development, productivity, and welfare and urge the implementation of effective and safe stress-mitigating strategies, particularly during early developmental stages. Larval zebrafish (Danio rerio) constitute a powerful model for studying acute stress responses due to the numerous advantages they offer, such as developmental transparency, a conserved hypothalamic–pituitary–interrenal (HPI) axis, and suitability for high-throughput screening. This review examines the potential of natural monoterpenes as stress-reducing compounds and compares their performance with conventional synthetic anesthetics. Evidence from vortex-flow stress paradigms, behavioral profiling and biochemical assays shows that acute stress in zebrafish larvae triggers metabolic disruption, behavioral hyperactivity and enzyme imbalance, with cortisol responses depending on stimulus intensity. Monoterpenes such as thymol and menthol consistently reduce stress-induced hyperactivity, support redox homeostasis and display favorable safety profiles at low doses and short exposures. Nevertheless, as research into these substances is still recent, evidence of any potential adverse effects is still limited. Although individual monoterpenes may act on different subsets of molecular targets, their multimodal mechanisms, including gamma-aminobutyric acid (GABA)ergic enhancement, voltage-gated ion channel and transient receptor potential (TRP) modulation, suggest broader and potentially safer actions compared to single-target anesthetics as tricaine methane sulfonate (MS-222). Collectively, these findings suggest that monoterpenes offer promising natural alternatives for stress mitigation in aquaculture and the refinement of research procedures involving early life stages. Full article

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

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25 pages, 9577 KB

Open AccessArticle

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

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)

13 pages, 913 KB

Open AccessArticle

Biochemical Properties of Collagen from Four Flatfish Species in Cold Area: In Relation to Physiological Temperature and Amino Acid Composition

by Tetsuro Sugai, Katsuji Morioka and Kohsuke Adachi

Fishes 2026, 11(5), 287; https://doi.org/10.3390/fishes11050287 - 12 May 2026

Abstract

Collagen (ASC) was purified from four flatfish species (Greenland halibut, blackfin flounder, stone flounder, and slime flounder) collected from a cold area in Japan to investigate their biochemical properties. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis pattern, Fourier transform infrared spectroscopy, and circular dichroism analysis [...] Read more.

Collagen (ASC) was purified from four flatfish species (Greenland halibut, blackfin flounder, stone flounder, and slime flounder) collected from a cold area in Japan to investigate their biochemical properties. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis pattern, Fourier transform infrared spectroscopy, and circular dichroism analysis revealed the typical structure of type I collagen. The denaturation temperature (Td) of ASC positively correlated with the physiological temperature (Tp) using previously reported data, which were obtained from fish (a total of 32 species). In this study, the lowest hydroxyproline (Hyp)/Pro/imino acid (Pro + Hyp) content was observed in Greenland halibut ASC (Tp is lowest), whereas the highest Ser content was observed in slime flounder ASC (Tp is highest). Using the data obtained from a previous study, a positive/negative correlation could be found between Td and Hyp/Ser, which is consistent with our previous reports. The Pro content in the present data followed the pattern of Hyp but exceeded the value predicted from Td by approximately 30 residues. These results may suggest that the collagen extracted from four flatfish in the cold area adopted decreasing imino acid content and increasing serine content for their adaptation. Full article

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

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12 pages, 245 KB

Open AccessEditorial

Challenges of Fishery Biology and Fish Population Dynamics in Fisheries Management

by María de Lourdes Jiménez-Badillo

Fishes 2026, 11(5), 286; https://doi.org/10.3390/fishes11050286 - 11 May 2026

Abstract

More than 30,000 species of bony fishes, sharks and rays have been identified worldwide [...] Full article

(This article belongs to the Special Issue The Roles of Fishery Biology and Fish Population Dynamics in Fisheries Management)

13 pages, 2268 KB

Open AccessArticle

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

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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14 pages, 596 KB

Open AccessArticle

Dietary Glycerides of Short- and Medium-Chain Fatty Acids Modulate Intestinal Barrier and Protect Against Vibrio anguillarum in Juvenile Gilthead Sea Bream (Sparus aurata)

by Daniel Montero, Samira Sarih, Marta Carvalho, Félix Acosta, Luís Monzón-Atienza, Alvaro Gordillo, Ehab Aboelsaadat and Silvia Torrecillas

Fishes 2026, 11(5), 284; https://doi.org/10.3390/fishes11050284 - 10 May 2026

Abstract

As aquaculture adopts more sustainable feed formulations, interest in functional feed additives has grown to help mitigate the health and performance challenges associated with low-marine-ingredient diets. This study evaluated the effects of dietary supplementation with a commercial blend of mono-, di-, and triglycerides [...] Read more.

As aquaculture adopts more sustainable feed formulations, interest in functional feed additives has grown to help mitigate the health and performance challenges associated with low-marine-ingredient diets. This study evaluated the effects of dietary supplementation with a commercial blend of mono-, di-, and triglycerides of short- and medium-chain fatty acids (SCFAs and MCFAs; BalanGUT™ AQ P, BASF) on growth, health, and disease resistance to Vibrio anguillarum in juvenile gilthead sea bream (Sparus aurata) fed practical low fishmeal and fish oil diets. Over an 8-week trial, fish were fed diets containing 0.3%, 0.5%, or 1% of a glyceride blend of SCFAs and MCFAs (BalanGUT™ AQ P) or a Control diet without functional additive supplementation. Growth performance and feed utilization were not affected by the supplementation of SCFAs/MCFAs glycerides, although non-significant trends (p > 0.05) toward improved specific growth rate (up to 12%) and reduced feed conversion ratio (up to 17%) were observed in sea bream fed supplemented diets, particularly during the 4 initial weeks and at the highest inclusion level (1%). Moderate (0.5%) and high (1%) supplementation levels of SCFAs and MCFAs significantly improved survival following Vibrio anguillarum challenge, despite no significant changes being observed in general systemic innate immune markers, such as serum lysozyme or ACH50 activities. SCFAs/MCFAs supplementation, particularly at 0.3% or 0.5%, also modulated intestinal morphology, including thinner submucosa and smaller goblet cell area in the posterior intestine, suggestive of a more homeostatic mucosa and reduced basal inflammation when feeding a low-FM/FO-based diet. These results suggest that the protective effects of this SCFAs/MCFAs glyceride blend are mediated primarily through local rather than systemic immune modulation. Overall, this study supports the use of functional SCFAs and MCFAs glyceride blends as a functional strategy to promote resilience and health in fish fed sustainable, low-marine-ingredient diets. Full article

(This article belongs to the Special Issue Advancing Aquatic Animals Nutrition: Functional Additives and Physiological Regulation)

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25 pages, 4230 KB

Open AccessArticle

Optimization of Aeration Tube Configuration Considering the Efficiency of Waste Collection and Water Mixing in Aquaculture Tanks

by Can Cui, Dezhen Li, Fuzhi Zu, Dejun Feng, Xiaoyu Qu and Yi Tao

Fishes 2026, 11(5), 283; https://doi.org/10.3390/fishes11050283 - 9 May 2026

Abstract

Proper configuration of aeration tubes is crucial for improving water quality and promoting the welfare and growth of cultured organisms in Recirculating Aquaculture Systems (RASs). To investigate the effects of aeration tube shapes (arc-shaped, disc-shaped, and linear-shaped) and positions (d = r [...] Read more.

Proper configuration of aeration tubes is crucial for improving water quality and promoting the welfare and growth of cultured organisms in Recirculating Aquaculture Systems (RASs). To investigate the effects of aeration tube shapes (arc-shaped, disc-shaped, and linear-shaped) and positions (d = r, 1/2r) on performance, this study conducted experiments in a circular RAS tank. Methodologically, feed pellets were used to simulate solid waste, while ink was added to visualize the flow field, and mixing performance was quantitatively assessed using the spatial distribution uniformity. The results indicated that without aeration, the physical presence of the tubes affected waste collection but had minimal impact on water mixing. Under aeration conditions, placing tubes at d = 1/2r instead of d = r resulted in more efficient waste collection and improved water mixing. Waste collection performance was ranked as arc-shaped > disc-shaped > linear-shaped, whereas water mixing performance ranked linear-shaped > arc-shaped > disc-shaped. It is therefore recommended to place arc-shaped aeration tubes at d = 1/2r to achieve optimal overall performance. These findings provide valuable baseline insights into the selection and placement of aeration devices, offering preliminary practical guidance for aquaculture engineering. Full article

(This article belongs to the Section Sustainable Aquaculture)

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22 pages, 4992 KB

Open AccessArticle

Impact of Exposure Routes of Copper Oxide Nanoparticles in the Clam Ruditapes decussatus

by Maria J. Bebianno, Mustafa Tuncsoy, Thiago L. Rocha, Tania Gomes and Taina Garcia

Fishes 2026, 11(5), 282; https://doi.org/10.3390/fishes11050282 - 9 May 2026

Abstract

The increasing production of diverse applications of engineered nanoparticles along with their potential release into the marine environment from both point and diffuse sources have become a significant concern for ocean health. Due to their unique physical properties, particularly their high surface-to-volume ratio, [...] Read more.

The increasing production of diverse applications of engineered nanoparticles along with their potential release into the marine environment from both point and diffuse sources have become a significant concern for ocean health. Due to their unique physical properties, particularly their high surface-to-volume ratio, these nanoparticles can exhibit enhanced bioavailability and toxicity to marine biota. Copper oxide nanoparticles (CuO NPs) are especially prevalent due to their wide range of commercial applications. In the aquatic environment, these nanoparticles typically become part of colloidal fraction and are subjected to physicochemical transformations, leading to the formation of aggregates that eventually sink and deposit onto the bottom substrate. Therefore, sediments, in addition to the water column, act as the primary route of exposure to benthic organisms. The clam Rudipates decussatus is a marine suspension-feeder of great ecological and economic importance in Europe. Ruditapes decussatus were exposed to CuO NPs (10 μg L⁻¹) or an equivalent concentration of ionic copper (Cu²⁺) in both water and water/sediments matrices for 15 days to compare the toxicological impact of different exposure routes. Copper accumulation was monitored in both gills and digestive gland, alongside various biomarkers of susceptibility, exposure, and damage. The results revealed distinct uptake patterns that were dependent on the exposure routes, the chemical form of the metal and the specific tissue responses. Highlighting the complex impact of these contaminants on marine biodiversity. Full article

(This article belongs to the Section Environment and Climate Change)

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23 pages, 17215 KB

Open AccessArticle

Comparative In Vitro Bioactivity of Traditional Aqueous and Alcoholic Preparations of Arnica (Chiliadenus glutinosus): Effects on Marine Fish Pathogens, PLHC1 Cells and Gilthead Seabream (Sparus aurata) Leucocytes

by Jose Carlos Campos-Sánchez, Francisco A. Guardiola and María Ángeles Esteban

Fishes 2026, 11(5), 281; https://doi.org/10.3390/fishes11050281 - 9 May 2026

Abstract

Arnica (Chiliadenus glutinosus (L.) Fourr.) is an endemic plant widely used in Spanish traditional medicine as infusions and alcoholic macerates for different ailments. Despite this use, information about the biological activity of these preparations in fish-related models is scarce. In the present [...] Read more.

Arnica (Chiliadenus glutinosus (L.) Fourr.) is an endemic plant widely used in Spanish traditional medicine as infusions and alcoholic macerates for different ailments. Despite this use, information about the biological activity of these preparations in fish-related models is scarce. In the present study, the arnica extract bioactivity assay evaluated aqueous, ethanolic, and methanolic extracts at different doses (0, 0.001, 0.01, 0.125, 0.25, 0.5, and 1 mg mL⁻¹) to compare their antioxidant activity, effects on four marine fish pathogens (Vibrio harveyi, Vibrio anguillarum, Photobacterium damselae and Tenacibaculum maritimum), cytotoxicity on the PLHC1 tumour cell line, and their impact on immunological parameters in head-kidney leucocytes (HKLs) of gilthead seabream (Sparus aurata). All extracts showed dose-dependent antioxidant activity, while bactericidal effects depended on the solvent and were mainly observed at the highest concentrations. Ethanolic and methanolic extracts displayed clear cytotoxicity, whereas the aqueous extract showed lower toxicity and was selected for further evaluation. In the carrageenan stimulation assay, selected concentrations (0, 0.25, and 0.5 mg mL⁻¹) of the aqueous extract were tested in leucocytes stimulated with λ-carrageenan (0 and 1000 µg mL⁻¹), and respiratory burst and phagocytic activity, cell morphology, and gene expression were analysed. The aqueous extract reduced respiratory burst and phagocytic capacity in activated leucocytes and was associated with morphological signs of cell activation. It also downregulated crel and casp9 expression. These results provide a comparative view of the in vitro bioactivity of different traditional preparations of arnica and show that their biological effects strongly depend on the solvent used and the concentration tested, providing initial experimental information on their cellular effects in fish. Full article

(This article belongs to the Section Physiology and Biochemistry)

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23 pages, 5389 KB

Open AccessArticle

An Edge-Ready Lightweight Computer Vision Framework for On-Site Fish Disease Detection in Aquaculture Management

by Jiawen Li, Weidong Zhang, Shengzhao Xiao, Xuanzhong Chen, Yuesheng Huang, Jujian Lv, Kaihan Lin, Xianglei Hu, Xianxian Zeng and Rongjun Chen

Fishes 2026, 11(5), 280; https://doi.org/10.3390/fishes11050280 - 9 May 2026

Abstract

Efficient detection of fish diseases is essential for intelligent health monitoring and timely intervention in aquaculture. However, current computer vision models remain computationally intensive, hindering their deployment on resource-constrained edge devices in aquaculture applications. To this end, this study developed a lightweight detection [...] Read more.

Efficient detection of fish diseases is essential for intelligent health monitoring and timely intervention in aquaculture. However, current computer vision models remain computationally intensive, hindering their deployment on resource-constrained edge devices in aquaculture applications. To this end, this study developed a lightweight detection framework based on an improved You Only Look Once (YOLO), aiming to achieve a favorable balance between detection accuracy and on-site inference efficiency. First, a Dual-Branch Feature-Preserving Downsampling (DFPD) module was proposed to enhance the extraction of valuable disease-related cues with minimal computational overhead. Subsequently, structured pruning was applied to compress the optimized baseline model. Four pruning techniques, including Slim, GroupTaylor, Layer-Adaptive Magnitude-Based Pruning (LAMP), and L1-based, were evaluated under the same conditions. The enhanced baseline model improved precision from 0.864 to 0.908 and mAP@0.5:0.95 from 0.613 to 0.632, while already reducing the Number of Parameters (Params) and Giga Floating-point Operations Per Second (GFLOPs) compared with the original YOLOv8n. Among the pruning techniques, L1-based produced the best overall trade-off, yielding a final model that maintained a F1-score of 0.860 while reducing Params and GFLOPs by 54.7% and 49.4%, respectively, relative to the original detector. Ablation studies further revealed that a moderate FLOPs reduction of approximately 41% to 47% was optimal for preserving diagnostic performance while enhancing compactness. Edge deployment tests on an RK3588S device verified the framework’s practical inference speed advantage. Therefore, this study offers a deployment-friendly computer vision solution for on-site fish disease detection in aquaculture management, particularly suited to real-world scenarios with limited computational resources. Full article

(This article belongs to the Special Issue Computer Vision Applications for Fisheries and Aquaculture)

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25 pages, 1704 KB

Open AccessArticle

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, Giovanni Sampaio Gonçalves, João Fernando Albers Koch and Luis Otavio Brito

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

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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15 pages, 684 KB

Open AccessArticle

First Feeding of Dwarf Gourami (Trichogaster lalius, Hamilton 1822) Larvae: A Study on Egg Yolk, Rotifer, Infusoria and Spirulina

by İhsan Çelik, Pınar Çelik and Tolga Göksan

Fishes 2026, 11(5), 278; https://doi.org/10.3390/fishes11050278 - 9 May 2026

Abstract

In this study, the effects of different feeds provided during the initial feeding period of Trichogaster lalius (dwarf gourami) larvae on larval survival were evaluated. Larvae reared under laboratory conditions were assigned to four dietary treatments (EY: boiled chicken egg yolk, RO: live [...] Read more.

In this study, the effects of different feeds provided during the initial feeding period of Trichogaster lalius (dwarf gourami) larvae on larval survival were evaluated. Larvae reared under laboratory conditions were assigned to four dietary treatments (EY: boiled chicken egg yolk, RO: live rotifers, IN: infusoria, SP: live Spirulina) during days 3–5 post hatching, after which all groups were enriched with live Artemia on days 5–10. A total of 4800 larvae were distributed across 16 treatment groups. On day 10, larval abundance and total length (mm) were recorded, and survival percentages were subsequently calculated. The pooled survival rates at the end of the experiment were 95.50 ± 4.05 for EY, 95.50 ± 2.53 for RO, 58.58 ± 8.88 for IN, and 77.25 ± 10.23 for SP. Statistical analysis revealed no significant differences in survival between the EY and RO groups (p > 0.05). In contrast, significant differences were observed between the IN group and the SP group, as well as between IN and the remaining treatment groups (p < 0.05). Moreover, no significant differences in total length were detected among the 16 groups at the end of the experiment (p > 0.303). Overall, the findings suggest that, under the present experimental conditions, larval survival of T. lalius was higher in the egg yolk and rotifer feeding treatments than in the infusoria and live Spirulina groups. Full article

(This article belongs to the Section Nutrition and Feeding)

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16 pages, 1214 KB

Open AccessArticle

Feeding Ecology and Trophic Overlap of Sympatric Rajidae Species in the Eastern Ionian Sea (Central Mediterranean)

by Archontia Chatzispyrou, Konstantinos Charalampous, Evgenia Lefkaditou, Aikaterini Anastasopoulou and Constantin Koutsikopoulos

Fishes 2026, 11(5), 277; https://doi.org/10.3390/fishes11050277 - 9 May 2026

Abstract

The feeding ecology of sympatric elasmobranchs provides key insights into trophic interactions and species coexistence within demersal ecosystems. The current study examined the diet composition and trophic relationships of three skate species (Raja asterias, Raja clavata, and Raja miraletus) [...] Read more.

The feeding ecology of sympatric elasmobranchs provides key insights into trophic interactions and species coexistence within demersal ecosystems. The current study examined the diet composition and trophic relationships of three skate species (Raja asterias, Raja clavata, and Raja miraletus) in the eastern Ionian Sea (central Mediterranean). Stomach content analysis was combined with quantitative dietary indices and multivariate statistical approaches, including NMDS, PERMANOVA, SIMPER, and Schoener’s overlap index. All skate species primarily consumed benthic crustaceans and demersal teleost fishes, although differences in prey contribution were detected among species. Raja clavata exhibited higher prey diversity, whereas R. asterias and R. miraletus showed stronger reliance on decapod crustaceans. Multivariate analyses revealed significant interspecific differences in diet composition with generally low-to-moderate trophic overlap among species. These findings suggest that sympatric Rajidae species exploit similar prey resources while maintaining partial trophic partitioning, possibly reducing direct niche overlap and facilitating ecological coexistence. This study contributes to the understanding of trophic structuring in Mediterranean skate assemblages and supports ecosystem-based approaches to demersal fisheries management. Full article

(This article belongs to the Special Issue Trophic Ecology of Freshwater and Marine Fish Species)

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