Fishes

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

Viewed by 1615

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 1443

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 842

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

Viewed by 1008

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

Viewed by 1212

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

Viewed by 1474

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 1073

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 1076

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

Viewed by 1163

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 887

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 1069

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 817

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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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 975

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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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 1203

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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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 928

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 771

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 615

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 846

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 2084

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 814

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 1809

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 1057

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 1643

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

Viewed by 1025

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

Viewed by 940

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 1 | Viewed by 1658

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

Viewed by 2511

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 1010

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 908

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 901

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 2 | Viewed by 1003

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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13 pages, 3270 KB

Open AccessEditor’s ChoiceArticle

Secondary Production and Biomass Dynamics of Mediterranean Brown Trout (Salmo trutta Complex) in Pyrenean Headwater Streams

by Enric Aparicio, Rafel Rocaspana and Carles Alcaraz

Fishes 2025, 10(10), 476; https://doi.org/10.3390/fishes10100476 - 23 Sep 2025

Cited by 3 | Viewed by 873

Abstract

Fish secondary production integrates multiple demographic parameters, including population density, growth, mortality, and recruitment, and thereby provides a comprehensive measure of ecological performance. It is also a valuable tool for assessing the ecological integrity of stream ecosystems and the responses of fish populations [...] Read more.

Fish secondary production integrates multiple demographic parameters, including population density, growth, mortality, and recruitment, and thereby provides a comprehensive measure of ecological performance. It is also a valuable tool for assessing the ecological integrity of stream ecosystems and the responses of fish populations to habitat alteration, climatic variability, and anthropogenic pressures. Despite its relevance, empirical estimates of fish production remain limited due to methodological constraints. In this study, we quantified secondary production and production-to-biomass (P/B) ratios for Mediterranean brown trout (Salmo trutta complex) across six headwater stream reaches in the northeastern Iberian Peninsula, characterized by contrasting hydrological regimes, channel morphology, and water chemistry. Field sampling was conducted over two consecutive annual cycles (2008/2009 and 2009/2010) at all sites, with extended monitoring at two reaches until 2017 to assess long-term variability. Annual trout production, over the two consecutive annual cycles, ranged from 30.9 to 167.8 kg ha⁻¹ year⁻¹ (mean = 82.2 kg ha⁻¹ year⁻¹), and mean P/B ratios ranged from 0.61 to 1.13 (mean = 0.80). These values fall within the intermediate range reported for brown trout globally and reflect the constrained energy dynamics of Mediterranean streams. Higher production was generally associated with strong age-1 recruitment, elevated standing biomass, and greater water alkalinity. Long-term analyses revealed that interannual variation in trout production was significantly correlated with discharge variability, with higher production occurring under more stable flow conditions. However, in addition to flow variability other factors, such as habitat complexity, may modulate local productivity. Consequently, interannual fluctuations at the long-term sites revealed substantial demographic variability influenced by site-specific environmental conditions. These findings offer reference baselines for Mediterranean trout populations and contribute to the ecological basis for their conservation and management. Full article

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

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25 pages, 11592 KB

Open AccessEditor’s ChoiceArticle

Pascua marecoralliensis, a New Species of Goby (Gobiiformes, Gobiidae) from the Central Coral Sea with Validation of the Genus Pascua

by Christopher H. R. Goatley, Andrea I. Varela, Javier Sellanes and Luke Tornabene

Fishes 2025, 10(9), 449; https://doi.org/10.3390/fishes10090449 - 4 Sep 2025

Viewed by 3073

Abstract

In this paper, we use molecular phylogenetics, micro-CT scanning, and morphological analyses to describe a new species of goby, Pascua marecoralliensis, and demonstrate that the genus Pascua is distinct from Hetereleotris, as supported by five diagnostic characters, including modified basicaudal scales [...] Read more.

In this paper, we use molecular phylogenetics, micro-CT scanning, and morphological analyses to describe a new species of goby, Pascua marecoralliensis, and demonstrate that the genus Pascua is distinct from Hetereleotris, as supported by five diagnostic characters, including modified basicaudal scales and reduced sensory papillae patterns. Phylogenetic analysis places Pascua as sister to the Gobiodon group, while Hetereleotris forms a separate clade. The new species, P. marecoralliensis, differs from congeners in fin ray counts, cephalic pore patterns, and head morphology and exhibits unique live colouration. Additionally, we reclassify Hetereleotris readerae and H. sticta as Pascua readerae and P. sticta based on shared genus-specific traits. The distribution of Pascua spans the southern Pacific, suggesting a relict lineage or undiscovered diversity in the genus. This work underscores the importance of integrative taxonomic approaches for resolving cryptic diversity in gobioid fishes and highlights the need for further sampling in understudied regions. Full article

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

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14 pages, 813 KB

Open AccessEditor’s ChoiceArticle

The Influence of Different Feeding Time Management on the Growth and Stress Response of the African Catfish Clarias gariepinuns (Burchel, 1822) Under Farming Conditions

by Marc-C. Hildebrand, David Runge, Björn Bassmann and Harry W. Palm

Fishes 2025, 10(8), 414; https://doi.org/10.3390/fishes10080414 - 18 Aug 2025

Cited by 2 | Viewed by 2518

Abstract

In this study, the growth and welfare of the African catfish (Clarias gariepinus, Burchell 1822) were investigated under industrial farming conditions. For this purpose, the growing success (cm, g) and typical stress related parameters (glucose-, lactate-, cortisol-concentrations, growth hormone, HSI-liver index) [...] Read more.

In this study, the growth and welfare of the African catfish (Clarias gariepinus, Burchell 1822) were investigated under industrial farming conditions. For this purpose, the growing success (cm, g) and typical stress related parameters (glucose-, lactate-, cortisol-concentrations, growth hormone, HSI-liver index) were investigated on the African catfish (102–841 g) in relation to an external stressor (working light and noise) and different feeding regimes (day, night, and day and night feeding) over 83 days. As no significant effects were found among the experimental feeding treatments in relation to the growth performance and investigated stress parameters, the time of feeding seems to have less impact to the production success and stress reactions as suggested before. Regarding our results, the effect of feeding conditioning could have played a strong factor likewise the ageing process of the reared fish species which is known to be rather photophobic. Therefore, the factor of conditioning and its influence to the time shift in feeding regimes and the impact of noise and light stressors during feeding should be investigated separately in future experiments to obtain further results in this context and clarify the validity of the best feeding conditions for African catfish. Full article

(This article belongs to the Special Issue Physiological Response Mechanisms of Aquatic Animals to Stress)

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23 pages, 676 KB

Open AccessFeature PaperEditor’s ChoiceReview

Stunted Versus Normally Growing Fish: Adapted to Different Niches

by Bror Jonsson

Fishes 2025, 10(8), 376; https://doi.org/10.3390/fishes10080376 - 4 Aug 2025

Cited by 2 | Viewed by 3471

Abstract

This literature-based review draws on studies of thirty-four fish species; most are from northern temperate regions. Fish have flexible and indeterminate growth, and often they do not reach their growth and size potential. They may become stunted with impaired growth and early maturity, [...] Read more.

This literature-based review draws on studies of thirty-four fish species; most are from northern temperate regions. Fish have flexible and indeterminate growth, and often they do not reach their growth and size potential. They may become stunted with impaired growth and early maturity, chiefly as a phenotypically plastic reaction. The main causes of stunted growth are negatively density-dependent food availability and keen intraspecific competition leading to environmental stress. Typically, their growth levels off early in life as energy consumptions approach energy costs of maintenance. Females typically attain maturity soon after the energy surplus from feeding starts to decrease. Males are often more variable in size at maturity owing to alternative mating strategies, and their size at maturity depends on both species-specific mating behaviours and environmental opportunities. In polyphenic/polymorphic populations, one phenotype may be stunted and the other phenotype non-stunted; stunted individuals do not perform the required ontogenetic niche shift needed to grow larger. The adult morphology of stunted fish is typically like the morphology of juveniles. Their secondary sexual characters are less pronounced, and they phenotypically retain adaptation to their early feeding niche, which is different from that of large-growing individuals. There are open questions regarding to what extent genetics and epigenetics regulate the life histories of stunted phenotypes. Full article

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

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21 pages, 1379 KB

Open AccessEditor’s ChoiceArticle

Stream Temperature, Density Dependence, Catchment Size, and Physical Habitat: Understanding Salmonid Size Variation Across Small Streams

by Kyle D. Martens and Warren D. Devine

Fishes 2025, 10(8), 368; https://doi.org/10.3390/fishes10080368 - 1 Aug 2025

Viewed by 1641

Abstract

The average body size (fork length) of juvenile salmonids in small streams varies across landscapes and can be influenced by stream temperature, density dependence, catchment size, and physical habitat. In this study, we compared sets of 16 mixed-effects linear models representing these four [...] Read more.

The average body size (fork length) of juvenile salmonids in small streams varies across landscapes and can be influenced by stream temperature, density dependence, catchment size, and physical habitat. In this study, we compared sets of 16 mixed-effects linear models representing these four potentially influencing indicators for three species/age classes to assess the relative importance of their influences on body size. The global model containing all indicators was the most parsimonious model for juvenile coho salmon (Oncorhynchus kisutch; R²m = 0.4581, R²c = 0.5859), age-0 trout (R²m = 0.4117, R²c = 0.5968), and age-1 or older coastal cutthroat trout (O. clarkii; R²m = 0.2407, R²c = 0.5188). Contrary to expectations, salmonid density, catchment size, and physical habitat metrics contributed more to the top models for both coho salmon and age-1 or older cutthroat trout than stream temperature metrics. However, a stream temperature metric, accumulated degree days, had the only significant relationship (positive) of the indicators with body size in age-0 trout (95% CI 1.58 to 23.04). Our analysis identifies complex relationships between salmonid body size and environmental influences, such as the importance of physical habitat such as pool size and boulders. However, management or restoration actions aimed at improving or preventing anticipated declines in physical habitat such as adding instream wood or actions that may lead to increasing pool area have potential to ensure a natural range of salmonid body sizes across watersheds. Full article

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

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27 pages, 1569 KB

Open AccessEditor’s ChoiceReview

Bisphenols: Endocrine Disruptors and Their Impact on Fish: A Review

by Nikola Peskova and Jana Blahova

Fishes 2025, 10(8), 365; https://doi.org/10.3390/fishes10080365 - 29 Jul 2025

Cited by 3 | Viewed by 5431

Abstract

Bisphenols (BPs), particularly bisphenol A (BPA) and its structural analogues, are synthetic compounds widely used in plastics and industrial materials. These substances are also recognised as endocrine-disrupting chemicals (EDCs) due to their ability to interfere with hormonal systems, which has significant implications for [...] Read more.

Bisphenols (BPs), particularly bisphenol A (BPA) and its structural analogues, are synthetic compounds widely used in plastics and industrial materials. These substances are also recognised as endocrine-disrupting chemicals (EDCs) due to their ability to interfere with hormonal systems, which has significant implications for aquatic organisms. This review summarises the occurrence, environmental distribution, and toxicity of BPs in fish, with a focus on estrogenic, androgenic, thyroid, and glucocorticoid disruptions. Studies consistently show that exposure to BPs leads to altered gene expression, developmental abnormalities, impaired reproduction, and disrupted hormonal signalling in various fish species. Although BPA alternatives like bisphenol S, bisphenol F, or bisphenol AF were introduced as safer options, emerging evidence suggests they may pose equal or greater risks. Regulatory measures are evolving, particularly within the European Union, but legislation remains limited for many bisphenol analogues. This review emphasises the need for comprehensive environmental monitoring, stricter regulatory frameworks, and the development of genuinely safer alternatives to minimise the ecological and health impacts of BPs in aquatic systems. Full article

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

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16 pages, 993 KB

Open AccessEditor’s ChoiceReview

The Application of Digital Twin Technology in the Development of Intelligent Aquaculture: Status and Opportunities

by Jianlei Chen, Yong Xu, Hao Li, Xinguo Zhao, Yang Su, Chunhao Qi, Keming Qu and Zhengguo Cui

Fishes 2025, 10(8), 363; https://doi.org/10.3390/fishes10080363 - 25 Jul 2025

Cited by 16 | Viewed by 5578

Abstract

Aquaculture is vital for global food security but faces challenges like disease, water quality control, and resource optimization. Digital twin technology, a real-time virtual replica of physical aquaculture systems, emerges as a transformative solution. By integrating sensors and data analytics, it enables monitoring [...] Read more.

Aquaculture is vital for global food security but faces challenges like disease, water quality control, and resource optimization. Digital twin technology, a real-time virtual replica of physical aquaculture systems, emerges as a transformative solution. By integrating sensors and data analytics, it enables monitoring and optimization of water quality, feed efficiency, fish health, and operations. This review explores the current adoption status of digital twins in aquaculture, highlighting applications in real-time monitoring and system optimization. It addresses key implementation challenges, including data integration and scalability, and identifies emerging opportunities for advancing sustainable, intelligent aquaculture practices. Full article

(This article belongs to the Special Issue Application of Artificial Intelligence in Aquaculture)

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19 pages, 2552 KB

Open AccessEditor’s ChoiceArticle

The Biogeographic Patterns of Two Typical Mesopelagic Fishes in the Cosmonaut Sea Through a Combination of Environmental DNA and a Trawl Survey

by Yehui Wang, Chunlin Liu, Mi Duan, Peilong Ju, Wenchao Zhang, Shuyang Ma, Jianchao Li, Jianfeng He, Wei Shi and Yongjun Tian

Fishes 2025, 10(7), 354; https://doi.org/10.3390/fishes10070354 - 17 Jul 2025

Viewed by 1510

Abstract

Investigating biodiversity in remote and harsh environments, particularly in the Southern Ocean, remains costly and challenging through traditional sampling methods such as trawling. Environmental DNA (eDNA) sampling, which refers to sampling genetic material shed by organisms from environmental samples (e.g., water), provides a [...] Read more.

Investigating biodiversity in remote and harsh environments, particularly in the Southern Ocean, remains costly and challenging through traditional sampling methods such as trawling. Environmental DNA (eDNA) sampling, which refers to sampling genetic material shed by organisms from environmental samples (e.g., water), provides a more cost-effective and sustainable alternative to traditional sampling approaches. To study the biogeographic patterns of two typical mesopelagic fishes, Antarctic lanternfish (Electrona antarctica) and Antarctic deep-sea smelt (Bathylagus antarcticus), in the Cosmonaut Sea in the Indian Ocean sector of the Southern Ocean, we conducted both eDNA and trawling sampling at a total of 86 stations in the Cosmonaut Sea during two cruises in 2021–2022. Two sets of species-specific primers and probes were developed for a quantitative eDNA analysis of two fish species. Both the eDNA and trawl results indicated that the two fish species are widely distributed in the Cosmonaut Sea, with no significant difference in eDNA concentration, biomass, or abundance between stations. Spatially, E. antarctica tended to be distributed in shallow waters, while B. antarcticus tended to be distributed in deep waters. Vertically, E. antarctica was more abundant above 500 m, while B. antarcticus had a wider range of habitat depths. The distribution patterns of both species were affected by nutrients, with E. antarctica additionally affected by chlorophyll, indicating that their distribution is primarily influenced by food resources. Our study provides broader insight into the biogeographic patterns of the two mesopelagic fishes in the remote Cosmonaut Sea, demonstrates the potential of combining eDNA with traditional methods to study biodiversity and ecosystem dynamics in the Southern Ocean and even at high latitudes, and contributes to future ecosystem research and biodiversity conservation in the region. Full article

(This article belongs to the Section Biology and Ecology)

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24 pages, 1937 KB

Open AccessEditor’s ChoiceArticle

Asparagopsis taxiformis Feed Supplementation as a Tool to Improve the Resilience of Farmed Diplodus sargus to Marine Heatwave Events—A Metabolomics Approach

by Marta Dias, Isa Marmelo, Carla António, Ana M. Rodrigues, António Marques, Mário S. Diniz and Ana Luísa Maulvault

Fishes 2025, 10(7), 350; https://doi.org/10.3390/fishes10070350 - 15 Jul 2025

Cited by 2 | Viewed by 2254

Abstract

The need to maximize aquaculture production while addressing environmental and food security challenges posed by climate change has driven research towards the development of functional aquafeeds that enhance performance and immunity in farmed species. However, exposure to dietary and environmental stressors affects marine [...] Read more.

The need to maximize aquaculture production while addressing environmental and food security challenges posed by climate change has driven research towards the development of functional aquafeeds that enhance performance and immunity in farmed species. However, exposure to dietary and environmental stressors affects marine organisms, altering key metabolic pathways best understood through high-throughput “omics” tools. This study assessed the effects of Asparagopsis taxiformis supplementation on central metabolic pathways by analyzing changes in primary metabolite levels in the liver of farmed Diplodus sargus under optimal and suboptimal temperature conditions. Results showed that seaweed supplementation had a beneficial effect on the fish’s primary metabolome; however, inclusion levels and rearing conditions played a crucial role in determining outcomes. While 1.5% supplementation maintained a balanced primary metabolome under optimal temperature conditions, 3.0% supplementation most effectively mitigated the adverse effects of acute thermal stress during a marine heatwave. These findings highlight the nutritive and functional potential of A. taxiformis supplementation in aquafeeds for marine omnivorous fish species and emphasize the importance of evaluating functional aquafeeds under suboptimal rearing conditions. Overall, our results demonstrate the value of metabolomics in elucidating the molecular basis underlying biological pathways in farmed marine fish and optimizing production through climate-smart dietary strategies. Full article

(This article belongs to the Special Issue Advances in Aquaculture Feed Additives)

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55 pages, 3773 KB

Open AccessEditor’s ChoiceReview

Molecular Mechanisms and Biomarker-Based Early-Warning Indicators of Heavy Metal Toxicity in Marine Fish

by Andra Oros, Valentina Coatu, Nicoleta Damir, Diana Danilov, Elena Ristea and Luminita Lazar

Fishes 2025, 10(7), 339; https://doi.org/10.3390/fishes10070339 - 10 Jul 2025

Cited by 25 | Viewed by 6513

Abstract

Heavy metals are among the most persistent and bioaccumulative pollutants in marine ecosystems, posing significant toxicological threats to fish via complex molecular and cellular disruptions. This review synthesizes current knowledge on the cascade of mechanistic responses in marine fish following HM exposure, which [...] Read more.

Heavy metals are among the most persistent and bioaccumulative pollutants in marine ecosystems, posing significant toxicological threats to fish via complex molecular and cellular disruptions. This review synthesizes current knowledge on the cascade of mechanistic responses in marine fish following HM exposure, which includes oxidative stress, modulation of antioxidant responses, activation of detoxification systems, DNA damage, inflammation, apoptosis, neuroendocrine disruption, and ultimately, cellular energy imbalance. In addition to established pathways, the review highlights recent advances in mechanistic understanding and biomarker development, including cellular stress responses, epigenetic regulation, metal homeostasis mechanisms, and novel molecular indicators. These mechanisms support the development of an integrated biomarker framework that combines classical indicators (e.g., antioxidant enzymes, metallothionein) with next-generation endpoints (e.g., miRNA profiles, gene-level responses of metal transporters or stress chaperones, epigenetic alterations). The interpretation of biomarker responses requires consideration of the exposure context, environmental variables, and physiological status to ensure accurate assessment of sublethal toxicity in field settings. By bridging mechanistic understanding with biomonitoring relevance, this review provides a comprehensive foundation for advancing molecular tools in pollution monitoring and risk assessment. Special emphasis is placed on biomarkers specific to heavy metal exposure, enhancing their diagnostic value relative to general stress indicators. Full article

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

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14 pages, 665 KB

Open AccessEditor’s ChoiceArticle

Evaluation of Three Atlantic Salmon Strains for Resistance to Copepodid Sea Lice Attachment

by Michael R. Pietrak, Thomas A. Delomas, Demitri Lifgren and Mark P. Polinski

Fishes 2025, 10(7), 334; https://doi.org/10.3390/fishes10070334 - 8 Jul 2025

Viewed by 1691

Abstract

Sea lice have been a persistent pest of the salmon farming industry for more than 50 years. In this study, we aimed to identify if different strains of Atlantic salmon with discrete long-term lice exposure histories had variable resistance to copepodid attachment and/or [...] Read more.

Sea lice have been a persistent pest of the salmon farming industry for more than 50 years. In this study, we aimed to identify if different strains of Atlantic salmon with discrete long-term lice exposure histories had variable resistance to copepodid attachment and/or different attachment-specific transcriptome patterns. We additionally sought to characterize lice distributions on fins, head, and skin and identify if attachment location influenced transcriptomic profiles of lice. Lice counts were correlated with body size and highest on St. John River (SJR; open ocean-run) relative to Grand Lakes Stream (GLS; 200-year restricted ocean-run) or Sebago Lake (CAS; ~11,000 years landlocked) Atlantic salmon. However, lice density was similar between strains. Skin and fins had expectedly different transcriptomic profiles; however, notable differences were not observed between salmon strains. Variance in lice transcriptomes was minimally affected by attachment location even though lice strongly preferred fins relative to head or body. Attached lice did have different transcriptomic profiles on GLS relative to CAS or SJR. This study cumulatively identified a minimal host evolutionary component for sea lice attachment resistance, although lice behavior post-attachment appeared somewhat affected by strain. Non-uniform settlement distributions and tank-specific variability in lice attachment were observed across populations. Full article

(This article belongs to the Section Fish Pathology and Parasitology)

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15 pages, 1974 KB

Open AccessEditor’s ChoiceArticle

Comparing Year-Class Strength Indices from Longitudinal Analysis of Catch-at-Age Data with Those from Catch-Curve Regression: Application to Lake Huron Lake Trout

by Ji X. He and Charles P. Madenjian

Fishes 2025, 10(7), 332; https://doi.org/10.3390/fishes10070332 - 7 Jul 2025

Cited by 1 | Viewed by 1722

Abstract

Fish year-class strength (YCS) has been estimated via longitudinal analysis of catch-at-age data and via catch-curve regression, but no study has compared the two approaches. The objective of this study was to compare YCS estimates between the two approaches with application to the [...] Read more.

Fish year-class strength (YCS) has been estimated via longitudinal analysis of catch-at-age data and via catch-curve regression, but no study has compared the two approaches. The objective of this study was to compare YCS estimates between the two approaches with application to the lake trout (Salvelinus namaycush) population in the main basin of Lake Huron, one of the Laurentian Great Lakes of North America. YCSs were reconstructed for both hatchery-stocked and wild lake trout. Akaike information criterion (AIC) and Bayesian information criterion (BIC) were used to compare 14 linear mixed-effects models for longitudinal analysis of catch-at-age data, and three linear mixed-effects models for catch-curve regression. From the best models based on AIC or BIC comparisons, YCS estimates with year-class as a fixed effect were consistent with those estimated with year-class as a random effect. Estimated YCS patterns and trends were the same or similar between the longitudinal analysis and the catch-curve regression, indicating that both approaches provide robust estimates of YCS. Potential bias in using the approach of catch-curve regression could be caused by abrupt changes in adult mortality. It is also critical to recognize multiple recruitment origins for using the approach of longitudinal analysis of catch-at-age data. Full article

(This article belongs to the Section Biology and Ecology)

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15 pages, 2654 KB

Open AccessEditor’s ChoiceArticle

Presence and Potential Effect of Microplastics Associated with Anthropic Activity in Two Benthic Fishes Serranus scriba and Lithognathus mormyrus

by Amanda Cohen-Sánchez, Juan Alejandro Sanz, Montserrat Compa, Maria Magdalena Quetglas-Llabrés, Maria del Mar Ribas-Taberner, Lorenzo Gil, Silvia Tejada, Samuel Pinya and Antoni Sureda

Fishes 2025, 10(7), 323; https://doi.org/10.3390/fishes10070323 - 3 Jul 2025

Viewed by 1640

Abstract

Plastic pollution poses a massive problem to the environment, particularly seas and oceans. Microplastics (MPs) ingestion by marine species can generate many adverse effects, including causing oxidative stress. This study evaluated the effects of anthropic activity-related MP presence in two coastal fish species— [...] Read more.

Plastic pollution poses a massive problem to the environment, particularly seas and oceans. Microplastics (MPs) ingestion by marine species can generate many adverse effects, including causing oxidative stress. This study evaluated the effects of anthropic activity-related MP presence in two coastal fish species—Serranus scriba (more related to rocky bottoms) and Lithognathus mormyrus (more related to sandy bottoms)—in two areas of Mallorca Island (Western Mediterranean) with varying anthropic pressures with similar mixed rocky/sandy bottoms. A total of eight fish samples per species and per area (total n = 32), as well as three water samples (500 mL each) and three sediment samples per area, were collected and analyzed. The results showed that despite plastic presence in both areas, the area with higher tourism affluence was also the most polluted. Fourier transform infrared spectroscopy analysis confirmed that the majority of recovered polymers were polyethylene and polypropylene. The pattern of MPs presence was reflected in the biomarker analysis, which showed higher values of antioxidants, namely catalase (CAT) and superoxide dismutase (SOD); detoxification, namely glutathione s-transferase (GST); and inflammation, namely myeloperoxidase (MPO)—enzymes in the gastrointestinal tract of fish from the more polluted area. However, no statistical differences were found for malondialdehyde (MDA) as a marker of lipid peroxidation. As for differences between species, S. scriba presented a higher presence of MPs and measured biomarkers than in L. Mormyrus, suggesting higher exposure. In conclusion, these results showed that increased anthropic activity is associated with a higher presence of MPs which, in turn, induces an adaptative response in exposed fish. Moreover, species living in the same area could be differentially affected by MPs, which is probably associated with different behavioural and feeding habits. Full article

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

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13 pages, 593 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Sardine-Based Diet Mitigates Growth Depression at Low Temperatures in Juvenile Meagre (Argyrosomus regius, Asso 1801)

by Lav Bavčević, Slavica Čolak, Renata Barić, Siniša Petrović and Tin Klanjscek

Fishes 2025, 10(7), 314; https://doi.org/10.3390/fishes10070314 - 2 Jul 2025

Cited by 1 | Viewed by 1546

Abstract

Low seawater temperatures are expected to depress fish growth in aquaculture. However, recent evidence suggests diet composition may offer mitigation for some species. This study evaluated the impact of different diets on juvenile meagre (Argyrosomus regius) in cage farming at low [...] Read more.

Low seawater temperatures are expected to depress fish growth in aquaculture. However, recent evidence suggests diet composition may offer mitigation for some species. This study evaluated the impact of different diets on juvenile meagre (Argyrosomus regius) in cage farming at low seawater temperatures (average 15.19 °C), conditions known to typically suppress meagre growth. Three replicated groups of fish (initial weight ≈ 107 g) were fed for six months either sardines (group A) or commercial pellets (groups B/C, with group C moisturized). The results demonstrate that the nutritional profile of sardines effectively mitigates cold-induced growth reduction in meagre. While pellet-fed meagre experienced expected growth depression, sardine-fed meagre exhibited a doubled temperature growth coefficient (TGC) and an 80% higher final average weight than the pellet groups (A: 346.13 g, B: 194.44 g, C: 188.93 g). Full article

(This article belongs to the Special Issue Advancing Fish Nutrition Research for Sustainable Aquaculture)

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20 pages, 723 KB

Open AccessEditor’s ChoiceArticle

Changes in Subcellular Responses in the Digestive Gland of the Freshwater Mussel Unio crassus from a Historically Contaminated Environment

by Zoran Kiralj, Zrinka Dragun, Jasna Lajtner, Krešimira Trgovčić, Tatjana Mijošek Pavin, Bruno Bušić and Dušica Ivanković

Fishes 2025, 10(7), 317; https://doi.org/10.3390/fishes10070317 - 2 Jul 2025

Cited by 4 | Viewed by 1484

Abstract

Utilizing a multi-biomarker approach, we assessed the potential adverse effects of pollutants on subcellular responses in the digestive gland of the freshwater mussel Unio crassus from a historically contaminated lowland section (KIZ) of the river Mrežnica compared to its less impacted upstream karstic [...] Read more.

Utilizing a multi-biomarker approach, we assessed the potential adverse effects of pollutants on subcellular responses in the digestive gland of the freshwater mussel Unio crassus from a historically contaminated lowland section (KIZ) of the river Mrežnica compared to its less impacted upstream karstic section (REF) and their seasonality (spring vs. autumn). This approach accounted for the diverse modes of action of pollutants by including biomarkers of metal exposure (metallothioneins, MT), general stress (total cytosolic proteins, TP), antioxidative capacity (catalase, CAT; glutathione, GSH; glutathione-S-transferase, GST), oxidative damage (malondialdehyde, MDA), and neurotoxicity (acetylcholinesterase, AChE). Only in spring, MT concentrations were 15% higher at the REF site (4.38 ± 1.06 µg mg proteins⁻¹) compared to the KIZ site (3.69 ± 0.63 µg mg proteins⁻¹), likely related to elevated Cd bioaccumulation due to the karstic substrate. Regardless of the season, mussels from KIZ showed consistently lower TP and GSH, with significantly higher CAT, GST, and MDA levels, indicating elevated stress, activation of antioxidant defenses, and oxidative damage from chronic exposure to pro-oxidant pollutants, including metal(loid)s and organic contaminants (e.g., ibuprofen, nicotine). Compared to the REF site, AChE activity at the KIZ site was higher in late spring and lower in early autumn, indicating seasonal variability in AChE activity at the contamination-impacted location driven by fluctuating exposure to neurotoxicants, such as drugs and insecticides. Overall, biomarker responses indicated that mild historical pollution, reinforced by current low-capacity sources, has an observable impact on mussel health, posing long-term risks to sediment-dwelling aquatic organisms. Full article

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

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19 pages, 3260 KB

Open AccessEditor’s ChoiceArticle

Individual Variation in Movement Behavior of Stream-Resident Mediterranean Brown Trout (Salmo trutta Complex)

by Enric Aparicio, Rafel Rocaspana, Antoni Palau-Ibars, Neus Oromí, Dolors Vinyoles and Carles Alcaraz

Fishes 2025, 10(7), 308; https://doi.org/10.3390/fishes10070308 - 30 Jun 2025

Cited by 4 | Viewed by 1752

Abstract

Understanding individual movement patterns in stream-resident salmonids is critical for conservation and river management, particularly in Mediterranean streams characterized by high environmental variability. We tagged 997 Mediterranean brown trout (Salmo trutta complex) and conducted an 11-month mark–recapture study using Passive Integrated Transponder [...] Read more.

Understanding individual movement patterns in stream-resident salmonids is critical for conservation and river management, particularly in Mediterranean streams characterized by high environmental variability. We tagged 997 Mediterranean brown trout (Salmo trutta complex) and conducted an 11-month mark–recapture study using Passive Integrated Transponder (PIT) technology to assess movement behavior in the Flamisell River (Ebro Basin, northeastern Iberian Peninsula). Movements followed a leptokurtic distribution, with 81.8% of the individuals classified as sedentary (median movement = 24.9 m) and 18.2% as mobile (median movement = 376.2 m). Generalized linear models revealed distinct drivers of fish movement for each group. In sedentary trout, movement was mainly influenced by mesohabitat type, season, sex, and body size, with males and larger individuals moving farther. In mobile trout, mesohabitat type, density, and body size were key predictors. Movement patterns were repeatable over time, indicating consistent behavioral tendencies. These results support a bimodal movement strategy and highlight the importance of individual variation. Conservation planning should account for both sedentary and mobile groups to preserve functional and genetic connectivity and improve resilience of Mediterranean streams. Full article

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

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16 pages, 1657 KB

Open AccessEditor’s ChoiceArticle

Effect of the Inclusion of Natural Pigments on the Performance and Gene Expression of Immune Response and Oxidative Stress of Oreochromis niloticus Cultured in a Biofloc System

by Andres Elias Castro-Castellon, Maria del Carmen Monroy-Dosta, Aida Hamdan-Partida, Martha Patricia Hernandez-Vergara, Jorge Castro-Mejía, German Castro-Mejia, Arnulfo Misael Martinez-Meingüer and José Antonio Mata-Sotres

Fishes 2025, 10(6), 282; https://doi.org/10.3390/fishes10060282 - 8 Jun 2025

Cited by 1 | Viewed by 1823

Abstract

Tilapia (Oreochromis niloticus) is one of the most important species in aquaculture, so the optimization of its culture by using sustainable strategies is fundamental. The aim of this study was to evaluate the effects of incorporating natural pigments (carrot and beetroot [...] Read more.

Tilapia (Oreochromis niloticus) is one of the most important species in aquaculture, so the optimization of its culture by using sustainable strategies is fundamental. The aim of this study was to evaluate the effects of incorporating natural pigments (carrot and beetroot meal) as carbon sources in a biofloc system on the growth, immune response, and oxidative stress of O. niloticus. The experiment comprised four treatments: clear water as control (CT), biofloc with molasses (TBM), biofloc with carrot meal (TBC), and biofloc with beetroot meal (TBB). Results showed that biofloc helped to maintain optimal water quality and high survival rates, but specifically, TBC treatment achieved the highest growth rates and feed conversion ratio, along with elevated leukocyte counts, indicating improved health and immunity. Gene expression analysis revealed enhanced antioxidant activity (sod, gpx) and modulated immune responses (tnf-α, il-1β), particularly under thermal stress. Carrot meal emerged as an effective carbon source in biofloc systems, promoting growth, immune resilience, and oxidative stress resistance in tilapia, while beetroot meal improved pigmentation. These findings highlight the potential of natural pigments to enhance aquaculture sustainability and productivity. Full article

(This article belongs to the Special Issue Fish Hematology)

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14 pages, 4905 KB

Open AccessEditor’s ChoiceArticle

Effects of Micro- and Macroalgae-Supplemented Diets on Growth and Muscle Fibrillar Constitution of Gilthead Seabream, Sparus aurata L., in the Final On-Growing Phase

by María Dolores Ayala, Elena Chaves-Pozo, María Isabel Sáez, Francisco Javier Alarcón, Tomás Francisco Martínez and Marta Arizcun

Fishes 2025, 10(6), 262; https://doi.org/10.3390/fishes10060262 - 2 Jun 2025

Cited by 1 | Viewed by 1822

Abstract

The influence of algae in a final fattening diet for gilthead seabream, Sparus aurata, was studied in an 87 d feeding trial. Five groups were analysed (three tanks per group). In the first 38 days, one lot was fed with standard algae-free [...] Read more.

The influence of algae in a final fattening diet for gilthead seabream, Sparus aurata, was studied in an 87 d feeding trial. Five groups were analysed (three tanks per group). In the first 38 days, one lot was fed with standard algae-free feed (C1) and four batches were fed with an algae-free diet low in fishmeal (FM) and fish oil (FO) and rich in terrestrial vegetables (C2). Subsequently, the C2 diet was changed in three out of the four groups, two of them being fed a diet with a microalgae blend (10%) plus 2% macroalgae (Alaria esculenta), either in raw (C2-R) or hydrolysed (C2-H) form, and a third batch with a diet lacking FM and FO but supplemented with 10% microalgae and 7% algae oil (C2-O) for 49 days. Body length and weight, muscle parameters, and conversion index were analysed after 38 and 87 days. At day 38, no significant differences were observed in any parameter between C1 and C2, but at the end of the trial (day 87), C2 displayed the lowest weight gain and the worst conversion rate, whereas C2-R showed higher body weight, fibrillar hypertrophy, and better conversion rates than the other groups, and C2-H displayed higher hyperplasia values than the other groups. Full article

(This article belongs to the Special Issue Development of Low-Crop, Low-Fishmeal or Low-Fish Oil Feeds for Aquaculture)

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17 pages, 1604 KB

Open AccessEditor’s ChoiceArticle

Stable Isotope Analysis of Two Filter-Feeding Sharks in the Northwestern Pacific Ocean

by Chi-Ju Yu, Shoou-Jeng Joung, Hua-Hsun Hsu, Kwang-Ming Liu and Atsuko Yamaguchi

Fishes 2025, 10(6), 249; https://doi.org/10.3390/fishes10060249 - 26 May 2025

Cited by 2 | Viewed by 3067

Abstract

Understanding the feeding ecology and habitat use of vulnerable shark species is crucial for effective conservation. This study focuses on two large filter-feeding sharks, the megamouth shark (Megachasma pelagios) and whale shark (Rhincodon typus), in Northwestern Pacific waters. Stable [...] Read more.

Understanding the feeding ecology and habitat use of vulnerable shark species is crucial for effective conservation. This study focuses on two large filter-feeding sharks, the megamouth shark (Megachasma pelagios) and whale shark (Rhincodon typus), in Northwestern Pacific waters. Stable isotope analysis (δ¹³C and δ¹⁵N) was conducted on white muscle samples (n = 91) of M. pelagios and fin clips (n = 90) of R. typus, collected via large-mesh drift nets and set nets in Taiwanese waters. In this study, we investigated feeding strategies, ontogenetic dietary shifts, habitat use, and isotopic niche variation in both species. For R. typus, the observed positive correlation between δ¹³C and δ¹⁵N supports the previously proposed active suction filter feeding, as well as implying both a diet with an increasing proportion of higher trophic level prey and an ontogenetic shift. In contrast, M. pelagios displayed a negative correlation, consistent with a previous study associating such patterns with primary or secondary consumers, further aligning with its reported planktonic prey dominance. Both species had increasing δ¹³C with growth, signifying a shift to nutrient-rich habitats. Only R. typus exhibited ontogenetic diet changes (δ¹⁵N). SIBER (Stable Isotope Bayesian Ellipses in R) analysis revealed distinct feeding strategies and habitat use between the two species, potential sexual segregation, and wider isotopic niche widths for males in both species. The findings underscore the importance of considering species-specific behaviors and sex-based differences in conservation strategies. Full article

(This article belongs to the Section Biology and Ecology)

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