Fishes

21 pages, 2046 KB

Open AccessArticle

Population Biology and Reproductive Characteristics of Pseudotolithus elongatus in the Cacine River Estuary, Guinea-Bissau

by Bupebe Júlio Sanca, Diosnes Manuel Nonque, Félix Guillaume, Wilfred Boa Morte Zacarias, Jeremias Francisco Intchama and Gui Manuel Machado Menezes

Fishes 2026, 11(8), 493; https://doi.org/10.3390/fishes11080493 - 21 Aug 2026

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Abstract

Pseudotolithus elongatus is one of the most commercially important species supporting artisanal fisheries in Guinea-Bissau; however, its population biology and reproductive characteristics remain poorly understood, particularly in estuarine ecosystems. This study provides the first integrated biological characterisation of P. elongatus in the Cacine [...] Read more.

Pseudotolithus elongatus is one of the most commercially important species supporting artisanal fisheries in Guinea-Bissau; however, its population biology and reproductive characteristics remain poorly understood, particularly in estuarine ecosystems. This study provides the first integrated biological characterisation of P. elongatus in the Cacine River Estuary, Guinea-Bissau, based on 1776 specimens collected through three independent sampling programmes. Length at first sexual maturity (L₅₀) was estimated using binomial generalised linear models (GLMs); length–weight relationships were assessed by ordinary least squares regression and analysis of covariance (ANCOVA); sexual size dimorphism was evaluated using a battery of parametric and non-parametric tests (ANOVA, Welch’s t-test, Kruskal–Wallis, Kolmogorov–Smirnov); and sex ratio was tested using chi-square goodness-of-fit tests with Yates’ continuity correction. Females attained sexual maturity at a significantly smaller size than males (L₅₀ = 224.9 mm vs. 306.8 mm), and both sexes exhibited positive allometric growth. Females attained larger body sizes and predominated in the largest length classes, confirming pronounced sexual size dimorphism. Reproductive activity occurred throughout the year, with a distinct spawning peak during the dry season (February–April), and the overall sex ratio remained close to parity despite significant variation among length classes and months. These findings provide a biological baseline to support evidence-informed fishery management of P. elongatus in Guinea-Bissau and highlight the need for long-term, standardised monitoring in the Cacine River Estuary. Full article

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

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30 pages, 3205 KB

Open AccessArticle

Distribution of Chondrichthyans in the Greek Seas

by Roxani Naasan Aga-Spyridopoulou, Kyriaki Pyloridou, Martina Ciprian, Ilektra Athinaiou, Stelios Katsanevakis, Dimitrios K. Moutopoulos and Ioannis Giovos

Fishes 2026, 11(8), 492; https://doi.org/10.3390/fishes11080492 - 20 Aug 2026

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Abstract

The Greek seas have hosted a diversity of sharks and rays since antiquity, with Aristotle providing the earliest detailed descriptions in his History of Animals, while the first modern documented record dates back to 1858. Despite this long history of attention and the [...] Read more.

The Greek seas have hosted a diversity of sharks and rays since antiquity, with Aristotle providing the earliest detailed descriptions in his History of Animals, while the first modern documented record dates back to 1858. Despite this long history of attention and the acceleration of research on elasmobranchs over the past two decades, information on their spatial distribution remains fragmented, with most studies focusing on biological and fisheries-related parameters at low taxonomic and/or spatial resolution. This is concerning given that over 50% of Mediterranean chondrichthyans are now threatened with extinction. The present study reconstructs the distribution of extant species in the Greek seas by integrating published literature, mass and social media, biodiversity platforms, citizen science programs, research projects, and national datasets. Although records were compiled from 1858 onwards, only those starting from 1942 contained sufficiently precise locality information to be georeferenced. The review yielded 5596 spatial presence records of initially 67 species; however, after data validation, 62 species were confirmed: 33 shark species, 28 batoid species, and 1 chimaera species, of which 54.8% were from research programs, 30.5% were from published research, and 14.4% were from citizen science and were previously unpublished. These records enrich knowledge of threatened and data-deficient taxa and may serve as a useful baseline for future analyses and distribution modeling, as well as for informing marine spatial planning and conservation prioritization efforts in the eastern Mediterranean. Full article

(This article belongs to the Section Biology and Ecology)

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35 pages, 795 KB

Open AccessReview

Integrating Multi-Omics in Aquaculture: From Genetic Gains to Sustainable Aquaculture

by Chao Guo, Deqi Sun, Ben Yang, Chenyu Shi and Shikai Liu

Fishes 2026, 11(8), 491; https://doi.org/10.3390/fishes11080491 - 20 Aug 2026

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Abstract

In recent years, aquaculture, a critical pillar of global food security, has faced challenges including germplasm resource degradation, frequent disease outbreaks, and insufficient environmental adaptability. To address these issues, omics technologies—centered on genomics, transcriptomics, and related fields—are driving the transformation of aquaculture toward [...] Read more.

In recent years, aquaculture, a critical pillar of global food security, has faced challenges including germplasm resource degradation, frequent disease outbreaks, and insufficient environmental adaptability. To address these issues, omics technologies—centered on genomics, transcriptomics, and related fields—are driving the transformation of aquaculture toward precision and intelligence by establishing a three-dimensional “genotype–phenotype–environment” knowledge network. In this review, we outline foundational applications of omics in aquaculture and highlight the characteristics and current applications of distinct omics approaches. Furthermore, we summarize three core application domains of omics in aquaculture: (1) genetic breeding via genomic selection (GS), gene editing, and multi-omics molecular dissection of economic traits; (2) disease prevention through host–pathogen interaction studies and microbial engineering; and (3) environmental assessment through multi-omics characterization of biological and ecological responses. Additionally, we identify challenges in applying omics technologies to aquatic breeding and database development. Overall, this review aims to provide aquaculture practitioners with actionable insights by enhancing understanding of omics-driven innovations in sustainable aquaculture advancement. Full article

(This article belongs to the Special Issue Aquaculture Omics: Current Status and Future Perspectives)

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18 pages, 7339 KB

Open AccessArticle

Effects of Different Diets on Growth and Immunity in Juvenile Portunus trituberculatus

by Xiaoye Ni, Xuan Zhang, Ping Zhuang, Lei Liu and Rongrong Ma

Fishes 2026, 11(8), 490; https://doi.org/10.3390/fishes11080490 - 20 Aug 2026

Viewed by 257

Abstract

Portunus trituberculatus is an economically important marine crab species in China. Short-term nutritional conditioning during the juvenile stage may improve their physiological readiness before release. This study compared the effects of four dietary treatments on the growth, antioxidant capacity, immune function, and hepatopancreatic [...] Read more.

Portunus trituberculatus is an economically important marine crab species in China. Short-term nutritional conditioning during the juvenile stage may improve their physiological readiness before release. This study compared the effects of four dietary treatments on the growth, antioxidant capacity, immune function, and hepatopancreatic transcriptome of juvenile P. trituberculatus. A 4-week feeding trial compared a commercial pelleted diet (Treatment C) with three natural marine diets: Larimichthys crocea (Treatment Y), Litopenaeus vannamei (Treatment X), and Ruditapes philippinarum (Treatment B). The results demonstrated that Treatments X and B exhibited optimal growth performance, with significantly higher weight gain rate (WGR) and specific growth rate (SGR) than Treatments Y and C (p < 0.05). Regarding immune and antioxidant functions, Treatment X showed significantly enhanced parameters, including total antioxidant capacity (T-AOC) and activities of superoxide dismutase (SOD) and catalase (CAT), as well as contents of reduced glutathione (GSH) and lysozyme (LZM), all of which were markedly higher than those in Treatment C (p < 0.05). Transcriptomic analysis further revealed the molecular mechanisms underlying these physiological enhancements. Compared to the control, Treatment X exhibited significant enrichment in immune-related pathways, specifically the phagosome and gap junction signaling pathways. Notably, key cytoskeleton-related genes (tubulin alpha chain and tubulin beta chain) were significantly up-regulated, suggesting that the shrimp diet enhances cellular immunity by promoting cytoskeletal remodeling and phagocytosis efficiency. In contrast, Treatment B mainly showed enrichment in lysosome and amino sugar metabolism pathways. Full article

(This article belongs to the Special Issue Immunology, Environment, and Nutrition of Aquatic Animals)

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21 pages, 3279 KB

Open AccessArticle

Evaluation of a Modified Codend Configuration for a Marine Mammal Bycatch Reduction Device in a Midwater Trawl Gear

by Jung-Mo Jung, Bong-Jin Cha, Kyu-Suk Choi, Min-Seuk Park, Myounghee Kang and Hyun-Young Kim

Fishes 2026, 11(8), 489; https://doi.org/10.3390/fishes11080489 - 20 Aug 2026

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Abstract

Marine mammal Bycatch Reduction Devices (BRDs) can result in the escape of target fish species. In the present study, a modified single-layer codend configuration developed from previous studies was evaluated using BRDs with guide net angles of 30° and 45°. Catch was collected [...] Read more.

Marine mammal Bycatch Reduction Devices (BRDs) can result in the escape of target fish species. In the present study, a modified single-layer codend configuration developed from previous studies was evaluated using BRDs with guide net angles of 30° and 45°. Catch was collected separately from the codend and the BRD cover to estimate catch loss rates and characteristics. For caught species, catch loss rates based on the number and weight of individuals were 9% and 13% for herring with the 30° guide net and 16% and 18% with the 45° guide net, respectively. For Korean pomfret, catch loss rates were 24% and 23% at 30° and 4% at 45°. These results suggest that further modification of BRD is necessary. In contrast, catch loss rates of mackerel with the 30° guide net reached 56%, whereas hairtail showed loss rates of 60% and 65% with the 45° guide net. Underwater observations indicated that catch loss was influenced by swimming behavior and entanglement with the guide net. Despite the modification of the codend to a single layer, the present study still observed high catch loss rates. However, no bycatch of marine mammals occurred during the experimental operations. Full article

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19 pages, 1778 KB

Open AccessArticle

Aiding Imperiled Fish and Mussel Conservation Using Swimming Performance Metrics to Inform the Design or Modification of Road Stream Crossings

by Allie N. Burdette-Lapuz, Malachi R. Hubbard, Cameron M. Emadi, Preston T. Bean and Edward M. Mager

Fishes 2026, 11(8), 488; https://doi.org/10.3390/fishes11080488 - 19 Aug 2026

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Abstract

Culvert construction at stream crossing sites can lead to zones of high-velocity water flow which can disrupt the dispersal and connectivity of species of greatest conservation need (SGCN) in Texas. To help inform effective culvert design, the swimming performance of the following seven [...] Read more.

Culvert construction at stream crossing sites can lead to zones of high-velocity water flow which can disrupt the dispersal and connectivity of species of greatest conservation need (SGCN) in Texas. To help inform effective culvert design, the swimming performance of the following seven fish species has been measured, the first three of which are SGCN themselves, and the last four serve as hosts for glochidia of SGCN mussels (mussel genera indicated in parentheses): Colorado Roundnose Minnow, Texas Shiner, Headwater Catfish, Largemouth Bass (host for Lampsilis spp.), Green Sunfish (host for Lampsilis spp.), Channel Catfish (host for Cyclonaias spp.) and Blacktail Shiner (host for Fusconaia spp.). The primary objective was to measure the critical swimming speeds (U_crit) under a range of relevant temperatures (15, 22.5, and 30 °C) to be used in site-specific calculations of culvert water velocities (Vf). A secondary objective was to collect additional physiological endpoints of relevance to overall swimming performance, including maximum burst swimming speed (U_max), metabolic rate measurements (i.e., standard (SMR), maximum (MMR) and aerobic scope (AS)) and calculations of cost of transport (COT) and optimal swimming speed (U_opt). As expected, U_crit tended to increase with increasing temperature for several species with metabolic rate measurements following congruent trends, whereas U_max exhibited thermal independence for all species. Full article

(This article belongs to the Section Physiology and Biochemistry)

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28 pages, 8682 KB

Open AccessArticle

Preliminary Sea-Caught Versus Farmed Collection-Source Discrimination of Large Yellow Croaker Using Hyperspectral Features of Anatomical Regions

by Xinyu Ai, Junjie Wu, Shengmao Zhang, Na Lin, Banghong Wei and Quanyou Guo

Fishes 2026, 11(8), 487; https://doi.org/10.3390/fishes11080487 - 19 Aug 2026

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Abstract

Large yellow croaker (Larimichthys crocea) is an economically important marine fish, yet rapid and non-destructive discrimination between sea-caught and farmed collection-source groups remains challenging. This study developed a fish-level analytical workflow integrating YOLO11n-seg instance segmentation with visible–near-infrared hyperspectral imaging to extract [...] Read more.

Large yellow croaker (Larimichthys crocea) is an economically important marine fish, yet rapid and non-destructive discrimination between sea-caught and farmed collection-source groups remains challenging. This study developed a fish-level analytical workflow integrating YOLO11n-seg instance segmentation with visible–near-infrared hyperspectral imaging to extract relative reflectance ratios from six anatomical regions. The analytical cohort comprised 258 unique fish, including 171 sea-caught and 87 farmed individuals. Source categories were assigned according to the original capture or cage-culture collection channels. Fish identity was used as the grouping unit in five-fold internal cross-validation, and classification performance was evaluated based on out-of-fold fish-level predictions. Logistic-regression models achieved AUC values ranging from 0.985 to 1.000 across the six individual anatomical regions. The combined six-region model achieved an accuracy of 0.996 (95% CI, 0.988–1.000) and an AUC of 1.000 (95% CI, 1.000–1.000) within the present cohort. For anatomical-region segmentation, the 20-image validation set contained 140 annotated instances. Bounding-box precision, recall, mAP@0.5, and mAP@0.5–0.95 were 0.976, 0.983, 0.981, and 0.700, respectively, while the corresponding mask metrics were 0.969, 0.976, 0.972, and 0.669. These results indicate that region-specific hyperspectral information can support highly accurate internal discrimination between the two collection-source groups and provide an interpretable basis for characterizing source-associated spectral differences. However, the source labels were not independently verified, potentially influential covariates were incompletely recorded, and no independent external cohort was available. Therefore, the present findings should be interpreted as internally validated collection-source discrimination rather than verified provenance authentication or evidence of external generalizability. Full article

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

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12 pages, 1666 KB

Open AccessArticle

Whole-Genome Resequencing Reveals Genetic Differences and Selection Signatures in Five Neosalanx taihuensis Populations from the Middle and Lower Yangtze River

by Yuting Ding, Xizhao Zhang, Yanfeng Zhou, Dian Fang, Jia Yuan and Yang You

Fishes 2026, 11(8), 486; https://doi.org/10.3390/fishes11080486 - 19 Aug 2026

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Abstract

Neosalanx taihuensis is a fish species endemic to China, primarily distributed in the middle and lower reaches of the Yangtze and Huaihe rivers and their affiliated lakes. To assess its resource status and facilitate targeted conservation of genetic diversity, we analyzed genetic differences [...] Read more.

Neosalanx taihuensis is a fish species endemic to China, primarily distributed in the middle and lower reaches of the Yangtze and Huaihe rivers and their affiliated lakes. To assess its resource status and facilitate targeted conservation of genetic diversity, we analyzed genetic differences among populations in the lower Yangtze River. Samples were collected from four natural river populations (JJ, AQ, NJ, and TZ) and one lacustrine population (THL). Whole genome resequencing was performed to characterize genetic diversity, population structure, and selection signatures across the five populations. The results showed no obvious genetic divergence among the natural river populations, whereas all natural river populations were distinctly separated from the THL population. The natural river populations harbored higher genetic diversity than the THL population. Gene flow analysis suggested that historical gene exchange might have occurred between TZ and THL, as well as between TZ and NJ. Selective sweep analysis identified Chr01, Chr04, Chr09, and Chr15 as candidate genomic regions potentially carrying adaptive selection signatures. In summary, conservation efforts should prioritize the genetic diversity of both natural river populations and the THL population, facilitate gene flow among populations, and adopt differentiated management strategies for each group. Full article

(This article belongs to the Section Biology and Ecology)

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22 pages, 3205 KB

Open AccessArticle

The Study on the Biological Characteristics of Photobacterium damselae subsp. damselae Affected by the Deletion of the Iron Uptake System Genes tonB1 and tonB2

by Hua Jiang, Yufei Ji, Zhiqi Zhang, Yongxiang Yu, Chunyuan Wang, Yingeng Wang, Xiaojun Rong, Aijun Ma, Shuyi Li and Zheng Zhang

Fishes 2026, 11(8), 485; https://doi.org/10.3390/fishes11080485 - 19 Aug 2026

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Abstract

Photobacterium damselae subsp. damselae (PDD), a marine fish pathogen, has an unclear contribution of tonB genes to iron acquisition and pathogenicity. ΔtonB1-PDD and ΔtonB2-PDD mutants as well as their complemented strains were generated via homologous recombination from the virulent [...] Read more.

Photobacterium damselae subsp. damselae (PDD), a marine fish pathogen, has an unclear contribution of tonB genes to iron acquisition and pathogenicity. ΔtonB1-PDD and ΔtonB2-PDD mutants as well as their complemented strains were generated via homologous recombination from the virulent strain PDD1605. Growth was evaluated by monitoring OD₆₀₀ with viable-count calibration, intracellular iron was measured using a colorimetric assay, biofilm was detected by crystal violet staining, transcription was analyzed through qRT-PCR, and pathogenicity was assessed via an 8-day intramuscular challenge in black rockfish (Sebastes schlegelii). Under iron limitation induced by 100 μM 2,2′-dipyridyl, the maximum density decreased from 4.51 × 10⁸ CFU/mL in wild-type (WT-PDD) to 4.00 × 10⁸ and 3.64 × 10⁸ CFU/mL in ΔtonB1-PDD and ΔtonB2-PDD respectively, and was largely restored after complementation. The intracellular iron content declined from 3.75 × 10⁻⁴ ± 4.00 × 10⁻⁶ nmol/10⁶ cells in WT-PDD to 3.13 × 10⁻⁴ ± 1.05 × 10⁻⁵ nmol/10⁶ cells in ΔtonB1-PDD and 2.55 × 10⁻⁴ ± 2.00 × 10⁻⁵ nmol/10⁶ cells in ΔtonB2-PDD. Compared with WT-PDD, biofilm formation was reduced by 22.1% in ΔtonB1-PDD and by 24.8% in ΔtonB2-PDD. Deletion of tonB2 induced mild yet statistically significant transcriptional alterations in multiple iron acquisition and virulence-related genes, while colony morphology, swarming motility, hemolysis, phospholipase activity, biochemical traits, and antimicrobial susceptibility remained unchanged. In the high-dose challenge assay, WT-PDD caused 100% mortality within 2 days, whereas ΔtonB1-PDD and ΔtonB2-PDD caused 17/20 and 18/20 deaths respectively; all infected groups reached 100% mortality by day 3. In the low-dose challenge assay, WT-PDD, ΔtonB1-PDD, and ΔtonB2-PDD caused 12/20, 12/20, and 13/20 deaths by day 2, with cumulative mortalities reaching 80%, 70%, and 80% by day 8, respectively. Kaplan–Meier analysis detected no significant differences among the survival curves at either challenge dose. These findings suggest that tonB1 and tonB2 play roles in iron acquisition, low-iron adaptation, and biofilm formation, with tonB2 deletion exerting greater effects on growth and intracellular iron accumulation under iron-limited conditions. Full article

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

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19 pages, 5882 KB

Open AccessArticle

Environmental DNA Metabarcoding Reveals the Variations in Fish Diversity Across the Yangtze River Basin and the Effects of the Three Gorges Dam

by Wei Chen, Chunfang Wang, Shiyun Chi, Guangbin Gao, Zhongguan Jiang, Yang Wang, Zhe Leng, Mi Wei, Xianfu Zhao and Peiming Ma

Fishes 2026, 11(8), 484; https://doi.org/10.3390/fishes11080484 - 18 Aug 2026

Viewed by 444

Abstract

It is imperative that freshwater fish biodiversity research incorporates diverse components, encompassing taxonomy, phylogeny and function, alongside multifaceted facets, including richness, divergence and regularity. This comprehensive approach is essential to facilitate a more profound comprehension of freshwater ecosystem functions, to elucidate the mechanisms [...] Read more.

It is imperative that freshwater fish biodiversity research incorporates diverse components, encompassing taxonomy, phylogeny and function, alongside multifaceted facets, including richness, divergence and regularity. This comprehensive approach is essential to facilitate a more profound comprehension of freshwater ecosystem functions, to elucidate the mechanisms underpinning fish community assembly, and to accurately assess the impacts of anthropogenic disturbance. Consequently, this scientific understanding can inform the development of effective fish conservation and ecosystem management strategies. This study utilized environmental DNA metabarcoding to assess the diversity of fish across the entire Yangtze River, encompassing the upper reach (Upper), the Three Gorges Reservoir area (RES_SX), and the downstream reach (Down). The results indicated that 150 distinct fish species were detected, with the RES_SX area exhibiting a significantly lower taxonomic diversity and fish detection rate in comparison to the other two regions. Conversely, phylogenetic and functional diversity exhibited stability post-normalization by taxonomic richness. Furthermore, investigation of the divergence facet of alpha-diversity demonstrated a reduction in clustering and an improvement of overdispersion on the phylogenetic and functional diversity, respectively, in the RES_SX and Down regions. Beta-diversity analysis further revealed lower taxonomic beta-diversity but higher phylogenetic and functional beta-diversity in the RES_SX area. A substantial degree of geographic distance-dependent similarity was identified for all three components of beta-diversity in the Upper Reach. Conversely, these components were found to be disrupted in the Down Reach. Finally, an analysis of the assembly mechanism revealed stochastic processes, dispersal limitation and drift as the dominant factors shaping the fish communities, with reduced dispersal limitation in the RES_SX area. This study provides novel insights into the multidimensional diversity of fish populations in response to dam construction, emphasizing the necessity of integrating multiple facets of diversity for accurate impact assessment and supporting evidence-based conservation of fish species in the Yangtze River. Full article

(This article belongs to the Section Biology and Ecology)

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20 pages, 2605 KB

Open AccessArticle

Challenges for Sustainable Coastal Fisheries in a Changing Marine Environment: Spatiotemporal Impacts of Offshore Wind Farm Development in Taiwan

by Yan-Lun Wu, Po-Yuan Hsiao, Yonatan Isai Valladares Ponce, Sunardi Sunardi, Aloysius Dimas Sanjaya Saliyo, Li-Xiang Li and Kuo-Wei Lan

Fishes 2026, 11(8), 483; https://doi.org/10.3390/fishes11080483 - 18 Aug 2026

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Abstract

Offshore wind farm (OWF) development raises concerns regarding potential conflicts with local fisheries and marine ecosystems. This study investigated the spatiotemporal dynamics of gillnet and trawl fisheries in the coastal waters off Changhua, Taiwan, across various development phases. (2016–2024). Spatial analysis revealed distinct [...] Read more.

Offshore wind farm (OWF) development raises concerns regarding potential conflicts with local fisheries and marine ecosystems. This study investigated the spatiotemporal dynamics of gillnet and trawl fisheries in the coastal waters off Changhua, Taiwan, across various development phases. (2016–2024). Spatial analysis revealed distinct operational patterns: gillnet fleets operated within and adjacent to wind farms, while trawl activities were concentrated in northern offshore waters, largely avoiding the development zone. The gillnet fishery demonstrated a significant increase in Income Per Unit Effort (IPUE), suggesting that local fishers successfully employed adaptive strategies. The IPUE of the trawl fishery indicated a slightly lower value during this period. These findings indicate that current OWF development has historically coexisted with gillnet fisheries without causing economic loss. The catch composition of gillnet fisheries remained stable, dominated by Silver croaker and Pharaoh cuttlefish. The species diversity indices of both fisheries showed a stable to increasing trend driven by seasonal variability rather than construction impacts. The habitat-driven shift in community structure was observed within the wind farm zone (gillnet fisheries), where the dominance of benthic species (e.g., Flatfish) transitioned toward reef-associated taxa (e.g., Spotted catfish, Black Sea bream). This indicates that the turbine foundations may function as artificial reefs, supporting a more complex assemblage. Nevertheless, the observed habitat alterations highlight the necessity for long-term monitoring to ensure the sustainable symbiosis of renewable energy expansion and marine resource conservation. Full article

(This article belongs to the Section Fishery Economics, Policy, and Management)

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22 pages, 2670 KB

Open AccessArticle

Regulatory Effects of Graded Dietary Aqueous Chlorella Extract on Intestinal Histomorphology, Microbial Homeostasis, Immune and Antioxidant Functions in Litopenaeus vannamei

by Anqi Pang, Wen Yan, Xuying Jia, Dan Zhang, Peng Shao and Wenli Zhou

Fishes 2026, 11(8), 482; https://doi.org/10.3390/fishes11080482 - 18 Aug 2026

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Abstract

Aqueous Chlorella extract (CE) is a functional feed additive derived from widely cultivated microalgae. It is rich in proteins, polysaccharides, pigments, polyunsaturated fatty acids, vitamins and other bioactive compounds. CE possesses great potential to improve the health status and physiological performance of aquatic [...] Read more.

Aqueous Chlorella extract (CE) is a functional feed additive derived from widely cultivated microalgae. It is rich in proteins, polysaccharides, pigments, polyunsaturated fatty acids, vitamins and other bioactive compounds. CE possesses great potential to improve the health status and physiological performance of aquatic animals. This study investigated the effects of dietary CE on inflammatory response, non-specific immunity, antioxidant capacity, lipid metabolism, immune gene expression, intestinal histomorphology and intestinal microbiota in Litopenaeus vannamei. Shrimp were fed diets containing 0%, 1%, or 5% CE for 60 days. The 1% CE treatment produced stronger responses in several non-specific immune and antioxidant-related indicators and induced broader changes in immune-related gene expression. In contrast, the 5% CE treatment showed more pronounced changes in inflammation-related factors, lipid metabolism, and intestinal morphology. CE supplementation also altered intestinal microbial composition and predicted microbial functions, with different response patterns between the two inclusion levels. A distinctive feature of this study is the integrated identification of inclusion-level-specific response patterns across host physiological and intestinal microbial endpoints, rather than a simple increase in effects with increasing CE inclusion. Overall, the 1% treatment was more closely associated with immune and antioxidant-related responses, whereas the 5% treatment was more closely associated with anti-inflammatory, lipid-regulatory, and intestinal effects. These findings demonstrate the potential of CE as a functional aquafeed additive for improving aquatic animal health and provide a scientific basis for its application in sustainable shrimp aquaculture. Full article

(This article belongs to the Special Issue Advances in the Application of Microalgae in Aquaculture)

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17 pages, 62809 KB

Open AccessArticle

Effects of Different Farming Models on Muscle Nutrients, Muscle Transcriptome and Intestinal Microbiota in Pelodiscus sinensis

by Fuyong Huang, Kefan Guo, Xiao Liang, Lun Qian, Jinyu Tang, Qinghua Jiang, Lina Jiang, Jubin Xing, Yu Zhang and Qingman Yang

Fishes 2026, 11(8), 481; https://doi.org/10.3390/fishes11080481 - 18 Aug 2026

Viewed by 195

Abstract

Farming models profoundly influence the biological traits of aquatic organisms. This study compared muscle nutrients, muscle transcriptome, and gut microbiota of Pelodiscus sinensis reared under rice-field and pond conditions. Compared with the pond group (Group P), the rice-field group (Group R) exhibited significantly [...] Read more.

Farming models profoundly influence the biological traits of aquatic organisms. This study compared muscle nutrients, muscle transcriptome, and gut microbiota of Pelodiscus sinensis reared under rice-field and pond conditions. Compared with the pond group (Group P), the rice-field group (Group R) exhibited significantly lower linoleic acid (LA) and higher arachidonic acid (ARA), indicating an altered muscle fatty acid profile. Transcriptomic analysis further showed that differentially expressed genes were mainly involved in fatty acid metabolic processes. For gut microbiota, Group R had a higher relative abundance of Firmicutes_C at the phylum level, and Acidaminococcus was uniquely detected at the genus level. These findings reveal that rice-field culture drives distinct muscle fatty acid profiles and gut microbial characteristics in P. sinensis, providing a theoretical basis for understanding the effects of rice-field culture on turtle nutrition and intestinal health. Full article

(This article belongs to the Section Nutrition and Feeding)

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13 pages, 6819 KB

Open AccessArticle

Novel Hepatopancreas-Predominant C-Type Lectin (LvCTL) Contributes to Resistance Against Vibrio parahaemolyticus in Shrimp Litopenaeus vannamei

by Ning Fu, Mengxin Xing, Yuyu Wang, Linwei Yang, Di Wang, Taolin Fan, Bang Xiao and Shengwen Niu

Fishes 2026, 11(8), 480; https://doi.org/10.3390/fishes11080480 - 18 Aug 2026

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Abstract

C-type lectins (CTLs) are important pattern recognition receptors (PRRs) involved in innate immune defense in crustaceans. In this study, a novel C-type lectin, designated LvCTL, was identified and functionally characterized from Litopenaeus vannamei. Sequence analysis revealed that the open reading frame (ORF) [...] Read more.

C-type lectins (CTLs) are important pattern recognition receptors (PRRs) involved in innate immune defense in crustaceans. In this study, a novel C-type lectin, designated LvCTL, was identified and functionally characterized from Litopenaeus vannamei. Sequence analysis revealed that the open reading frame (ORF) of LvCTL is 495 bp in length and encodes a 164-amino acid polypeptide containing a typical C-type lectin-like domain but lacking the classical carbohydrate-binding motifs. Notably, two novel EPF motifs were identified in the CTLD region, suggesting a potential non-canonical ligand recognition pattern. Phylogenetic analysis revealed that LvCTL clustered with other crustacean CTLs. Tissue expression analysis revealed that LvCTL exhibited the highest transcript level in the hepatopancreas. After immune stimulation, LvCTL expression in the hepatopancreas was significantly regulated by LPS, Vibrio parahaemolyticus, Staphylococcus aureus, WSSV and Poly(I: C), indicating its involvement in antimicrobial immune responses. RNA interference assays showed that knockdown of LvCTL significantly increased the bacterial burden and reduced the survival rate of shrimp after V. parahaemolyticus infection. Furthermore, recombinant LvCTL displayed broad bacterial binding activity to Gram-negative and Gram-positive bacteria and induced calcium-dependent agglutination of V. parahaemolyticus and S. aureus. Taken together, these results demonstrate that LvCTL functions as an important immune recognition molecule and contributes to antibacterial defense against V. parahaemolyticus in L. vannamei. These findings broaden our understanding of the functional diversity of shrimp CTLs and their contributions to crustacean innate immunity. Full article

(This article belongs to the Topic Immunology and Disease Prevention and Control in Aquatic Animals)

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30 pages, 38707 KB

Open AccessArticle

Peak-at-Intermediate-Salinity Transcriptional and Histological Responses of Triploid Rainbow Trout Gills to Salinity Gradients

by Yanming Sui, Jingtao Liu, Haopeng Hu, Yan Ji, Yuanhao Ren, Bo Qin, Na Ying, Tingting Lin, Siping Li, Hanfeng Zheng and Lei Li

Fishes 2026, 11(8), 479; https://doi.org/10.3390/fishes11080479 - 15 Aug 2026

Viewed by 231

Abstract

Using a three-factor orthogonal design, we investigated the transcriptomic and histological responses of triploid rainbow trout (Oncorhynchus mykiss) gills across three salinities (10, 20, and 30 ppt) over 60 days, with temperature and body size as background conditions. Results showed that [...] Read more.

Using a three-factor orthogonal design, we investigated the transcriptomic and histological responses of triploid rainbow trout (Oncorhynchus mykiss) gills across three salinities (10, 20, and 30 ppt) over 60 days, with temperature and body size as background conditions. Results showed that 20 ppt was associated with extensive transcriptional reprogramming, with 3333 differentially expressed transcripts (DETs), whereas 30 ppt induced only 120 DETs; WGCNA further identified salinity-correlated modules involved in ion transport and ribosome biogenesis. Histological alterations remained within physiological ranges with no salinity-dependent severity gradient, as confirmed by semi-quantitative scoring. These findings demonstrate that triploid rainbow trout gills employ distinct molecular strategies at medium versus high salinity. Within the 10–30 ppt range examined, 20 ppt was the salinity at which transcriptional reprogramming was most active, suggesting that this intermediate salinity warrants further investigation as a potential acclimation stage. Full article

(This article belongs to the Section Physiology and Biochemistry)

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25 pages, 3119 KB

Open AccessReview

Oncorhynchus mykiss as a Salmonid Functional Genomics Model: A Structured Narrative Review of Genomic Resources, Mucosal Immunity, Disease Resistance, Environmental Stress, and Causal Validation

by Zhongquan Jiang, Sijia Wu, Yong Zheng, Di Peng, Siping Li, Yuanhao Ren, Bo Qin, Hanfeng Zheng, Lei Li and Tingting Lin

Fishes 2026, 11(8), 478; https://doi.org/10.3390/fishes11080478 - 15 Aug 2026

Viewed by 263

Abstract

Rainbow trout (Oncorhynchus mykiss) is an important cold-water aquaculture species and a tractable salmonid model for functional genomics. Rapid advances in chromosome-level genome assemblies, genetic variation resources, regulatory annotations, tissue and cell models, controlled challenge systems, and genome-editing technologies have established [...] Read more.

Rainbow trout (Oncorhynchus mykiss) is an important cold-water aquaculture species and a tractable salmonid model for functional genomics. Rapid advances in chromosome-level genome assemblies, genetic variation resources, regulatory annotations, tissue and cell models, controlled challenge systems, and genome-editing technologies have established an increasingly integrated framework for linking genomic variation with measurable phenotypes. Evidence from studies of mucosal immunity, disease-resistance genetics, and environmental stress responses indicates that these resources can improve candidate-gene prioritization and mechanistic interpretation across molecular, cellular, tissue, and whole-fish levels. However, differential gene expression, quantitative trait locus and genome-wide association signals, genomic predictions, and cell-type localization remain largely associative and rarely provide direct evidence of causality. Interpretation is further complicated by salmonid-specific whole-genome duplication, because retained paralogues may exhibit tissue-specific divergence, functional redundancy, and compensatory responses. Further progress will require the integration of pangenomics, regulatory annotation, single-cell and spatial analyses, and paralogue-aware functional perturbation in both cell-based and whole-fish systems. Such integration will strengthen causal inference, clarify genotype–phenotype relationships, and support disease-resistant breeding, healthy aquaculture, and environmental risk assessment. Full article

(This article belongs to the Section Genetics and Biotechnology)

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22 pages, 8412 KB

Open AccessArticle

Effects of Copper Nanoparticle Exposure on Physiological Status and Histological Structure of Yellowtail Kingfish (Seriola aureovittata)

by Yan Jiang, Zhixin Jin, Yongjiang Xu, Aijun Cui, Jichang Zheng, Xin Cai and Zhiyong Xue

Fishes 2026, 11(8), 477; https://doi.org/10.3390/fishes11080477 - 14 Aug 2026

Viewed by 299

Abstract

Copper nanoparticles (Cu-NPs) are widely used in aquaculture for their growth-promoting and immunoenhancing properties. However, excessive or over-accumulated Cu-NPs in aquaculture water cause toxicity through waterborne immersion. To explore the toxicity effects of waterborne Cu-NPs on yellowtail kingfish (Seriola aureovittata), a [...] Read more.

Copper nanoparticles (Cu-NPs) are widely used in aquaculture for their growth-promoting and immunoenhancing properties. However, excessive or over-accumulated Cu-NPs in aquaculture water cause toxicity through waterborne immersion. To explore the toxicity effects of waterborne Cu-NPs on yellowtail kingfish (Seriola aureovittata), a 7-day exposure experiment comprising a control group (no Cu-NPs), a low-concentration group (0.120 mg/L), and a high-concentration group (0.384 mg/L) was conducted, followed by a 7-day recovery period without Cu-NP stress. Exposure to Cu-NPs significantly elevated antioxidant enzyme activities (GSH-Px, Cu/Zn-SOD) and thiobarbituric acid reactive substances (TBARS) level in liver and posterior kidney, indicating significant oxidative stress. In the liver, levels of epinephrine and diacylglycerol were significantly upregulated, the cAMP signaling pathway was disrupted, and the NF-κB signaling pathway was activated, along with the downregulation of ap-1 and erk1-2 and upregulation of gadd45β, reducing cell proliferation and viability. These alterations resulted in hepatocellular vacuolation and blurred outlines of hepatic lobules. In the gill, high-concentration Cu-NPs activated oxidative phosphorylation, phagosome, and cell-adhesion molecules pathways and downregulated genes related to cell proliferation, adhesion, and tight junctions (i.e., l1cam, camd1, cntn1, cdh2, and nectin1), leading to cellular vacuolization and epithelial separation in histology. These changes disrupted osmotic balance and significantly upregulated Na⁺/K⁺-ATPase activity. All histological damages were not fully recovered within the tested recovery period. Therefore, under conditions of continuous exposure, the concentration of Cu-NPs used for juvenile yellowtail kingfish in aquaculture should be kept below 0.120 mg/L, with a recovery period exceeding 7 days. These results reveal the toxicity mechanisms of Cu-NPs and provide a scientific basis for establishing safe application guidelines in yellowtail kingfish aquaculture. Full article

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

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10 pages, 9766 KB

Open AccessCommunication

First Detection and Seasonal Dynamics of Proliferative Kidney Disease in Northwestern Italy

by Annalisa Cotugno, Paolo Pastorino, Lucio Fariano, Sara Glorio Patrucco, Fabio Bondavalli, Giorgia Zicarelli, Giulia Milanese, Martina Alessandra Gini, Giuseppe Esposito, Cinzia Bergamino, Pier Luigi Acutis, Elena Bozzetta, Marino Prearo and Silvia Colussi

Fishes 2026, 11(8), 476; https://doi.org/10.3390/fishes11080476 - 14 Aug 2026

Viewed by 241

Abstract

Proliferative kidney disease (PKD), caused by the myxozoan parasite Tetracapsuloides bryosalmonae, represents a major threat to salmonid populations and aquaculture, particularly under warming environmental conditions. In Italy, its distribution remains poorly documented. This study aimed to update the epidemiological status of PKD [...] Read more.

Proliferative kidney disease (PKD), caused by the myxozoan parasite Tetracapsuloides bryosalmonae, represents a major threat to salmonid populations and aquaculture, particularly under warming environmental conditions. In Italy, its distribution remains poorly documented. This study aimed to update the epidemiological status of PKD by investigating its occurrence in a trout farm (Piedmont, northwestern Italy), a previously unreported area. A total of 787 individuals of Oncorhynchus mykiss were sampled between May and October 2024 across three seasonal periods. Fish were examined using necropsy, bacteriological, and molecular analyses. Water temperature ranged from 12.4 to 20.3 °C, showing a clear seasonal trend. Overall PKD prevalence was 42.3%, with significant temporal variation, increasing from 23.0% in early summer to 73.0% in late summer, and declining to 3.9% in autumn. A multivariable logistic regression model showed that PKD-positive fish had a lower probability of presenting macroscopic lesions, while sampling period was the main predictor of infection. These results revealed a temporal mismatch between pathological and molecular findings, highlighting the need for further histopathological validation of the observed seasonal patterns. This study provides the first evidence of PKD in southwestern Piedmont, extending the currently documented distribution of the disease in Italy and highlighting the need for enhanced surveillance under climate change. Full article

(This article belongs to the Special Issue Parasites in Aquaculture)

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12 pages, 1874 KB

Open AccessArticle

Molecular Characterization, Gene Expression and Antibacterial Activity Analysis of a Novel Piscidin (Piscidin-4) of Largemouth Bass (Micropterus Salmoides)

by Jingyun Tian, Liqiang Zhang, Qihuan Zhang, Yang Xu, Xuan Wei, Mingzhu Pan, Zisheng Wang and Zhitao Qi

Fishes 2026, 11(8), 475; https://doi.org/10.3390/fishes11080475 - 14 Aug 2026

Viewed by 211

Abstract

Piscidins, fish-specific antimicrobial peptides (AMPs), play important roles in the innate immunity of fish against invading bacteria. In this study, a novel piscidin was identified in largemouth bass (Micropterus salmoides) (MSPiscidin-4), which contained an active peptide of 25 aa with an [...] Read more.

Piscidins, fish-specific antimicrobial peptides (AMPs), play important roles in the innate immunity of fish against invading bacteria. In this study, a novel piscidin was identified in largemouth bass (Micropterus salmoides) (MSPiscidin-4), which contained an active peptide of 25 aa with an amphipathic helix possessing distinct hydrophobic and positively charged regions. MSPiscidin-4 belongs to the Group I piscidins as determined by sequence identity, homology modeling and phylogenetic tree analysis. MSPiscidin-4 was constitutively expressed in all seven selected tissues, with the highest transcript level in the gill and the lowest in the brain and spleen. Furthermore, MSPiscidin-4 was significantly up-regulated in spleen from 6 h to 24 h post-lipopolysaccharide (LPS) stimulation. A synthetic MSPiscidin-4 peptide was produced by the Fmoc solid-phase synthesis method and exhibited antibacterial activity against several aquatic bacterial strains, with the strongest against Aeromonas hydrophila, followed by Vibrio splendidus, Staphylococcus aureus, Edwardsiella tarda, and the weakest against E. coli and A. veronii. MSPiscidin-4 is the fourth piscidin reported in largemouth bass, showing distinct sequence identity (35.0–68.0% with previously reported MSPiscidins), physicochemical properties (net charge +5, pI 12.48), tissue distribution (highest expression in gill), and antibacterial potency (particularly strong against A. hydrophila). Our results enrich the piscidin components and deepen the understanding of piscidins against invading bacteria in largemouth bass. Full article

(This article belongs to the Section Welfare, Health and Disease)

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15 pages, 2416 KB

Open AccessSystematic Review

Global Disparities in the Recreational Fishery Economy: A Systematic Review

by Wenhao Sha, Guiying Chen, Bo Han, Xinjun Chen and Qilei Zhao

Fishes 2026, 11(8), 474; https://doi.org/10.3390/fishes11080474 - 13 Aug 2026

Viewed by 277

Abstract

Recreational fisheries contribute significantly to global economies through tourism, employment, and ecosystem service valorization. However, a systematic understanding of their economic magnitude and regional disparities remains fragmented. This study conducts a systematic review of 112 peer-reviewed articles published between 1991 and 2024, synthesizing [...] Read more.

Recreational fisheries contribute significantly to global economies through tourism, employment, and ecosystem service valorization. However, a systematic understanding of their economic magnitude and regional disparities remains fragmented. This study conducts a systematic review of 112 peer-reviewed articles published between 1991 and 2024, synthesizing the economic evidence across three key domains: consumer behavior, resource management, and ecological interactions. Consistent with previous research, our systematic synthesis documents a pronounced imbalance in the existing evidence base: studies from high-income countries more frequently report established management frameworks (e.g., bag limits, catch-per-unit-effort monitoring) and robust economic valuation mechanisms (e.g., Willingness to Pay estimation), whereas low- and middle-income countries face significant barriers in infrastructure and resource quantification. We identify that non-market valuation methods, particularly the travel cost method and consumer surplus analysis, are critical for internalizing the environmental value of fisheries. Furthermore, while ecological restoration demonstrates clear positive feedback loops for local economies, the sector exhibits high vulnerability to external shocks, such as the COVID-19 pandemic. This review highlights the urgent need to bridge the data gap in developing regions and suggests that transferring successful adaptive management models from developed nations is essential for achieving equitable and sustainable growth in the global recreational fishery economy. Full article

(This article belongs to the Section Fishery Economics, Policy, and Management)

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17 pages, 8342 KB

Open AccessArticle

Probiotics Alleviate Nonylphenol-Induced Hepatotoxicity in Silurus meridionalis via Reprogramming Arachidonic Acid Metabolism and Suppressing Ferroptosis: A Preliminary Study

by Deqin Luo, Fanglian Lu, Lian Yang, Zhenbo Gan, Xianbo Zhang and Ranran Dong

Fishes 2026, 11(8), 473; https://doi.org/10.3390/fishes11080473 - 13 Aug 2026

Viewed by 251

Abstract

Nonylphenol (NP), a typical emerging pollutant, is widely detected in water bodies, yet its hepatotoxic mechanisms and mitigation strategies remain underexplored. This study evaluated the protective effects of a mixed probiotic (Lactobacillus acidophilus and Bacillus subtilis) against NP-induced hepatotoxicity in Silurus [...] Read more.

Nonylphenol (NP), a typical emerging pollutant, is widely detected in water bodies, yet its hepatotoxic mechanisms and mitigation strategies remain underexplored. This study evaluated the protective effects of a mixed probiotic (Lactobacillus acidophilus and Bacillus subtilis) against NP-induced hepatotoxicity in Silurus meridionalis by integrating transcriptomic and metabolomic analyses, with validation by RT-qPCR and ELISA. The results showed that NP exposure disrupted the arachidonic acid (AA) pathway (activating pro-inflammatory COX and LOX pathways while the suppressing anti-inflammatory CYP450 branch), promoted ferroptosis via iron dyshomeostasis and oxidative damage, and impaired triglyceride (TG) synthesis. Probiotic pretreatment reversed these toxic effects by modulating AA metabolism, suppressing COX (ptgs2a↓ → PGE₂↓) and LOX (alox12↓ → MDA↓) pathways, while upregulating the CYP450 pathway (cyp2j↑ → 11,12-EET↑). Probiotics also enhanced Fe³⁺ sequestration (steap4↑) and antioxidant defense (CAT↑, gpx4a↑), limiting Fenton reaction-mediated oxidative injury, and restored hepatic TG synthesis through upregulation of the DHAP-to-TG cascade (DHAP—(gpd1b↑) → G3P↑—(gpat3↑) → LPA—(agpat6↑) → PA—(plpp7↑) → DAG↑—(dgat2↑) → TG↑). These findings suggest that NP induces hepatotoxicity in S. meridionalis, involving ferroptosis, AA metabolism disruption and impaired TG synthesis as interconnected pathological events. Probiotics likely counteract this toxicity through systemic metabolic reprogramming. Collectively, these findings elucidate the hepatotoxic mechanisms of NP in S. meridionalis and offer toxicological data for its risk assessment, supporting the potential of probiotic-based strategies to mitigate emerging pollutant impacts in aquatic organisms. Full article

(This article belongs to the Section Nutrition and Feeding)

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15 pages, 2823 KB

Open AccessReview

Cobamide Fingerprinting Reveals Nutritional Diversity of Vitamin B₁₂ in Edible Shellfish

by Fumio Watanabe, Kyohei Koseki and Tomohiro Bito

Fishes 2026, 11(8), 472; https://doi.org/10.3390/fishes11080472 - 13 Aug 2026

Viewed by 315

Abstract

In edible shellfish, vitamin B₁₂ content has traditionally been evaluated based on total content; however, recent studies reveal substantial diversity in corrinoid composition among species. This review integrates molecular and ecological perspectives to reassess vitamin B₁₂ levels in shellfish using cobamide [...] Read more.

In edible shellfish, vitamin B₁₂ content has traditionally been evaluated based on total content; however, recent studies reveal substantial diversity in corrinoid composition among species. This review integrates molecular and ecological perspectives to reassess vitamin B₁₂ levels in shellfish using cobamide fingerprinting. Filter-feeding bivalves generally exhibit vitamin B₁₂-dominant profiles, whereas herbivorous gastropods often contain higher proportions of pseudovitamin B₁₂, and carnivorous species display intermediate or vitamin B₁₂-dominant patterns reflecting trophic transfer. In addition, physicochemical form and food processing influence vitamin B₁₂ bioavailability. These findings collectively demonstrate that a precise nutritional assessment requires a comprehensive evaluation of both the total content and the molecular makeup of corrinoids. Full article

(This article belongs to the Special Issue Trends and Advances in Seafood Quality: Processing, Preservation and Safety Processes to Guarantee Food Value—2nd Edition)

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24 pages, 1238 KB

Open AccessArticle

Immune Responses and Protective Efficacy of Immersion and Intraperitoneal Vaccination Against Tenacibaculum maritimum in European Seabass (Dicentrarchus labrax)

by Ivana Giovanna Zupičić, Snježana Zrnčić, Lea Vrbančić, Donatella Volpatti, Marco Galeotti, Dražen Oraić, Matea Alfier and Dorotea Grbin

Fishes 2026, 11(8), 471; https://doi.org/10.3390/fishes11080471 - 12 Aug 2026

Viewed by 299

Abstract

Tenacibaculosis, caused by Tenacibaculum maritimum, remains a major bacterial disease affecting marine aquaculture, particularly European seabass farming. This study evaluated the immune response and protective efficacy of a formalin-inactivated T. maritimum vaccine administered by immersion or intraperitoneal (i.p.) injection in European seabass [...] Read more.

Tenacibaculosis, caused by Tenacibaculum maritimum, remains a major bacterial disease affecting marine aquaculture, particularly European seabass farming. This study evaluated the immune response and protective efficacy of a formalin-inactivated T. maritimum vaccine administered by immersion or intraperitoneal (i.p.) injection in European seabass (Dicentrarchus labrax). Each vaccination strategy was evaluated using its corresponding experimental challenge model 36 days post-vaccination. Vaccine performance was assessed by relative percentage of survival (RPS), expression of selected immune-related genes (IL-1β, IL-10, IgT), and specific serum IgM production. Intraperitoneal vaccination followed by i.p challenge provided significant protection, with 87% survival and an RPS of 67, accompanied by elevated serum IgM levels and pronounced systemic immune activation. Immersion-vaccinated fish also showed complete survival; however, the unexpectedly low mortality in the corresponding mock-vaccinated controls limited the discriminatory capacity of the immersion challenge model and prevented a robust assessment of vaccine efficacy according to the defined criteria. Gene expression analysis revealed distinct immune profiles, with immersion vaccination inducing an early but transient response, whereas i.p. vaccination elicited stronger and more sustained systemic activation, particularly within innate and humoral immune pathways. Principal component analysis further demonstrated clear clustering of immune responses according to vaccination route. These findings demonstrate the potential of an autogenous vaccine to protect European seabass against tenacibaculosis and highlight the importance of considering both vaccination route and the challenge model when interpreting vaccine efficacy. Further studies should optimise immersion vaccination protocols and investigate local mucosal immune responses to support the development of effective vaccination strategies for juvenile European seabass. Full article

(This article belongs to the Special Issue Fish Disease Prevention: Immune Defense and Vaccine Development)

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21 pages, 3494 KB

Open AccessArticle

An Analysis of Growth Characteristics and Population Dynamics of Cynoglossus gracilis in the Offshore Waters of Liaoning Province, China

by Lin Zhang, Yingyou Zhou, Zengqiang Yin, Qifa Zhang, Yikai Lan, Quan Yu, Jiahang Wei, Fan Du and Lei Chen

Fishes 2026, 11(8), 470; https://doi.org/10.3390/fishes11080470 - 12 Aug 2026

Viewed by 255

Abstract

This study investigated the population dynamics of Cynoglossus gracilis in the offshore waters of Liaoning Province, China, to support sustainable fisheries management. Biological samples were collected from five major fishing ports between March and November 2024. Population dynamics were assessed based on growth, [...] Read more.

This study investigated the population dynamics of Cynoglossus gracilis in the offshore waters of Liaoning Province, China, to support sustainable fisheries management. Biological samples were collected from five major fishing ports between March and November 2024. Population dynamics were assessed based on growth, mortality, and exploitation parameters, and four seasonal fishing closure scenarios were evaluated using egg production per recruit (EPR) and spawning biomass per recruit (SBR) models. The estimated exploitation rate (E = 0.53) indicated that the stock was experiencing relatively high fishing pressure but remained close to the sustainable exploitation reference level. Yield-per-recruit analysis suggested that increasing the minimum catchable size could improve resource utilization efficiency. Among the evaluated closure scenarios, the April–September closure provided the greatest conservation benefit by enhancing reproductive potential and protecting spawning stock biomass. These findings provide valuable insights for optimizing harvest regulations and seasonal closure strategies, contributing to the sustainable management of Cynoglossus gracilis resources in the offshore waters of Liaoning Province. Full article

(This article belongs to the Special Issue Adaptive Fisheries Management in East Asia: Navigating Climate Change, POPs, and Microplastics)

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20 pages, 2105 KB

Open AccessArticle

Evaluating the Environmental Parameters Associated with Spawning Movement of Gulf Sturgeon (Acipenser desotoi) in the Bouie River

by Olivia A. St. Germain, Paul O. Grammer, Alyssa M. Pagel, Mark S. Peterson, Kasea L. Price, William T. Slack and Michael J. Andres

Fishes 2026, 11(8), 469; https://doi.org/10.3390/fishes11080469 - 11 Aug 2026

Viewed by 424

Abstract

Gulf sturgeon are federally listed as “threatened” and are native to seven rivers along the northern Gulf of Mexico. Populations natal to the Pascagoula River have one verified spawning reach in the lower Bouie River, near Hattiesburg, MS. This reach is modified by [...] Read more.

Gulf sturgeon are federally listed as “threatened” and are native to seven rivers along the northern Gulf of Mexico. Populations natal to the Pascagoula River have one verified spawning reach in the lower Bouie River, near Hattiesburg, MS. This reach is modified by four aggregate mining areas, referred to as pits. Researchers observed post-spawn Gulf sturgeon over-summering in pits rather than migrating to downstream holding areas in the Pascagoula River. We leverage acoustic telemetry and environmental data to assess drivers of arrival and departure from the Bouie River, describe vertical stratification in the water column in pits, and compare pit temperatures to those in holding areas. Generalized mixed linear modeling demonstrated that arrival was associated with lower discharge rates, whereas departure was associated with higher surface water temperatures and greater daily temperature extremes. Sturgeon had varying occupancy rates in pits, with four over-summering events over 3 years. Stratification formed in the pits in May and persisted through October, with bottom and middle strata exhibiting cooler temperatures than holding habitats. Cooler bottom temperatures indicate potential for thermal refuge in the pits. However, persistent stratification leads to low dissolved oxygen in bottom waters, warranting further research into the environmental stressors of this system. Full article

(This article belongs to the Section Biology and Ecology)

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13 pages, 3737 KB

Open AccessArticle

Age Structure and Growth of the Japanese Spanish Mackerel (Scomberomorus niphonius) in Korean Waters

by Han Ju Kim, Hae-young Choi, Seong Yong Moon, Hae Won Lee, Jeong-hoon Lee and Sang Chul Yoon

Fishes 2026, 11(8), 468; https://doi.org/10.3390/fishes11080468 - 11 Aug 2026

Viewed by 282

Abstract

In this study, we estimated the age and growth of S. niphonius using otolith-based age determination. Five hundred and thirty individuals were sampled from commercial fisheries and the National Institute of Fisheries Science research vessels in Korean waters between January and December 2024 [...] Read more.

In this study, we estimated the age and growth of S. niphonius using otolith-based age determination. Five hundred and thirty individuals were sampled from commercial fisheries and the National Institute of Fisheries Science research vessels in Korean waters between January and December 2024 and from June to September 2025. Fork length ranged from 30.4 to 112.1 cm and body weight ranged from 218.2 to 9360 g. Sagittal otoliths were transversely sectioned and examined under a microscope. The age-reading precision between the two independent readers exhibited a high agreement (percentage agreement = 96.0%, average percentage error = 5.49%, coefficient of variation = 7.76%). The observed age ranges were 0–10.1 years for females and 0–8.1 years for males. Estimated parameters of the von Bertalanffy growth function were

L_{\infty} = 119.77

cm,

K = 0.41

year⁻¹, and

t_{0} = - 0.83

for females, and

L_{\infty} = 97.00

cm,

K = 0.59

year⁻¹, and

t_{0} = - 0.64

for males. Females exhibited larger asymptotic lengths but lower growth coefficients than those of males, and growth differed significantly between sexes. These results constitute the first study of age and growth based on otoliths in Korean waters and contribute to improving the biological understanding and management of this species. Full article

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

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20 pages, 5731 KB

Open AccessArticle

Modeling the Ecological Consequences of an Open-Sea Nuclear Release on Resident and Migratory Marine Fish in the North Atlantic

by Carmen Cortés and Raúl Periáñez

Fishes 2026, 11(8), 467; https://doi.org/10.3390/fishes11080467 - 10 Aug 2026

Viewed by 297

Abstract

Accidental releases of radionuclides from nuclear-powered vessels or ships carrying nuclear weapons may expose marine organisms to radioactive contaminants. The consequences of such events can differ markedly between resident fish populations and migratory species that move through affected areas. While these contrasting responses [...] Read more.

Accidental releases of radionuclides from nuclear-powered vessels or ships carrying nuclear weapons may expose marine organisms to radioactive contaminants. The consequences of such events can differ markedly between resident fish populations and migratory species that move through affected areas. While these contrasting responses have been evaluated by the authors for coastal nuclear accidents, comparable assessments for open-sea scenarios remain limited. We simulated radionuclide releases from vessels in the North Atlantic to evaluate exposure pathways and potential ecological effects on both resident and migratory fish, since several naval bases operating nuclear-powered vessels are located along the eastern North American coastline. Physical transport of radionuclides was modeled using a Lagrangian framework that incorporates advection by ocean currents, three-dimensional turbulent diffusion, radioactive decay, and dynamic sediment–water exchanges. This transport model was coupled to a four-compartment food-web bioaccumulation model representing phytoplankton, zooplankton, non-piscivorous fish, and piscivorous fish. The approach allows evaluation of contaminant uptake in resident fish populations and along the migration routes of highly mobile species. Bluefin tuna (Thunnus thynnus), a key ecological and commercially valuable species, was selected as the migratory case study. Migration paths reconstructed from electronic tagging data were integrated to estimate radionuclide exposure along individual trajectories. This combined modeling framework provides new insight into how open-sea nuclear releases may differentially affect resident fish communities and wide-ranging migratory species in the North Atlantic, with relevance for fish ecology, population risk assessment, and fisheries management. Full article

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

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17 pages, 1099 KB

Open AccessArticle

Optimizing RNA Delivery Strategies for Gilthead Seabream (Sparus aurata) SaB-1 Cells

by Sara Veiga-Rúa, Álvaro J. Arana, Alba Salgado-Roo, Catarina Allegue, Alberto Cuesta, Paulino Martínez, Laura Sánchez and Diego Robledo

Fishes 2026, 11(8), 466; https://doi.org/10.3390/fishes11080466 - 10 Aug 2026

Viewed by 261

Abstract

Aquaculture is the world’s fastest-growing food production sector, yet it faces major challenges, including limited understanding of the biology of farmed species. In this context, cell lines are becoming increasingly relevant for studying complex traits and their underlying genetic basis. The in vitro [...] Read more.

Aquaculture is the world’s fastest-growing food production sector, yet it faces major challenges, including limited understanding of the biology of farmed species. In this context, cell lines are becoming increasingly relevant for studying complex traits and their underlying genetic basis. The in vitro application of molecular tools—such as RNA interference and genome editing—can help disentangle the molecular basis of target traits. However, the lack of protocols for in vitro manipulation is limiting progress in the field. Here, we optimized RNA transfection protocols in SaB-1 cells derived from gilthead seabream, one of the most important farmed species in Mediterranean aquaculture. Despite its importance, in vitro research on this species has been scarce to date. Our results show that RNA delivery in this cell line can be achieved using either electroporation or FUGENE^®-SI-based chemical transfection, although electroporation resulted in lower survival (around 35% versus 76% for chemical transfection). Finally, as a proof-of-concept, both delivery strategies were tested for CRISPR/Cas9-mediated gfap gene editing, which was achieved with efficiencies of around 10%. This study provides useful methodological advances for functional genomics in aquaculture, offering RNA delivery that enables genome-editing strategies and can accelerate molecular research and trait improvement in gilthead seabream. Full article

(This article belongs to the Special Issue Functional Gene Analysis and Genomic Technologies in Aquatic Animals)

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0 pages, 3504 KB

Open AccessArticle

Scale-Dependent Microhabitat Choice of an Asian Minnow (Schizothorax grahami) in Heterogeneous Rock-Array Flows

by Biao Wang, Hongze Li, Huijuan Chen, Xiaogang Wang and Jianzhang Lv

Fishes 2026, 11(8), 465; https://doi.org/10.3390/fishes11080465 - 9 Aug 2026

Viewed by 219

Abstract

Fish can perceive and respond to local flow structures when selecting microhabitats, yet how scale-dependent hydrodynamic heterogeneity shapes behavioral habitat choice remains poorly understood. In this study, a multi-scale rock-array flow field was constructed using flume experiments, and the volitional swimming behavior of [...] Read more.

Fish can perceive and respond to local flow structures when selecting microhabitats, yet how scale-dependent hydrodynamic heterogeneity shapes behavioral habitat choice remains poorly understood. In this study, a multi-scale rock-array flow field was constructed using flume experiments, and the volitional swimming behavior of Schizothorax grahami was observed. Hydrodynamic parameters including velocity magnitude (U_mag), turbulent kinetic energy (TKE), and kinetic energy gradient (KEG) were analyzed. The results indicated that fish distribution changed with rock size: at a rock-element diameter of 0.12 m, fish were dispersed without forming stable high-utilization core areas; at 0.24 m, fish aggregated in the lee-side regions behind the rock elements; and at 0.50 m, fish shifted toward the upstream faces. The hydrodynamic variables significantly associated with fish microhabitat selection varied with rock-array scale: in the 0.24 m rock arrays, KEG differed significantly between high- and low-use units under all flow conditions; in the 0.50 m rock arrays, U_mag and TKE showed consistent and significant between-group differences across flow conditions. Moreover, cross-scale overlap analysis revealed that the utilization range of velocity magnitude had the highest overlap, followed by TKE, with KEG exhibiting the lowest overlap. Collectively, these findings support a hierarchical interpretation of fish microhabitat selection characterized by “velocity rigidity–turbulence elasticity,” providing a potential perspective for understanding differences in the hydrodynamic variables associated with fish microhabitat selection across studies. These results indicate that both mean velocity constraints and local turbulence-creating structures should be considered in river habitat restoration and roughness element configuration. Full article

(This article belongs to the Section Biology and Ecology)

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30 pages, 27025 KB

Open AccessArticle

Population Status and Conservation of Sterlet (Acipenser ruthenus L.) in the Transboundary Irtysh River Connecting China, Kazakhstan, and Russia: Evidence from Long-Term Monitoring and Broodstock Development

by Saule Zh. Assylbekova, Rinat T. Barakov, Nailya Bulavina, Aibek M. Kassymkhanov, Moldir Aubakirova, Angsar Satbek, Xia-Long Luo, Kuanysh B. Isbekov and Almat S. Suyubayev

Fishes 2026, 11(8), 464; https://doi.org/10.3390/fishes11080464 - 8 Aug 2026

Viewed by 340

Abstract

Restoration of natural sterlet (Acipenser ruthenus) stocks in the transboundary Irtysh River, shared by China, Kazakhstan, and Russia, is of critical importance for biodiversity conservation and represents a strategic priority for sustainable management of transboundary aquatic resources in all three countries. [...] Read more.

Restoration of natural sterlet (Acipenser ruthenus) stocks in the transboundary Irtysh River, shared by China, Kazakhstan, and Russia, is of critical importance for biodiversity conservation and represents a strategic priority for sustainable management of transboundary aquatic resources in all three countries. Over the past two decades, sterlet abundance and occurrence in the river have remained low, indicating an unfavorable population status. The Irtysh sterlet population is likely influenced by a combination of habitat degradation, fragmentation of spawning habitats, alterations in the hydrological regime, and increasing anthropogenic pressure. This study summarizes archival and recent data on sterlet catches, biological condition, and habitat characteristics within the Irtysh River basin. Hydrological and hydrochemical parameters, spatial distribution of catches, and the size–age structure of the population were analyzed. The results revealed a localized distribution pattern of sterlet, with the aggregation index reaching I ≥ 1 in some cases, indicating an uneven spatial distribution of individuals. Such aggregation patterns may partially reflect the presence of ecologically important habitats and provide a basis for future conservation planning and targeted monitoring, although this relationship could not be confirmed within the scope of the present study. A decline in the proportion of older age groups and deterioration of key biological indicators suggest weakening natural reproduction. The study initiated the establishment of a replacement broodstock and formed an initial broodstock of 34 sterlet individuals collected from the wild. This provides a foundation for future artificial propagation and the recovery of the endangered Irtysh River sterlet population. Full article

(This article belongs to the Special Issue Freshwater Fishes: Taxonomic Diversity, Conservation Concerns, and Future Directions)

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Fishes, Volume 11, Issue 8 (August 2026) – 63 articles

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