Fishes

18 pages, 3452 KB

Open AccessArticle

Numerical Simulation of Aquaculture-Derived Organic Matter Sedimentation in a Temperate Intensive Aquaculture Bay Based on a Finite-Volume Coastal Ocean Model

by Jing Fu, Ran Yu, Qingze Huang, Sanling Yuan and Jin Zhou

Fishes 2025, 10(10), 483; https://doi.org/10.3390/fishes10100483 - 28 Sep 2025

Abstract

In this study, a numerical model consisting of high-resolution hydrodynamic and Lagrangian particle tracking modules based on the Finite-Volume Coastal Ocean Model framework was established to simulate the hydrodynamic conditions and characteristics of the sedimentation of aquaculture-derived organic matter (AOM) from cage aquaculture [...] Read more.

In this study, a numerical model consisting of high-resolution hydrodynamic and Lagrangian particle tracking modules based on the Finite-Volume Coastal Ocean Model framework was established to simulate the hydrodynamic conditions and characteristics of the sedimentation of aquaculture-derived organic matter (AOM) from cage aquaculture in Sansha Bay. The results showed that Sansha Bay was characterized by regular semidiurnal tides and large tidal ranges. Reciprocating currents with main currents directed northward and southward during the rising and falling tides, respectively, predominated the main channels of the bay. Residual feed had larger settling velocities than feces. The maximal dispersion distances of residual feed and feces during the spring tide were 217.1 and 1805.7 m, respectively, three times those during the neap tide (74.2 and 675.6 m, respectively). During the spring tide, the largest dispersion distance of AOM occurred at the rush moment. The AOM movement trajectories were mainly controlled by the main currents. Both the tidal structure and current characteristics affected the AOM sedimentation in Sansha Bay. The sedimentation characteristics of AOM were unrelated to feeding intensity. The results of simulations agreed with the field observations in this study, suggesting that the estimated model had a good accuracy and sensitivity. Full article

(This article belongs to the Special Issue New Technologies for Improving Fisheries and Aquaculture Production and Management)

► Show Figures

Figure 1

17 pages, 1705 KB

Open AccessArticle

Effect of Dietary Proline on the Growth Performance, Collagen Deposition, and Texture Quality of Sea Cucumbers’ Body Wall (Apostichopus japonicus)

by Rujian Xu, Zitong Wang, Haijing Liu, Ruixue Li, Xianyu Wang, Hongbing Yang, Jun Ding, Yaqing Chang and Rantao Zuo

Fishes 2025, 10(10), 482; https://doi.org/10.3390/fishes10100482 - 26 Sep 2025

Abstract

Sea cucumber (Apostichopus japonicus) is an important economically cultured species in the northern coastal regions of China. Its body wall is rich in collagen, which directly determines product quality and market value. However, with the expansion of aquaculture scale, issues such [...] Read more.

Sea cucumber (Apostichopus japonicus) is an important economically cultured species in the northern coastal regions of China. Its body wall is rich in collagen, which directly determines product quality and market value. However, with the expansion of aquaculture scale, issues such as insufficient collagen deposition have led to inconsistent quality among cultured individuals. Therefore, there is an urgent need to improve growth performance and body wall quality through nutritional regulation. As functional nutrients, amino acids play key roles in collagen synthesis, yet relevant research on A. japonicus remains limited. This study was conducted to investigate the effects of dietary proline on the growth performance, body wall collagen deposition and organoleptic quality of sea cucumber (initial body weight: 30.20 ± 2.02 g). Three kinds of feed with equal levels of nitrogen and other lipids, and supplemented with different concentrations of proline (0%, 1.5%, 3%) in the basal diet, were named P0, P1.5, and P3, and the experiment was conducted for 60 days. The results showed that supplementation with 3% proline significantly increased final body weight and weight gain rate (p < 0.05), reaching 66.39 g and 115.30%, respectively. Collagen content in the body wall increased by approximately 18.5% compared to the control group. Histological analysis of the body wall showed that the collagen fibers in the P1.5 and P3 groups were thicker, with an increased proportion of type I collagen. Texture profile analysis indicated that hardness, cohesiveness, and chewiness were significantly improved in the P3 group (p < 0.05). In summary, supplementation with 1.5% and 3% proline effectively enhanced growth, collagen deposition, and body wall quality. Compared to the P0 group, the relative expression levels of collagen type I alpha 2 chain (COL1A1), Sma- and Mad-related protein 1(SMAD1), and sp-smad2/3 (SMAD2/3) in the body wall tissue were significantly upregulated in both the P1.5 and P3 groups (p < 0.05). Full article

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

► Show Figures

Figure 1

14 pages, 4048 KB

Open AccessArticle

Noctilucent Crab Pots in the Yellow Sea, China: Field Evidence for Catch Efficiency Enhancement and Sustainable Crab Fishery Practices

by Wei Liu, Minghua Min, Zhongqiu Wang, Yongli Liu, Lumin Wang and Xun Zhang

Fishes 2025, 10(10), 481; https://doi.org/10.3390/fishes10100481 - 26 Sep 2025

Abstract

Artificial light has been shown to enhance the fishing efficiency of fishing gear by attracting marine organisms. This study introduces a novel approach by incorporating noctilucent materials into crab pots and evaluates their effects on catch performance. Based on the crab pots commonly [...] Read more.

Artificial light has been shown to enhance the fishing efficiency of fishing gear by attracting marine organisms. This study introduces a novel approach by incorporating noctilucent materials into crab pots and evaluates their effects on catch performance. Based on the crab pots commonly used on the coast, four types of crab pots were tested: ordinary crab pots (Con-pot), ordinary crab pots equipped with noctilucent sticks (Exp-pot 1), crab pots equipped with noctilucent nets (Exp-pot 2), and crab pots equipped with both noctilucent nets and sticks (Exp-pot 3). The results showed that the noctilucent material exhibits 6 h persistent emission in darkness after just 10 min of solar charging. Exp-pot 3 could significantly enhance fishing efficiency, which increased by 63.84% compared to the Con-pot. The proportion of crabs in Exp-pot 3 was the highest (86.35%), and the individual weight of crabs in Exp-pot 3 was the heaviest (61.5 g), which was 38.30% heavier than that in the Con-pot. Notably, Exp-pots 2 and 3 demonstrated superior selectivity with higher W₅₀ values (53.01 g and 54.49 g), narrower SRs (33.04–72.98 g and 32.95–76.03 g), effectively balancing target catch retention with undersized crab release, indicated that noctilucent nets exhibited stronger weight selectivity for crabs compared to noctilucent sticks. These results demonstrate that functional materials have broad potential applications in fishing gear, which could enhance the catch efficiency and individual size of crab caught. Full article

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

► Show Figures

Graphical abstract

15 pages, 478 KB

Open AccessArticle

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

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))

► Show Figures

Figure 1

25 pages, 9694 KB

Open AccessArticle

Short- and Medium-Term Predictions of Spatiotemporal Distribution of Marine Fishing Efforts Using Deep Learning

by Shenglong Yang, Wei Wang, Tianfei Cheng, Shengmao Zhang, Yang Dai, Fei Wang, Heng Zhang, Yongchuang Shi, Weifeng Zhou and Wei Fan

Fishes 2025, 10(10), 479; https://doi.org/10.3390/fishes10100479 - 25 Sep 2025

Abstract

High-resolution spatiotemporal prediction information on fishing vessel activities is essential for formulating and effectively implementing fisheries policies that ensure the sustainability of marine resources and fishing practices. This study focused on the tuna longline fishery in the Western and Central Pacific Ocean (130° [...] Read more.

High-resolution spatiotemporal prediction information on fishing vessel activities is essential for formulating and effectively implementing fisheries policies that ensure the sustainability of marine resources and fishing practices. This study focused on the tuna longline fishery in the Western and Central Pacific Ocean (130° E–150° W, 20° S–20° N) and constructed a CLA U-Net deep learning model to predict fishing effort (FE) distribution based on 2017–2023 FE records and environmental variables. Two modeling schemes were designed: Scheme 1 incorporated both historical FE and environmental data, while Scheme 2 used only environmental variables. The model predicts not only the binary outcome (presence or absence of fishing effort) but also the magnitude of FE. Results show that in short-term predictions, Scheme 1 achieved F1 scores of 0.654 at the 0.5°-1-day scale and 0.763 at the 1°-1-day scale, indicating substantial improvement from including historical FE data. In medium-term predictions, Scheme 1 and Scheme 2 reached maximum F1 scores of 0.77 and 0.72, respectively, at the optimal spatiotemporal scale of 1°-30 days. The analysis also quantified the relative importance of environmental variables, with sea surface temperature (SST) and chlorophyll-a (Chl-a) identified as the most influential. These findings provide methodological insights for spatiotemporal prediction of fishing effort and support the refinement of fisheries management and sustainability strategies. Full article

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

► Show Figures

Graphical abstract

11 pages, 974 KB

Open AccessArticle

Validation of Using Multiplex PCR with Sex Markers SSM4 and ALLWSex2 in Long-Term Stored Blood Samples to Determine Sex of the North American Shortnose Sturgeon (Acipenser brevirostrum)

by Hajar Sadat Tabatabaei Pozveh, Salar Dorafshan, Tillmann J. Benfey, Jason A. Addison and Matthew K. Litvak

Fishes 2025, 10(10), 478; https://doi.org/10.3390/fishes10100478 - 25 Sep 2025

Abstract

Sex-specific information is crucial for sturgeon culture, conservation, and fisheries management. However, identifying their sex is difficult outside the spawning season. Two recently identified female-specific loci (AllWSex2 and SSM4) are conserved across many Acipenserid species, but they have not been validated for all [...] Read more.

Sex-specific information is crucial for sturgeon culture, conservation, and fisheries management. However, identifying their sex is difficult outside the spawning season. Two recently identified female-specific loci (AllWSex2 and SSM4) are conserved across many Acipenserid species, but they have not been validated for all species within this family. This study aimed to (1) determine whether SSM4 can be used to sex shortnose sturgeon, (2) develop and test a multiplex PCR technique using both ALLWSex2 and SSM4 for sexing shortnose sturgeon, (3) determine if long-term stored blood samples can be used to sex shortnose sturgeon, and (4) test the effect of storage temperature on DNA degradation. DNA was extracted from frozen RBC samples from 36 previously sexed fish. A multiplex PCR was set up using three pairs of primers: AllWSex2 and SSM4, as female-specific loci, and mtDNA, as an internal control. AllWSex2 and SSM4 allowed for perfect discrimination of sex. While long-term storage and storage temperature did cause DNA degradation, the signal was still strong enough after 8 years of cold storage for reliable sex determination. This suggests that researchers now have the ability to re-examine archived/frozen samples to determine the sex of their sturgeon. Full article

(This article belongs to the Section Genetics and Biotechnology)

► Show Figures

Figure 1

26 pages, 12387 KB

Open AccessArticle

Mapping for Larimichthys crocea Aquaculture Information with Multi-Source Remote Sensing Data Based on Segment Anything Model

by Xirui Xu, Ke Nie, Sanling Yuan, Wei Fan, Yanan Lu and Fei Wang

Fishes 2025, 10(10), 477; https://doi.org/10.3390/fishes10100477 - 24 Sep 2025

Abstract

Monitoring Larimichthys crocea aquaculture in a low-cost, efficient and flexible manner with remote sensing data is crucial for the optimal management and the sustainable development of aquaculture industry and aquaculture industry intelligent fisheries. An innovative automated framework, based on the Segment Anything Model [...] Read more.

Monitoring Larimichthys crocea aquaculture in a low-cost, efficient and flexible manner with remote sensing data is crucial for the optimal management and the sustainable development of aquaculture industry and aquaculture industry intelligent fisheries. An innovative automated framework, based on the Segment Anything Model (SAM) and multi-source high-resolution remote sensing image data, is proposed for high-precision aquaculture facility extraction and overcomes the problems of low efficiency and limited accuracy in traditional manual inspection methods. The research method includes systematic optimization of SAM segmentation parameters for different data sources and strict evaluation of model performance at multiple spatial resolutions. Additionally, the impact of different spectral band combinations on the segmentation effect is systematically analyzed. Experimental results demonstrate a significant correlation between resolution and accuracy, with UAV-derived imagery achieving exceptional segmentation accuracy (97.71%), followed by Jilin-1 (91.64%) and Sentinel-2 (72.93%) data. Notably, the NIR-Blue-Red band combination exhibited superior performance in delineating aquaculture infrastructure, suggesting its optimal utility for such applications. A robust and scalable solution for automatically extracting facilities is established, which offers significant insights for extending SAM’s capabilities to broader remote sensing applications within marine resource assessment domains. Full article

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

► Show Figures

Graphical abstract

13 pages, 3270 KB

Open AccessArticle

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

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)

► Show Figures

Figure 1

20 pages, 5339 KB

Open AccessArticle

Pyloric Caeca Number as a Growth-Associated Trait Provides a New Strategy for Selective Breeding in Mandarin Fish (Siniperca chuatsi)

by Jingyun Feng, Lijuan Cai, Zhi Zhu, Yixi Tao, Gang Xu, Yang Xue, Xuliang Zhai, Huiqing Mei, Xiaomin Miao, Hao Xu and Yun Li

Fishes 2025, 10(10), 475; https://doi.org/10.3390/fishes10100475 - 23 Sep 2025

Abstract

Mandarin fish (Siniperca chuatsi) is a commercially important species in China. The number of pyloric caeca, essential for digestion and nutrient absorption, varies considerably (198–386) among individuals, but its relation to growth remains unclear. In this study, 300 samples from the [...] Read more.

Mandarin fish (Siniperca chuatsi) is a commercially important species in China. The number of pyloric caeca, essential for digestion and nutrient absorption, varies considerably (198–386) among individuals, but its relation to growth remains unclear. In this study, 300 samples from the first filial generation (F1) of farmed wild stocks were reared for 56 days and grouped based on pyloric caeca number. Fish with more pyloric caeca (≥289) exhibited significantly higher weight gain rates (WGRs), specific growth rates (SGRs), and digestive enzyme activities compared to those with fewer caeca (≤229). The final body weight (FBW) and the WGR showed moderately positive correlations with caeca number. These results showed that pyloric caeca number may be a valuable trait for selective breeding. To explore its genetic basis, a genome-wide association study (GWAS) identified over 1.4 million SNPs across 24 chromosomes. Twelve SNPs were potentially associated with pyloric caeca number, and we successfully identified one SNP that could effectively distinguish groups with the extreme number of pyloric caeca. Candidate genes near significant loci were enriched in pathways related to cell proliferation, differentiation, and metabolic regulation. These findings suggest a potential association between pyloric caeca number and growth, providing a possible reference for future molecular breeding in mandarin fish. Full article

(This article belongs to the Section Genetics and Biotechnology)

► Show Figures

Graphical abstract

17 pages, 4918 KB

Open AccessArticle

Polystyrene Microplastics Induce Insulin Resistance and Glucose Metabolism Disorders in Grass Carp (Ctenopharyngodon idellus) via the Gut Microbiome–Metabolism Axis

by Fubin Zhang, Shuting Huang, Xueting Chen, Zhendong Qin and Li Lin

Fishes 2025, 10(10), 474; https://doi.org/10.3390/fishes10100474 - 23 Sep 2025

Abstract

Polystyrene microplastic (PS-MP) particles disrupt aquatic biological systems due to their persistence and high bioaccumulation potential, causing structural damage and inflammatory responses. PS-MPs also act as metabolic disruptors, affecting glucose metabolism and insulin signaling, although the mechanisms underlying these effects remain unclear. In [...] Read more.

Polystyrene microplastic (PS-MP) particles disrupt aquatic biological systems due to their persistence and high bioaccumulation potential, causing structural damage and inflammatory responses. PS-MPs also act as metabolic disruptors, affecting glucose metabolism and insulin signaling, although the mechanisms underlying these effects remain unclear. In this study, grass carp were exposed to 100 μg/L and 400 μg/L of polystyrene MPs for 30 days. Histopathological analysis showed the shortening of intestinal villi, vacuolization, and inflammatory infiltration. Antioxidant enzyme activities (SOD and CAT) were reduced, while the presence of tissue damage markers (GPT and GOT) was elevated, suggesting a biphasic oxidative stress response. Transcriptomic analysis revealed downregulation of genes related to metabolism and insulin signaling, especially at 400 μg/L. Gene set enrichment analysis (GSEA) highlighted pathways related to insulin resistance and type 2 diabetes, indicating the disruption of glucose metabolism. Microbiome analysis showed reduced diversity, expansion of Proteobacteria (opportunistic pathogens), and a decrease in beneficial bacteria like Bacillus. These shifts correlated with changes in the expression of key insulin signaling genes, emphasizing the role of host–microbiota interactions in metabolic imbalances. This study revealed that PS-MPs disrupt glucose metabolism and insulin signaling in grass carp through a combination of histological damage, oxidative stress, and microbiota dysbiosis. Full article

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

► Show Figures

Figure 1

12 pages, 651 KB

Open AccessArticle

The Involvement of Follicle-Stimulating Hormone in Testis Differentiation in Nile Tilapia

by He Gao, Tomomitsu Arai, Chak Aranyakanont, Dan Li, Megumi Tada and Shigeho Ijiri

Fishes 2025, 10(10), 473; https://doi.org/10.3390/fishes10100473 - 23 Sep 2025

Abstract

In Nile tilapia, one of the most important aquaculture species, males are larger than females, and an all-male monosex culture offers significant economic benefits. Although the pituitaries of genetic female (XX) and genetic male (XY) tilapia have identical expression levels of follicle-stimulating hormone [...] Read more.

In Nile tilapia, one of the most important aquaculture species, males are larger than females, and an all-male monosex culture offers significant economic benefits. Although the pituitaries of genetic female (XX) and genetic male (XY) tilapia have identical expression levels of follicle-stimulating hormone (fsh), FSH receptor (fshr) expression remains relatively low in XY-undifferentiated gonads and then increases following morphological sex differentiation. The expression patterns of genes related to androgen biosynthesis in XY-undifferentiated gonads are similar to those of fshr during testis differentiation. This might imply that FSH has a potential function in testis differentiation through regulating the expression of genes related to androgen biosynthesis. To determine whether FSH signaling regulated androgen biosynthesis, we microinjected recombinant FSH (rFsh) into XY larvae during the early sex-differentiation stage. We compared the expression of various genes related to testis differentiation after injection. The genes hsd3b, cyp17a1, dmrt1, and gsdf were found to have higher expression in the rFsh treatment group. These results suggest that FSH signaling can activate androgen biosynthesis by regulating steroidogenic enzymes, including hsd3b and cyp17a1. Moreover, injected rFsh can upregulate dmrt1, which has a positive effect on the expression of gsdf. Therefore, during testis differentiation and development, FSH plays a role in both androgen synthesis and the expression of genes related to testis differentiation in Nile tilapia. Full article

(This article belongs to the Special Issue Molecular Mechanisms of Fish Sex Differentiation and Sexual Plasticity)

► Show Figures

Figure 1

23 pages, 5049 KB

Open AccessArticle

Growth, Physiological Response, and Gill Health of Spotted Rose Snapper (Lutjanus guttatus) Reared at Different Salinities

by Jonathan Chacón-Guzmán, Ricardo Jiménez-Montealegre, Neil Duncan, Elman Calvo-Elizondo, Silvia Valverde-Chavarría, Junior Pastor Pérez-Molina, Adriana Rodríguez-Forero, Javier Segura-Badilla, Enoc Soto-Alvarado, Tifanny Corrales, Catalina Víquez, Marcela Suárez-Esquivel, Laura Castro-Ramírez, Yanis Cruz-Quintana and Enric Gisbert

Fishes 2025, 10(9), 472; https://doi.org/10.3390/fishes10090472 - 22 Sep 2025

Abstract

The physiological and gill health responses of juvenile spotted rose snapper (Lutjanus guttatus) were evaluated at four salinities—8, 16, 24, and 32‰—over a 70-day period. Fish reared at 8‰ exhibited the highest final body weight (126.8 ± 2.6 g), which was [...] Read more.

The physiological and gill health responses of juvenile spotted rose snapper (Lutjanus guttatus) were evaluated at four salinities—8, 16, 24, and 32‰—over a 70-day period. Fish reared at 8‰ exhibited the highest final body weight (126.8 ± 2.6 g), which was significantly higher than their congeners kept at 24‰ (116.0 ± 2.3 g) and 32‰ (116.0 ± 2.3 g). This superior growth at 8‰ coincides with the complete absence of parasitic monogenean infestations. In contrast, parasite prevalence increased with salinity, reaching 87.5% at 24‰, and was associated with gill pathologies like hyperplasia. Plasma osmolality and chloride levels decreased at lower salinities, while sodium and potassium levels showed a compensatory increase. Plasma cortisol and glucose levels remained stable across all treatments, indicating an absence of chronic stress. These findings suggest that the optimal rearing salinity for juvenile L. guttatus is near 8‰. The enhanced growth at this salinity appears to be the result of a net energy gain, stemming from a trade-off between the minor cost of osmoregulation in a hypo-osmotic environment and the major energetic benefit of avoiding parasitic disease. Full article

(This article belongs to the Special Issue Adaptation and Response of Fish to Environmental Changes)

► Show Figures

Figure 1

35 pages, 1628 KB

Open AccessReview

Feed Additives in Aquaculture: Benefits, Risks, and the Need for Robust Regulatory Frameworks

by Ekemini Okon, Matthew Iyobhebhe, Paul Olatunji, Mary Adeleke, Nelson Matekwe and Reuben Okocha

Fishes 2025, 10(9), 471; https://doi.org/10.3390/fishes10090471 - 22 Sep 2025

Abstract

Aquaculture currently supplies over half of the world’s fish and relies heavily on feed additives to enhance growth, improve feed efficiency, and increase disease resistance. This review consolidates peer-reviewed studies identified through targeted searches of Web of Science, Scopus, and Google Scholar, focusing [...] Read more.

Aquaculture currently supplies over half of the world’s fish and relies heavily on feed additives to enhance growth, improve feed efficiency, and increase disease resistance. This review consolidates peer-reviewed studies identified through targeted searches of Web of Science, Scopus, and Google Scholar, focusing on aquaculture feed additives. It emphasizes the principal classes of additives employed in finfish and shrimp cultivation, such as natural immunostimulants (including beta-glucans and nucleotides), probiotics, prebiotics, synbiotics, phytogenics, enzymes, and synthetic nutrients. For each, it summarizes their mechanisms of action, commonly reported inclusion rates, production outcomes, environmental risks, and regulatory statuses. Evidence indicates that immunostimulants enhance innate defences (including phagocyte activity and cytokine responses). Probiotics and prebiotics, on the other hand, regulate gut microbiota and barrier function. Phytogenics offer antimicrobial and antioxidant effects, and synthetic additives provide targeted nutrients or functional compounds that support growth and product quality. Where data are available, typical application ranges include probiotics in the order of 10⁴–10⁹ CFU per gram, prebiotics at approximately 2–10 g per kilogram, and pigments or antioxidants (such as astaxanthin) at 50–100 mg per kilogram. Significant gaps exist, notably the absence of species-specific dose–response data for tropical and subtropical aquaculture species, as well as limited experimental evidence regarding additive–additive interactions under commercial rearing conditions. Additional gaps include long-term ecological fate, regional regulatory discrepancies, and species-specific dose–response relationships. It is recommended that mechanistic studies employing omics approaches, standardised dose–response trials, and harmonized risk assessments be conducted to promote the sustainable and evidence-based application of feed additives. Full article

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

► Show Figures

Graphical abstract

16 pages, 1705 KB

Open AccessArticle

Compound Inhibitors Mitigate Skin Ulceration Induced by UVA and Vibrio splendidus in the Sea Cucumber Apostichopus japonicus

by Xiaonan Li, Ye Tian, Haoran Xiao, Fenglin Tian, Lingshu Han, Chong Zhao, Luo Wang and Jun Ding

Fishes 2025, 10(9), 470; https://doi.org/10.3390/fishes10090470 - 22 Sep 2025

Abstract

The sea cucumber (Apostichopus japonicus) is highly susceptible to environmental stress during aquaculture, storage, and transportation, often resulting in autolysis and considerable economic losses. UVA irradiation and Vibrio splendidus infection were used to induce skin ulceration in A. japonicus. In [...] Read more.

The sea cucumber (Apostichopus japonicus) is highly susceptible to environmental stress during aquaculture, storage, and transportation, often resulting in autolysis and considerable economic losses. UVA irradiation and Vibrio splendidus infection were used to induce skin ulceration in A. japonicus. In this study, UVA irradiation and V. splendidus infection were used to induce skin ulceration, and the effectiveness of a compound inhibitor in delaying its onset was evaluated. The degree of skin ulceration in A. japonicus was evaluated. Body wall tissues were collected to measure the activities of self-digesting enzymes, AchE, cathepsin L, SOD, and CAT. Caspase-3 expression was also analyzed to assess apoptosis and tissue damage. The results indicated that soaking A. japonicus in the inhibitor composition significantly delayed the onset of skin ulceration. After 72 h of UVA irradiation, the skin ulceration in group Eg was 0.55%, which was significantly lower than that in groups Cg and Wg. In the V. splendidus infection model, group Eg showed a 4-day delay in the onset of skin ulceration, compared to group Cg. Enzyme activity and gene expression analysis revealed that the inhibitor composition significantly reduced self-digesting enzyme expression in the A. japonicus body wall, increased SOD and CAT activities, and inhibited Caspase-3 expression. This study provides valuable theoretical insights into controlling skin ulceration in A. japonicus during aquaculture, preservation, and transportation. Full article

(This article belongs to the Special Issue Prevention and Control of Aquatic Animal Diseases)

► Show Figures

Figure 1

15 pages, 2137 KB

Open AccessArticle

Modulation of Gene Expression in the Digestive Tract of the Tropical Gar (Atractosteus tropicus) in Response to Cricket Meal (Acheta domesticus)

by Fanny Janet De la Cruz-Alvarado, Bartolo Concha Frías, María Guadalupe López-Cerino, Carlos Alfonso Álvarez-González, Gabriela Gaxiola-Cortés, Joe Luis Arias-Moscoso, Jaime Bautista-Ortega, Sergio Hernández-García and David Julián Palma-Cancino

Fishes 2025, 10(9), 469; https://doi.org/10.3390/fishes10090469 - 22 Sep 2025

Abstract

The tropical gar (Atractosteus tropicus Gill, 1863) is a prehistoric fish of high nutritional value in southern Mexico and Central America. However, some aspects related to the effects caused by alternative protein sources, such as insect meal, as a substitute for fish [...] Read more.

The tropical gar (Atractosteus tropicus Gill, 1863) is a prehistoric fish of high nutritional value in southern Mexico and Central America. However, some aspects related to the effects caused by alternative protein sources, such as insect meal, as a substitute for fish meal on the growth and expression of digestive enzyme genes, are still unknown. A total of 225 juveniles of A. tropicus were used and fed five experimental diets, each in triplicate, with different levels of substitution of fishmeal (FM) protein with house cricket meal (HCM) protein. A control diet that contained no HCM (T1-0% HCM) was used, and substitutions ranged from 25 to 100% of FM protein by HCM (T2-25% HCM, T3-50% HCM, T4-75% HCM, and T5-100% HCM) for 45 days. The results of this study indicate that T4-75% HCM showed the best growth indices, such as feed efficiency (EF), feed conversion ratio (FCR), specific growth rate (SGR), as well as higher gene expression of pepsin and trypsin, while chymotrypsin showed higher expression in T3. The higher performance achieved in T4-75% HCM may be due to the fact that, in the early stages, insects are part of the natural diet of A. tropicus. The inclusion of cricket meal as a partial substitute for fish meal is not recommended in quantities greater than T4-75%. Full article

(This article belongs to the Section Nutrition and Feeding)

► Show Figures

Graphical abstract

25 pages, 828 KB

Open AccessReview

From Gut to Fillet: Comprehensive Effects of Tenebrio molitor in Fish Nutrition

by Andrada Ihuț, Camelia Răducu, Paul Uiuiu and Camelia Munteanu

Fishes 2025, 10(9), 468; https://doi.org/10.3390/fishes10090468 - 20 Sep 2025

Abstract

As aquaculture expands, there is a growing demand for sustainable and environmentally friendly feed ingredients that can replace conventional fish meal while maintaining high biological value and digestibility. The use of fishmeal has contributed to overfishing, making it an increasingly limited and unsustainable [...] Read more.

As aquaculture expands, there is a growing demand for sustainable and environmentally friendly feed ingredients that can replace conventional fish meal while maintaining high biological value and digestibility. The use of fishmeal has contributed to overfishing, making it an increasingly limited and unsustainable resource. Tenebrio molitor (TM) is emerging as a sustainable alternative to fishmeal (FM) in aquaculture diets, gaining attention due to its balanced protein composition profile and low environmental footprint. This review critically analyses data from the literature on the use of TM meal as a substitute for fish feed ingredient, focusing on its effects on growth performance, physiological status, and histological changes in the digestive and muscular systems. The influence on the physicochemical and sensory quality of fish meat is also evaluated. The discussion highlights both the benefits and possible adverse effects, such as intestinal inflammation or changes that may occur, depending on the replacement level. The paper presents recommendations and strategies to mitigate these effects, including the use of dietary supplements or partial replacement schemes. Overall, this paper emphasises the promising potential of TM as a sustainable alternative to FM in aquaculture feed, while highlighting the need for further research into the long-term effects, involved metabolic pathways, and standardisation of insect meal production. This review provides valuable insight into the physiological changes that may occur, particularly at high inclusion levels. As TM is utilized in both human nutrition and aquaculture diets, monitoring its physiological effects in fish is essential, since any alterations may have implications for human food safety. Full article

(This article belongs to the Special Issue Dietary Supplementation in Aquaculture)

► Show Figures

Graphical abstract

16 pages, 1471 KB

Open AccessArticle

Fish Alone Are Not Enough: Zoobenthos Improves Water Quality Assessment in Impacted Rivers

by Ionuț Stoica, Karina P. Battes, Anca-Mihaela Șuteu Ciorca and Mirela Cîmpean

Fishes 2025, 10(9), 467; https://doi.org/10.3390/fishes10090467 - 19 Sep 2025

Abstract

This study examines fish communities in the heavily impacted Bistrița River, located in the Eastern Carpathians of Romania, where diffuse pollution from mining, domestic wastewater, agricultural and forestry activities emerged as the most severe pressures. Fish sampling was conducted at twenty sites across [...] Read more.

This study examines fish communities in the heavily impacted Bistrița River, located in the Eastern Carpathians of Romania, where diffuse pollution from mining, domestic wastewater, agricultural and forestry activities emerged as the most severe pressures. Fish sampling was conducted at twenty sites across two Natura 2000 protected areas. Results showed that species richness and diversity were higher downstream (Z1–Z5), indicating improved ecological conditions compared to the upstream section (B1–B15). The fish-based Index of Biological Integrity (IBI) suggested overall good biological integrity, with excellent conditions (class I) recorded in 70% of sites. Redundancy analysis (RDA) further revealed that elevation and conductivity significantly shaped community structure, while the site-specific impact score had only marginal effects. To assess water quality and biotic integrity based on different communities, as required by the Water Framework Directive (WFD), five sites were selected for parallel sampling of diatoms and benthic invertebrates. Among these, zoobenthos proved the most sensitive to water quality degradation, with biotic indices indicating classes I to III. These findings demonstrate that assessments based solely on fish may underestimate ecological impacts, underscoring the need for complementary approaches that account for multiple biotic communities when monitoring riverine ecosystem health. Full article

(This article belongs to the Special Issue Toxicology of Anthropogenic Pollutants on Fish)

► Show Figures

Graphical abstract

29 pages, 2477 KB

Open AccessArticle

Assessing the Effects of Species, Origin, and Processing on Frog Leg Meat Composition with Predictive Modeling Tools

by Marianthi Hatziioannou, Efkarpia Kougiagka and Dimitris Klaoudatos

Fishes 2025, 10(9), 466; https://doi.org/10.3390/fishes10090466 - 19 Sep 2025

Abstract

This study investigates the effects of species, geographical origin, and processing on the proximate composition of frog leg meat, with a focus on developing predictive models for processing status. Data were systematically compiled from 18 published studies, yielding 32 entries across 10 edible [...] Read more.

This study investigates the effects of species, geographical origin, and processing on the proximate composition of frog leg meat, with a focus on developing predictive models for processing status. Data were systematically compiled from 18 published studies, yielding 32 entries across 10 edible frog species and multiple processing methods. Proximate composition parameters (moisture, protein, fat, ash) were compared between processed and unprocessed samples, and classification models were trained using moisture content as the primary predictor. Logistic regression and several machine learning algorithms, including Stochastic Gradient Descent, Support Vector Machine, Random Forest, and Decision Tree, were benchmarked under a Leave-One-Study-Out (LOSO) cross-validation framework. Results demonstrated that moisture content alone was sufficient to accurately distinguish processing status, with a critical threshold of ~73% separating processed from unprocessed frog legs. Logistic regression achieved perfect specificity and precision (100%) with an overall accuracy of 96.8%, while other classifiers also performed strongly (>90% accuracy). These findings confirm moisture as a species- and origin-independent marker of processing, offering a simple, rapid, and cost-effective tool for authenticity verification and quality control in frog meat and potentially other niche protein products. Future work should expand sample coverage, validate thresholds across processing types, and integrate biochemical and sensory quality assessments. Full article

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

► Show Figures

Graphical abstract

15 pages, 2213 KB

Open AccessArticle

Strain-Specific Effects of Bacillus subtilis, Enterococcus faecium, and Pediococcus pentosaceus Supplementation on Growth Performance, Immunity, and Disease Resistance in Olive Flounder (Paralichthys olivaceus)

by Min-Kyeong Lee, Hyun-Kyoung Jung, Dong-Gyun Kim, In-Suk Park, Yu Li Heo, Jungha Kang and Young Sam Kim

Fishes 2025, 10(9), 465; https://doi.org/10.3390/fishes10090465 - 18 Sep 2025

Abstract

Olive flounder (Paralichthys olivaceus), a key aquaculture species in East Asia, is prone to stress and bacterial diseases under intensive farming. Antibiotics are often used to control these problems, but their overuse promotes resistance and threatens sustainability. To provide safer alternatives, [...] Read more.

Olive flounder (Paralichthys olivaceus), a key aquaculture species in East Asia, is prone to stress and bacterial diseases under intensive farming. Antibiotics are often used to control these problems, but their overuse promotes resistance and threatens sustainability. To provide safer alternatives, this study evaluated the strain-specific effects of dietary probiotics on growth, immunity, and disease resistance in olive flounder. A five-week feeding trial was conducted to evaluate the effects of three isolates—Bacillus subtilis, Enterococcus faecium, and Pediococcus pentosaceus—on growth, blood biochemistry, immune responses, and resistance against Edwardsiella tarda. Each strain was incorporated individually into a basal diet. After the feeding trial, probiotic supplementation improved growth performance. P. pentosaceus significantly increased final body weight and other growth indices (p < 0.05), while E. faecium yielded the lowest feed conversion ratio. Plasma glucose was markedly reduced in the E. faecium and P. pentosaceus groups (p < 0.001), whereas other biochemical indices remained stable. Phagocytic activity was significantly increased in the B. subtilis (p < 0.05) and P. pentosaceus (p < 0.01) groups, while lysozyme activity was significantly elevated in the E. faecium (p < 0.01) and P. pentosaceus (p < 0.05) groups. Following the E. tarda challenge, survival improved in all probiotic-fed groups (22.5–28.9%) compared with the control (11.5%). These findings demonstrate complementary, strain-specific benefits: P. pentosaceus enhanced growth, E. faecium improved feed efficiency and disease resistance, and B. subtilis stimulated immune responses. Validation under farm conditions and exploration of multi-strain formulations are warranted to optimize probiotic use in olive flounder aquaculture. Full article

(This article belongs to the Section Nutrition and Feeding)

► Show Figures

Figure 1

Journal Description

Fishes

Latest Articles

Journal Menu

Journal Browser

Highly Accessed Articles

Latest Books

E-Mail Alert

News

Topics

Conferences

Special Issues

Topical Collections

Further Information

Guidelines

MDPI Initiatives

Follow MDPI