Fishes

13 pages, 262 KB

Open AccessArticle

Optimizing Pellet Size and Feeding Strategy Using an Automatic Feeder in Juvenile Olive Flounder (Paralichthys olivaceus)

by Seong-Mok Jeong, Sang-Woo Hur, Jinho Bae and Byung Hwa Min

Fishes 2025, 10(9), 458; https://doi.org/10.3390/fishes10090458 - 11 Sep 2025

Abstract

Feeding is among the most labor-intensive tasks in aquaculture, yet it is critical for productivity and operational efficiency. Although automated feeding systems reduce labor, the absence of data on optimal pellet size, feeding rate, and frequency has led to inconsistent practices and productivity. [...] Read more.

Feeding is among the most labor-intensive tasks in aquaculture, yet it is critical for productivity and operational efficiency. Although automated feeding systems reduce labor, the absence of data on optimal pellet size, feeding rate, and frequency has led to inconsistent practices and productivity. We evaluated the applicability of a low-cost automatic feeder and determined optimal pellet size and feeding frequency for juvenile olive flounder (Paralichthys olivaceus) in an experiment where 600 fish (83.4 ± 0.7 g (mean ± SD)) were randomly assigned to 12 flow-through tanks (60 fish/tank) in triplicate. In Experiment 1, fish fed 5-mm pellets presented greater weight gain and protein efficiency ratio (PER) than those fed 3-mm pellets (p < 0.05). In Experiment 2, manual feeding was compared to automatic feeding. Fish fed three times per day at a 1.3% daily feed intake (DFI) achieved similar growth but an improved feed conversion ratio and PER compared to manually fed fish (p < 0.05). Our findings support the use of 5-mm pellets at 1.3% DFI with a low-cost automatic feeder for maintaining productive juvenile flounder. These results present a practical automation strategy that enables small and medium-sized aqua-farms to reduce labor while maintaining productivity equivalent to manual feeding. Full article

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

19 pages, 617 KB

Open AccessReview

Analysis of Edaphic Factors on the Role of Probiotics in the Development of Sustainable and Productive Aquaculture

by Dmitry Rudoy, Besarion Meskhi, Anastasiya Olshevskaya, Denis Kozyrev, Victoria Shevchenko, Mary Odabashyan, Svetlana Teplyakova and Alexander Rybak

Fishes 2025, 10(9), 457; https://doi.org/10.3390/fishes10090457 - 8 Sep 2025

Viewed by 225

Abstract

The use of antibiotics in aquaculture is associated with significant environmental risks, including ecosystem disruption and the accumulation of antibiotics in reservoirs and soil cover, as well as the spread of antibiotic-resistant strains, which encourages the search for sustainable alternatives, such as probiotics. [...] Read more.

The use of antibiotics in aquaculture is associated with significant environmental risks, including ecosystem disruption and the accumulation of antibiotics in reservoirs and soil cover, as well as the spread of antibiotic-resistant strains, which encourages the search for sustainable alternatives, such as probiotics. This review summarizes the research results on the use of probiotics in aquaculture systems. Special attention is paid to the action mechanisms and diverse effects on the health of aquatic animals, water quality and, most importantly, on the properties of soil in ponds. The research results show that certain strains of probiotics, in particular Bacillus spp., effectively decompose organic substances in sediments, reduce toxic metabolites’ concentration (ammonia, nitrites, hydrogen sulfide), stabilize soil structure, improve aeration and regulate sediments’ pH level and microbial diversity. However, the efficacy in field conditions can vary. Probiotics represent a science-based strategy to reduce dependence on antibiotics, increase system resilience by improving soil and water conditions, and increase productivity. In order to achieve maximum results, it is necessary to optimize the application methods, whilst taking into account local environmental factors. Full article

(This article belongs to the Special Issue Building a Sustainable Future for Inland Fisheries and Aquaculture in a Time of Multiple Stressors)

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13 pages, 656 KB

Open AccessArticle

The Influence of Rainbow Trout on Dwarf Galaxiid Habitat Preferences

by Ami Coughlan and Adam Canning

Fishes 2025, 10(9), 456; https://doi.org/10.3390/fishes10090456 - 5 Sep 2025

Viewed by 1198

Abstract

Introduced salmonids are a major threat to New Zealand’s non-migratory galaxiids, yet evidence for predator-driven habitat shifts remains limited. We experimentally tested whether dwarf galaxiids (Galaxias divergens) altered habitat use in response to rainbow trout (Oncorhynchus mykiss) presence or [...] Read more.

Introduced salmonids are a major threat to New Zealand’s non-migratory galaxiids, yet evidence for predator-driven habitat shifts remains limited. We experimentally tested whether dwarf galaxiids (Galaxias divergens) altered habitat use in response to rainbow trout (Oncorhynchus mykiss) presence or odour. Two habitat contrasts were offered: coarse versus fine substrate and open versus vegetated cover, under three predator treatments (trout-present, trout-odour-only, trout-absent). Generalised linear mixed models showed no significant effects of trout treatment on galaxiid habitat choice in either experiment. Substrate use was stable, with a consistent preference for coarse substrate regardless of predator cues, while vegetation cover had no detectable influence on behaviour. These results suggest that trout presence is unlikely to deter dwarf galaxiids from entire river reaches, but their limited behavioural response may leave them more exposed to predation where refuge is scarce. Habitat enhancement, particularly maintaining coarse substrate and reducing fine sediment, is likely to support the resilience of this short-lived, r-selected species. Full article

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

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14 pages, 1862 KB

Open AccessArticle

Antioxidant Responses of the Pacific Abalone Haliotis discus hannai to Turbidity Changes

by Jin Ah Song, Dong Mun Choi, Yun-Hwan Jung, Heung-Sik Park, Taihun Kim, Seog-Il Jang and Dae-Won Lee

Fishes 2025, 10(9), 455; https://doi.org/10.3390/fishes10090455 - 5 Sep 2025

Viewed by 196

Abstract

The increasing use of water-based drilling muds in offshore oil and gas operations has raised concerns about potential ecological risks of their primary components, such as bentonite, on marine organisms. To date, the biological effects of bentonite on benthic species remain poorly understood. [...] Read more.

The increasing use of water-based drilling muds in offshore oil and gas operations has raised concerns about potential ecological risks of their primary components, such as bentonite, on marine organisms. To date, the biological effects of bentonite on benthic species remain poorly understood. This study aimed to evaluate the physiological and oxidative stress responses of Pacific abalone (Haliotis discus hannai) exposed to varying concentrations (20–3000 mg/L) of bentonite over a 10-day period. Short-term exposure (up to 7 days) to bentonite did not result in significant mortality across treatment groups; however, partial mortality was observed in the highest concentration group (3000 mg/L) on day 8. Biochemical analyses revealed elevated levels of hydrogen peroxide and malondialdehyde, particularly in higher concentration groups, indicating oxidative stress. Antioxidant enzyme activities showed concentration- and time-dependent changes, with early activation followed by suppression under prolonged exposure. Total antioxidant capacity also declined over time in high-concentration groups. These findings indicate that while bentonite may not be acutely lethal to abalone, it can trigger sublethal oxidative stress responses, particularly under chronic exposure conditions, underscoring the importance of evaluating long-term physiological impacts of suspended drilling particulates and the need for research on a wider range of marine species. Full article

(This article belongs to the Section Aquatic Invertebrates)

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15 pages, 1041 KB

Open AccessArticle

Lipid and Fatty Acid Composition of Low-Value Mediterranean Fish in Winter and Spring for Discard Valorization

by Aristeidis Tsopelakos and Helen Miliou

Fishes 2025, 10(9), 454; https://doi.org/10.3390/fishes10090454 - 5 Sep 2025

Viewed by 184

Abstract

Winter and Spring variations of the fat and fatty acid compositions of discards from six species of the Aegean Sea were investigated to assess the potential suitability for human or aquaculture consumption. European pilchard (Sardina pilchardus), anchovy (Engraulis encrasicolus), [...] Read more.

Winter and Spring variations of the fat and fatty acid compositions of discards from six species of the Aegean Sea were investigated to assess the potential suitability for human or aquaculture consumption. European pilchard (Sardina pilchardus), anchovy (Engraulis encrasicolus), curled picarel (Centracanthus cirrus), gilt sardine (Saridenella aurita), horse mackerel (Trachurus mediterraneus) and bogue (Boops boops) were collected from the local fishing wharf during winter and spring. In most species, the specimens caught in spring exhibited elevated fat and n-3 long-chain polyunsaturated fatty acid content, with Sardina pilchardus showing an increase in DHA from 13.59% to 16.06% and Engraulis encrasicolus from 20.36% to 23.41% of the total identified fatty acids. Despite their lower commercial value, the high n-3 LC-PUFA content renders them nutritionally valuable and eligible for use by the aquafeed industry as an alternative to the increasingly costly fish oil. Moreover, in accordance with EU legislation banning discards and mandating the landing of unwanted catches, the valorisation of these species, in line with circular economy principles, could enhance fishers’ income, reduce waste and contribute to the long-term sustainability of marine ecosystems. Full article

(This article belongs to the Special Issue Recent Advances in Nutrition and Metabolic Regulation of Fish)

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27 pages, 10772 KB

Open AccessArticle

Preliminary Assessment of Age and Growth of the Red Swamp Crayfish Procambarus clarkii [Girard, 1852] in the River Nile in Egypt by Direct and Indirect Methods

by Mohamed Saeed, Raouf Kilada, Sahar Mehanna, Abdelhalim Saad and Magdy Khalil

Fishes 2025, 10(9), 453; https://doi.org/10.3390/fishes10090453 - 5 Sep 2025

Viewed by 315

Abstract

The red swamp crayfish (Procambarus clarkii) is an exceptionally invasive species introduced into the Egyptian freshwater ecosystems in the 1980s for aquaculture purposes. Despite its ecological and economic significance, the age distribution of this species has not been assessed properly using [...] Read more.

The red swamp crayfish (Procambarus clarkii) is an exceptionally invasive species introduced into the Egyptian freshwater ecosystems in the 1980s for aquaculture purposes. Despite its ecological and economic significance, the age distribution of this species has not been assessed properly using an accurate method. This study is the first to validate the use of growth band counts in the mesocardiac ossicles as a direct technique for age determination in P. clarkii using 166 known-age individuals reared under various temperature regimes. The findings confirm that band counts represent age rather than number of molts. Field comparisons between northern (Giza) and southern (Aswan) Nile populations revealed maximum longevities of six and seven years, respectively, using direct methods, while indirect size–frequency analysis underestimated age at three years. Growth rates were higher at 25 °C compared to 32 °C, both in the lab and in situ. Males matured at larger sizes than females, though age at sexual maturity averaged one year in both regions. This study demonstrates the superiority of direct aging over traditional indirect aging methods, offering critical insights for managing crayfish populations and ensuring sustainable fisheries in the River Nile in Egypt. Full article

(This article belongs to the Special Issue Age Determination of Aquatic Animals)

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15 pages, 12784 KB

Open AccessArticle

New Record of Saurida micropectoralis Shindo & Yamada, 1972 (Aulopiformes: Synodontidae) in the Southern Red Sea and Evidence of Range Expansion to East Africa

by Mohamed Hosny Gabr, Mohamed Ahmed Abu El-Regal, Mohsen Mohamed El-Sherbiny, Mamdouh Aly Al-Harby and Jean-Dominique Durand

Fishes 2025, 10(9), 452; https://doi.org/10.3390/fishes10090452 - 5 Sep 2025

Viewed by 180

Abstract

The shortfin lizardfish Saurida micropectoralis is recorded here for the first time from Jizan, Southern Red Sea, based on morphological and molecular analyses. This species closely resembles both S. tumbil and S. lessepsianus. However, S. micropectoralis is characterized by translucent whitish pelvic [...] Read more.

The shortfin lizardfish Saurida micropectoralis is recorded here for the first time from Jizan, Southern Red Sea, based on morphological and molecular analyses. This species closely resembles both S. tumbil and S. lessepsianus. However, S. micropectoralis is characterized by translucent whitish pelvic fins (vs. dusky in S. tumbil), indistinct blackish spots on the upper margin of the caudal fin (vs. distinct black spots (6–8) in S. lessepsianus), a short pectoral fin that never reaches the origin of the pelvic fin (vs. reaching a little beyond the base of the pelvic fin in S. lessepsianus), three rows of teeth on the outer palatines (vs. two rows in S. lessepsianus) and a pale whitish stomach and intestine (vs. greyish or black anteriorly in S. lessepsianus). Molecular analyses based on COI haplotypes confirmed the species-level identification but also revealed the existence of four distinct lineages across the species distribution range. The COI data revealed a clear geographic partitioning of haplotypes, indicating restricted gene flow and suggesting the presence of four cryptic species or, at minimum, independent evolving evolutionary units within Saurida micropectoralis. Populations of the shortfin lizardfish are well established in the Southern Red Sea and belong to a genetic lineage reported along the East African coast (Madagascar, Mozambique and Tanzania) and India. Full article

(This article belongs to the Special Issue Integrative Taxonomy and Molecular Systematics of Fishes)

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20 pages, 4664 KB

Open AccessArticle

Hawthorn Polysaccharide Enhances Growth, Immunity, and Intestinal Health in Crucian Carp (Carassius auratus) Challenged with Aeromonas hydrophila

by Liang Luo, Zhigang Zhao, Shihui Wang, Rui Zhang, Kun Guo, Cheng Zhao, Baoquan He, Wei Wang and Wenhua Wu

Fishes 2025, 10(9), 451; https://doi.org/10.3390/fishes10090451 - 5 Sep 2025

Viewed by 217

Abstract

Bacterial disease infections pose a major challenge to the healthy growth of crucian carp. Hawthorn polysaccharide (HP) is a natural active ingredient in hawthorn and has a wide range of pharmacological effects. However, the mechanism of HP against Aeromonas hydrophila infection in crucian [...] Read more.

Bacterial disease infections pose a major challenge to the healthy growth of crucian carp. Hawthorn polysaccharide (HP) is a natural active ingredient in hawthorn and has a wide range of pharmacological effects. However, the mechanism of HP against Aeromonas hydrophila infection in crucian carp cultures is unknown. In this study, it was found that 0.4% HP could significantly reduce the mortality of crucian carp, significantly increase the activities of T-AOC, SOD, CAT, and GSH-PX of crucian carp infected with A. hydrophila (p < 0.05), decrease the activity of MDA, and decrease the expression levels of TGF-β, TNF-α, IFN-γ, and IL-8 genes. Increased IL-10 gene expression levels (p < 0.05) significantly improved the disease resistance of crucian carp. HP could relieve intestinal inflammation caused by A. hydrophila infection, restoring intestinal structural integrity. At the same time, HP increased the diversity and improved the structure of intestinal microbiota. At the phylum level, the abundance of Proteobacteria and Firmicutes increased, while that of Bacteroidota and Fusobacteriota decreased. At the genus level, the abundance of Aeromonas increased, while the abundance of Cetobacterium decreased. Non-targeted metabolomics analysis of crucian carp LC-MS revealed 147 different metabolites, 62 of which were up-regulated and 85 of which were down-regulated, and Linoleic acid metabolism and Glycerophospholipids were one of the most important metabolic pathways. In conclusion, the supplementation of HP in feed can promote the healthy breeding of crucian carp, and the effect of resisting A. hydrophila is better. Full article

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

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22 pages, 4114 KB

Open AccessArticle

Modeling Skipjack Tuna Purse Seine Fishery Distribution in the Western and Central Pacific Ocean Under ENSO Scenarios: An Integrated MGWR-BME Framework

by Yuhan Wang, Xiaoming Yang, Menghao Li and Jiangfeng Zhu

Fishes 2025, 10(9), 450; https://doi.org/10.3390/fishes10090450 - 4 Sep 2025

Viewed by 214

Abstract

The Western and Central Pacific Ocean (WCPO), the key global purse seine fishing ground for skipjack tuna (Katsuwonus pelamis), sees frequent ENSO events. These events drastically alter marine ecosystems and fishery resource patterns, complicating fisheries management—given skipjack tuna’s high mobility and [...] Read more.

The Western and Central Pacific Ocean (WCPO), the key global purse seine fishing ground for skipjack tuna (Katsuwonus pelamis), sees frequent ENSO events. These events drastically alter marine ecosystems and fishery resource patterns, complicating fisheries management—given skipjack tuna’s high mobility and sensitivity to marine environmental changes. To address this, the study proposes an improved spatial prediction framework that incorporates the MGWR model to capture environmental changes. The spatial regression results generated by the MGWR model are incorporated as the mean-field input for the BME model. Additionally, the interannual standard deviation of skipjack tuna resources is fed into the BME model as a measure of spatial uncertainty. The results indicate that the mean field and uncertainty field exhibit a strong correlation, with an R² of 0.54, an RMSE of 583.32, an MAE of 377.22, and an ME of 334.77. Compared to the single prediction models BME and MGWR, the MGWR-BME integrated framework has improved R² by 12%, 30%, and 13% in the 2021–2023 predictions, respectively. Additionally, its prediction performance for distinguishing El Niño, La Niña, and normal years has significantly improved, with R² increasing from 0.6 to 0.67 in 2021, from 0.34 to 0.62 in 2022, and from 0.30 to 0.40 in 2023. According to the evaluation results based on Kernel Density Estimation (KDE) curves, the model performs well in fitting low values but shows weaker performance in fitting high values. By applying this approach, we have clarified the multiscale driving mechanisms through which marine environmental heterogeneity affects the distribution of skipjack tuna under ENSO conditions. This insight enables fishery managers to more accurately predict the dynamic changes in skipjack tuna fishing grounds under different climatic scenarios, thereby providing a reliable scientific basis for formulating rational fishing quotas, optimizing fishing operation layouts, and implementing targeted conservation measures—ultimately contributing to the balanced development of fishery resource utilization and ecological protection. Full article

(This article belongs to the Special Issue Modeling Approach for Fish Stock Assessment)

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25 pages, 11592 KB

Open AccessArticle

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

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

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

Viewed by 299

Abstract

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

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

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

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16 pages, 589 KB

Open AccessArticle

Use of Essential Oil from Aloysia citrodora Paláu in Anesthesia and Simulated Transport of Tambaqui Colossoma macropomum (Cuvier 1826) at Two Different Cargo Densities

by Orlando Pinto de Almeida Castro Neto, Patrick Jordan Correia-Silva, Isabelle Santos Silva, Aline dos Anjos Santos, Aline da Silva Rocha, Ricardo David Couto, Erick dos Santos Silva, Denise Schmidt and Carlos Eduardo Copatti

Fishes 2025, 10(9), 448; https://doi.org/10.3390/fishes10090448 - 3 Sep 2025

Viewed by 295

Abstract

This study evaluated the effectiveness of essential oil from Aloysia citrodora (EOAC) (48% citral and 19% limonene) for use in anesthesia and simulated transport of tambaqui (Colossoma macropomum) juveniles at two cargo densities (CDs). Concentrations of 0 (control), 10, 25, 50, [...] Read more.

This study evaluated the effectiveness of essential oil from Aloysia citrodora (EOAC) (48% citral and 19% limonene) for use in anesthesia and simulated transport of tambaqui (Colossoma macropomum) juveniles at two cargo densities (CDs). Concentrations of 0 (control), 10, 25, 50, 100, 150, 200, and 250 µL EOAC L⁻¹ were tested for use in anesthesia induction and recovery, while 0 (control) and 20 µL EOAC L⁻¹ were tested for their effects on the ventilatory rate (VR) and during 6 h simulated transport at a low CD (LCD, 65 g L⁻¹) and standard CD (SCD, 130 g L⁻¹). Fish were anesthetized at EOAC concentrations above 50 µL L⁻¹, with the optimal anesthesia (141.83 s) and recovery times (160.00 s) at 250 µL L⁻¹. The water unionized ammonia was lowest in the EOAC-LCD group. Using 20 µL EOAC L⁻¹ during transport minimized changes in the hematological parameters (erythrocytes, hemoglobin, hematocrit, total leukocytes, and heterophils) and reduced the liver aspartate aminotransferase activity at both CDs. Transport at an SCD, regardless of EOAC use, increased the plasma glucose, hepatic glycogen, and alanine transaminase activity. The VR was higher with 20 µL EOAC L⁻¹ than in the control group. In conclusion, our findings confirm that 20 µL EOAC L⁻¹ can effectively be used to transport tambaqui for up to 6 h without impairing fish health. Full article

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

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24 pages, 1274 KB

Open AccessArticle

Integration of Ulva ohnoi in a Recirculating Aquaculture System for Gilthead Seabream (Sparus aurata) and Its Use as Feed for Sea Urchin (Paracentrotus lividus) Production: A Contribution to Circular and Sustainable Aquaculture Practices

by João Araújo, Ana Catarina Carvalho, Ana Carolina Matias, Maria Carolina Ribeiro, Florbela Soares and Pedro Pousão-Ferreira

Fishes 2025, 10(9), 447; https://doi.org/10.3390/fishes10090447 - 3 Sep 2025

Viewed by 287

Abstract

This study evaluated the performance of a recirculating aquaculture system (RAS) integrated with macroalgae (Ulva ohnoi) cultivation and sea urchin (Paracentrotus lividus) feeding, in a multi-trophic aquaculture approach. This system aimed to enhance sustainability through water bioremediation by macroalgae [...] Read more.

This study evaluated the performance of a recirculating aquaculture system (RAS) integrated with macroalgae (Ulva ohnoi) cultivation and sea urchin (Paracentrotus lividus) feeding, in a multi-trophic aquaculture approach. This system aimed to enhance sustainability through water bioremediation by macroalgae and valorization of the algal biomass as echinoderms feed. Over a 180-day trial, biomass production of U. ohnoi remained stable, with daily growth rates ranging from 7.4 to 24.4%. Statistical analyses (PCA and GAM) indicated no significant linear or non-linear relationship between macroalgae growth and environmental parameters (temperature, radiation, photoperiod). A theoretical estimate of nutrient production showed fairly stable values that do not statistically explain biomass production variation, highlighting the species’ adaptability. Sea urchins fed with fresh U. ohnoi showed regular growth, supporting the nutritional suitability of this macroalgae. For fish (Sparus aurata), no significant differences in growth or feed conversion ratio were observed between systems with and without algae. Parasitological monitoring revealed lower parasite loads and egg deposition in tanks in recirculation with U. ohnoi during certain periods, suggesting a potential role of macroalgae in reducing monogenean propagation. These findings underscore the feasibility of integrating Ulva cultivation into RAS, contributing to circular aquaculture models with improved sustainability and resource efficiency. Full article

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14 pages, 2577 KB

Open AccessArticle

Effect of Dandelion Root Extract on Growth, Biochemical Indices, Antioxidant Capacity, Intestinal Histomorphology and Microbiota in Micropterus salmoides

by Peng-Ao Liu, Hong-Ling Yang, Jian Huang, Fen Li, Ke-Yun Huang, Zi-Xin Liu, Guo-He Cai and Yun-Zhang Sun

Fishes 2025, 10(9), 446; https://doi.org/10.3390/fishes10090446 - 3 Sep 2025

Viewed by 247

Abstract

Intensive aquaculture systems face challenges including compromised immune function and hepatointestinal damage in cultured species. Therefore, it is urgent to seek effective feed additives to strengthen health and immunity in intensive aquaculture. This study evaluated the potential of dandelion root extract (DRE) for [...] Read more.

Intensive aquaculture systems face challenges including compromised immune function and hepatointestinal damage in cultured species. Therefore, it is urgent to seek effective feed additives to strengthen health and immunity in intensive aquaculture. This study evaluated the potential of dandelion root extract (DRE) for improving growth performance, immune response, and hepatointestinal health in juvenile largemouth bass (Micropterus salmoides). Fish were fed diets supplemented with 0.05% (DRE1), 0.1% (DRE2), and 0.15% (DRE3) DRE for 42 days. The results showed that DRE supplementation had no significant effect on growth performance indicators (p > 0.05). However, compared to the control group, the DRE2 and DRE3 groups exhibited significantly reduced AST and ALT activities (p < 0.05). Lysozyme (LZM) activity increased significantly in all DRE groups, while alkaline phosphatase (AKP) activity was significantly elevated in the DRE2 and DRE3 groups (p < 0.05). In the liver, catalase (CAT) activity was significantly higher in the DRE2 group compared to the control (p < 0.05), and total antioxidant capacity (T-AOC) was significantly enhanced in DRE2 (p < 0.05). DRE also improved intestinal morphology, with significantly greater muscularis thickness in DRE2 and villus height in DRE3 compared to the control (p < 0.05). Also, serum D-lactate content was significantly decreased in all DRE-supplemented groups. Regarding intestinal microbiota, DRE2 supplementation resulted in an increased relative abundance of beneficial bacteria (Firmicutes) and a decreased relative abundance of potentially pathogenic bacteria (Proteobacteria), indicating favorable restructuring of the gut microbiota by DRE. In conclusion, dietary DRE supplementation, notably at 0.10%, enhanced antioxidant capacity and immunity while improving hepatointestinal health in largemouth bass, demonstrating potential as a functional feed additive in aquaculture. Full article

(This article belongs to the Special Issue Intestinal Health of Aquatic Organisms)

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19 pages, 1137 KB

Open AccessArticle

Biomarker-Based Assessment of Four Native Fish Species in the Danube River Under Untreated Wastewater Exposure

by Karolina Sunjog, Srđan Subotić, Jovana Kostić, Nebojša Jasnić, Branka Vuković-Gačić, Mirjana Lenhardt and Željka Višnjić-Jeftić

Fishes 2025, 10(9), 445; https://doi.org/10.3390/fishes10090445 - 3 Sep 2025

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Abstract

This study assessed the impact of untreated wastewater discharge in the Danube River on four native fish species: barbel (Barbus barbus), vimba bream (Vimba vimba), perch (Perca fluviatilis), and white bream (Blicca bjoerkna). Biomarkers of [...] Read more.

This study assessed the impact of untreated wastewater discharge in the Danube River on four native fish species: barbel (Barbus barbus), vimba bream (Vimba vimba), perch (Perca fluviatilis), and white bream (Blicca bjoerkna). Biomarkers of exposure and effect were evaluated, including metal and metalloid bioaccumulation in gills, liver, and gonads, DNA damage (comet assay), chromosomal abnormalities (micronucleus assay), liver enzyme activities (ALT, AST), and erythrocyte maturation. White bream showed the highest genotoxic damage (TI% = 22.57), particularly in liver tissue, indicating high sensitivity to pollution. Perch had elevated DNA damage in blood (TI% = 22.69) and strong biomarker responses, likely due to its predatory behavior. Barbel displayed notable DNA damage in gills (TI% = 30.67) and liver (TI% = 20.35), aligning with sediment exposure due to its benthic habits. Vimba bream had the lowest responses, possibly reflecting reduced exposure or resilience. Element accumulation varied across tissues and species, with perch showing the highest overall levels. Hepatic enzyme activities (highest values: ALT = 105.69 in barbel; AST = 91.25 in white bream) and changes in erythrocyte profiles supported evidence of physiological stress. Integrated Biomarker Response (IBR) analysis identified white bream as the most sensitive species, followed by perch and barbel. These results emphasize the value of multi-species biomonitoring and the importance of species-specific traits in freshwater ecotoxicology. Full article

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

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9 pages, 176 KB

Open AccessConference Report

The Aquatic Animal Welfare Research and Practice Seminar: Strengthen Animal Welfare Research and Application to Promote Sustainable Development of the Seafood Industry

by Zhangying Ye, Lu Chen, Hans van de Vis, Shaojun Liu, Ying Liu, Tore S. Kristiansen, Jian Zhu, Sonia Rey Planellas, Dapeng Li, Liuyi Huang, Michael Breen, Lynne U. Sneddon, María J. Cabrera-Álvarez and Jian Zhao

Fishes 2025, 10(9), 444; https://doi.org/10.3390/fishes10090444 - 3 Sep 2025

Viewed by 221

Abstract

Aquatic animal welfare has been gaining increasing attention globally in the last few years. The Aquatic Animal Welfare Research and Practice Seminar was held in Hangzhou, China, from 28th to 29th March 2025. The Seminar gathered leading scientists and industry stakeholders from across [...] Read more.

Aquatic animal welfare has been gaining increasing attention globally in the last few years. The Aquatic Animal Welfare Research and Practice Seminar was held in Hangzhou, China, from 28th to 29th March 2025. The Seminar gathered leading scientists and industry stakeholders from across the world who presented their recent research in aquatic animal welfare. This report presented the seminar’s key outcomes and discussions, highlighting current advances, challenges and future directions in aquatic animal welfare research and implementation. Full article

(This article belongs to the Section Physiology and Biochemistry)

15 pages, 3425 KB

Open AccessArticle

A Complicated History of Mitogenome Introgression Among Luxilus Species (Teleostei, Family Leuciscidae) in the Ozark Highlands

by David D. Duvernell, Carson Arnold, Shila Koju, Abby J. Wicks and Thomas E. Dowling

Fishes 2025, 10(9), 443; https://doi.org/10.3390/fishes10090443 - 3 Sep 2025

Viewed by 356

Abstract

Hybridization is common among minnows and shiners in the family Leuciscidae, and mitonuclear discordance can reveal evidence of historical hybridization and introgression events that have shaped extant species and populations. We have identified a notable case of serial mitogenome replacement in populations of [...] Read more.

Hybridization is common among minnows and shiners in the family Leuciscidae, and mitonuclear discordance can reveal evidence of historical hybridization and introgression events that have shaped extant species and populations. We have identified a notable case of serial mitogenome replacement in populations of two shiner species, Luxilus zonatus and L. chrysocephalus, which are syntopic in drainages throughout the northern and eastern Ozark Interior Highlands of North America. These mitogenome replacement events involved L. zonatus acquiring the mitogenome of L. chrysocephalus, and populations of L. chrysocephalus acquiring the mitogenome of an allopatric congeneric species, L. cornutus. The latter species has a more northern distribution that was likely shifted southward by glacial advances during the Pleistocene. The geographic extent of mitogenome replacements in both species spans multiple separate drainages encompassing most of the major river systems that comprise the northern and eastern Ozark Highlands. We attribute these patterns to shifting species distributions, which were impacted by multiple glacial advances and coincident geomorphological changes to Ozark Highland drainages throughout the Pleistocene. The serial nature of mitogenome replacements in L. zonatus and L. chrysocephalus may exclude a role for natural selection in these introgression events, but the dynamic shifts in species distributions and gene flow connections throughout the Pleistocene may have favored an invasion-with-hybridization model that predicts massive asymmetric introgression between invading and resident species. These results have applied significance for eDNA metabarcoding methods of biodiversity assessment in Ozark streams, as they are dependent on mitogenome detections. Full article

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

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19 pages, 321 KB

Open AccessReview

Fish Stock Assessment Models for Developing Nations with Emphasis on the Use of the Classic Gordon–Schaefer Model: A Review

by Francisco Chamera, Mphatso Kamndaya, Solomon Kadaleka, Patrick Phepa, Peter Mpasho Mwamtobe and Alpha Soko

Fishes 2025, 10(9), 442; https://doi.org/10.3390/fishes10090442 - 3 Sep 2025

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Abstract

The paper discusses fish stock assessment methods, emphasising methods for assessing stocks in developing nations. We present the advantages and disadvantages of each method discussed. Approaches to fish stock assessment include single-species, multi-species, multi-gear and ecosystem approaches. We discuss the Gordon–Schaefer (GS) model, [...] Read more.

The paper discusses fish stock assessment methods, emphasising methods for assessing stocks in developing nations. We present the advantages and disadvantages of each method discussed. Approaches to fish stock assessment include single-species, multi-species, multi-gear and ecosystem approaches. We discuss the Gordon–Schaefer (GS) model, a single-species surplus production model, as an alternative method for assessing fishery stocks in developing nations, with Malawi as an example of a developing nation. Although the GS model is not a contemporary method, it is still suitable for the situation in Malawi. We review how the GS model has been applied globally, in general, and in Malawi, in particular. The review shows that most studies have concentrated on the calculation of maximum sustainable yield or maximum economic yield, leaving out open access yield and optimum sustainable yield which is the dynamic reference point. Using all reference points is crucial in making correct management decisions. Bifurcation analysis, calculation of annual sustainable production, and calculation of depletion are missing in most studies. Future research should focus on integrating the use of all four reference points, bifurcation analysis, and calculation of depletion as well as annual sustainable production. Full article

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

12 pages, 1687 KB

Open AccessArticle

Reproductive Ecology of the Java Rabbitfish, Siganus javus, in the Southern South China Sea

by Takaomi Arai, Iy Vonne Tan, Fui Fui Ching and Norhayati Ahmad

Fishes 2025, 10(9), 441; https://doi.org/10.3390/fishes10090441 - 3 Sep 2025

Viewed by 330

Abstract

Fish reproductive biology influences their life history and can impact their vulnerability to fisheries; therefore, for sustainable management and development, a proper understanding is crucial. Reproductive biology, including maturation, spawning season, fecundity, and sex ratio, was examined throughout the year in the Java [...] Read more.

Fish reproductive biology influences their life history and can impact their vulnerability to fisheries; therefore, for sustainable management and development, a proper understanding is crucial. Reproductive biology, including maturation, spawning season, fecundity, and sex ratio, was examined throughout the year in the Java Rabbitfish, Siganus javus, in the southern South China Sea. This study is the first to examine reproductive traits by collecting a total of 339 S. javus specimens monthly from September 2017 to August 2018 through detailed gonad histology. The spawning season of female S. javus was mainly restricted to July, August, October, and December, whereas male fish were found to spawn throughout the year. Inter-species variations in the spawning season were observed within the genus, which is influenced by interspecific spawning strategies and regional environmental factors. The sex ratio close to 1:1 suggests that the fish population is in equilibrium in the region. The fecundity of S. javus ranged from 1.8 × 10⁵ to 12 × 10⁵, which was similar to that of other species in Siganus, suggesting less inter- and intra-species variation in fecundity within the family. The middle maturation stage was absent throughout the year, probably due to the different habitat uses during their life history. Reproductive biology might influence other biological aspects, such as migration and behaviour in the fish. Full article

(This article belongs to the Special Issue The Ecology of Reef Fishes)

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15 pages, 2668 KB

Open AccessArticle

WSSV Infection in the Gut Microbiota of the Black Tiger Shrimp Penaeus monodon

by Youhong Wang, Xiaolu Wang, Chunlei Gai, Yuanyuan Li, La Xu, Shuxian Wang, Li Li, Xiaoqing Yu, Ranghui Fu, Jing Diao, Haibin Ye, Ying Fan and Haipeng Cao

Fishes 2025, 10(9), 440; https://doi.org/10.3390/fishes10090440 - 3 Sep 2025

Viewed by 384

Abstract

This study investigated the impacts of white spot syndrome virus (WSSV) on the gut microbiota of Penaeus monodon through a comparative microbiota analysis of infected and healthy shrimp using 16S rDNA sequencing. The WSSV-infected shrimp exhibited characteristic white spots, reduced feeding activity, and [...] Read more.

This study investigated the impacts of white spot syndrome virus (WSSV) on the gut microbiota of Penaeus monodon through a comparative microbiota analysis of infected and healthy shrimp using 16S rDNA sequencing. The WSSV-infected shrimp exhibited characteristic white spots, reduced feeding activity, and behavioral lethargy preceding 100% mortality. The comparative microbiota analysis revealed a significantly diminished α-diversity in the infected specimens, marked by phylum-level dominance shifts from Proteobacteria (72.68%) and Firmicutes (11.27%) in the controls to Cyanobacteria (75.51%) and Proteobacteria (15.63%) in the WSSV-infected shrimp. An LEfSe analysis identified Arthrospira_PCC-7345 and Halochromatium as significantly enriched taxa during infection, contrasting with depleted populations of Ruegeria, Marivita, Bacillus, and seven other genera. The distinct dysbiosis pattern characterized by the pathogen-favored taxa proliferation and commensal species suppression demonstrates WSSV-associated microbiota restructuring, potentially contributing to disease progression in farmed P. monodon. These findings establish intestinal microbial biomarkers for early WSSV detection in aquaculture systems. Full article

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

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14 pages, 968 KB

Open AccessArticle

Detection of Photobacterium damselae Using Sandwich ELISA with Two Anti-Outer Membrane Protein Antibodies

by Zihao Chen, Wenshu Huang, Qiuhua Yang and Songlin Guo

Fishes 2025, 10(9), 439; https://doi.org/10.3390/fishes10090439 - 2 Sep 2025

Viewed by 287

Abstract

This study developed a dual-antibody sandwich ELISA detection method for Photobacterium damselae, an important pathogen in aquaculture, based on two outer membrane proteins of outer membrane protein C (OmpC) and β-barrel assembly machinery A (BamA) from the strain of P. damselae XP11. [...] Read more.

This study developed a dual-antibody sandwich ELISA detection method for Photobacterium damselae, an important pathogen in aquaculture, based on two outer membrane proteins of outer membrane protein C (OmpC) and β-barrel assembly machinery A (BamA) from the strain of P. damselae XP11. By optimizing the reaction concentrations of the capture antibody of rabbit anti-OmpC or anti-BamA and the HRP-labeled detection antibody of rabbit anti-BamA, it was found that using 1.0 μg/mL of rabbit anti-OmpC or 0.9 μg/mL of rabbit anti-BamA as capture antibodies, and 0.90 μg/mL of HRP-labeled rabbit anti-BamA as the detection antibody, could specifically detect different isolates of P. damselae. The detection limit of this method for the supernatant protein of P. damselae disrupted by ultrasound was 0.2 μg/mL. Repeatability tests showed that the coefficient of variation for detecting 25 strains of bacteria was below 9.1%. Compared with the OmpC-BamA sandwich ELISA detection method, the BamA–BamA combination exhibited better specificity. The results of this study provide an important reference for the rapid detection of P. damselae and other bacterial pathogens in aquaculture. Full article

(This article belongs to the Special Issue Fish Pathogens and Vaccines in Aquaculture)

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14 pages, 2327 KB

Open AccessArticle

Sex-Associated Indels and Candidate Gene Identification in Fujian Oyster (Magallana angulata)

by Yi Han, Yue Ning, Ling Li, Qijuan Wan, Shuqiong Li, Ying Yao, Chaonan Tang, Qisheng Wu, Xiang Guo, Jianfei Qi, Yizhou Ke, Hui Ge and Mingyi Cai

Fishes 2025, 10(9), 438; https://doi.org/10.3390/fishes10090438 - 2 Sep 2025

Viewed by 648

Abstract

Sex determination is a fundamental biological process governing animal reproduction. Although substantial progress has been made in elucidating its genetic basis, the genetic architecture underlying complex sex determination systems remains poorly understood. In this study, we identify sex-associated insertion–deletion (indel) variants, screen candidate [...] Read more.

Sex determination is a fundamental biological process governing animal reproduction. Although substantial progress has been made in elucidating its genetic basis, the genetic architecture underlying complex sex determination systems remains poorly understood. In this study, we identify sex-associated insertion–deletion (indel) variants, screen candidate genes, and compare sex-associated variation across populations with different genetic backgrounds in the Fujian oyster (Magallana angulata). Based on whole-genome resequencing data of a culture strain (designated FL), a total of 299,774 high-quality indels were identified. By integrating genome-wide association analysis (GWAS), fixation index (F_ST) analysis, and sex-biased genotype frequency comparisons, 77 overlapping sex-associated indels were identified, predominantly clustered within a 1.8 Mb (8.3–10.1 Mb) region on chromosome 9. Principal component analysis (PCA) based on the sex-associated markers and their subsets consistently separated male and female individuals in the FL strain. For two representative sex-associated indels, PCR-based genotyping methods were developed and validated. Functional annotation identified putative candidate genes for sex determination, including PKD1L1, 5-HTRL, SCP, and CCKRa. Comparative analysis of variants within PKD1L1 across wild, farmed, and selectively bred populations revealed a progressive enrichment of male-linked alleles in domesticated and selectively bred groups, particularly in male individuals. This study provides direct evidence that sex in the Fujian oyster is genetically determined and reveals that domestication and artificial selection may drive the emergence of major sex-determining loci, offering important insights into the genetic basis of sex determination in the Fujian oyster, and establishing a theoretical and practical foundation for molecular marker-assisted breeding of monosex lines for this species. Full article

(This article belongs to the Section Genetics and Biotechnology)

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14 pages, 829 KB

Open AccessArticle

Rearing Time–Salinity Synergy in Osmoregulation: Ionic Homeostasis and Textural Enhancement in Adult Freshwater Drums (Aplodinotus grunniens)

by Sharifa Mohamed Miraji, Wanwen Chen, Haibo Wen, Liufu Wang, Wu Jin, Xueyan Ma, Pao Xu and Hao Cheng

Fishes 2025, 10(9), 437; https://doi.org/10.3390/fishes10090437 - 2 Sep 2025

Viewed by 352

Abstract

This study demonstrates that rearing duration (14 and 30 days) and environmental salinity (0, 4, 8, and 12 parts per thousand (ppt) of NaCl) synergistically modulate osmoregulation and muscle texture in adult freshwater drums (Aplodinotus grunniens). Salinity significantly reduced the hepatosomatic [...] Read more.

This study demonstrates that rearing duration (14 and 30 days) and environmental salinity (0, 4, 8, and 12 parts per thousand (ppt) of NaCl) synergistically modulate osmoregulation and muscle texture in adult freshwater drums (Aplodinotus grunniens). Salinity significantly reduced the hepatosomatic index at 30 days (p < 0.05). Furthermore, serum biochemical indices were markedly affected. Higher salinity and prolonged rearing time decreased triglycerides, total cholesterol, and low-density lipoprotein (LDL), while high-density lipoprotein (HDL) levels increased at 14 days (p < 0.05), indicating improved lipid metabolism efficiency. Crucially, osmotic pressure remained stable across salinities at 14 days but exhibited a dose-dependent increase at 30 days (p < 0.05), driven primarily by elevated Na⁺ and Cl⁻ concentrations. Salinity (8–12 ppt) markedly enhanced water-holding capacity, reducing cooking loss (~58%), centrifugal loss (~74%), drip loss (~83%), and thaw loss (~84%) versus 0 ppt controls (p < 0.05). Concurrently, key texture parameters also significantly improved, as reflected by hardness, chewiness, resilience, and gumminess. These enhancements might be attributed to hyperosmotic stress-induced cellular dehydration and ionic strength-mediated protein cross-linking. Full article

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18 pages, 14389 KB

Open AccessArticle

Mechanisms of Laurel (Laurus nobilis) Essential Oil on Oxidative Stress and Apoptosis in Hybrid Grouper (Epinephelus fuscoguttatus♀ × Epinephelus lanceolatus♂) During Keep Live Transport

by Ming Yuan, Jingjing Wang, Jun Mei and Jing Xie

Fishes 2025, 10(9), 436; https://doi.org/10.3390/fishes10090436 - 2 Sep 2025

Viewed by 234

Abstract

Anesthesia has emerged as a critical strategy for maintaining fish viability during transport, with natural anesthetics gaining increasing attention in recent research. The active ingredients in Laurus nobilis L. have antioxidant effects and reduce cell apoptosis. Studies have shown that they can upregulate [...] Read more.

Anesthesia has emerged as a critical strategy for maintaining fish viability during transport, with natural anesthetics gaining increasing attention in recent research. The active ingredients in Laurus nobilis L. have antioxidant effects and reduce cell apoptosis. Studies have shown that they can upregulate expression of Nrf2 in mitochondrial biosynthetic factors. This study aimed to investigate the effects of laurel (Laurus nobilis) essential oil on oxidative stress and apoptosis mechanisms during the live transport of hybrid grouper (Epinephelus fuscoguttatus♀ × E. lanceolatus♂). The addition of laurel essential oil during transport activated the Nrf2-Keap1 antioxidant pathway, resulting in up-regulated expression of catalase (cat) and superoxide dismutase (sod) genes. This led to increased enzymatic activity and reduced levels of oxidative stress markers. The mitigation of oxidative stress contributed to physiological stability by downregulating apoptotic gene expression (Bax, Caspase 8), reducing gill and liver tissue damage, and lowering the activity of hepatocyte damage markers aspartate aminotransferase (AST) and alanine aminotransferase (ALT). Metabolomic analysis revealed several key metabolic pathways affected during transport, with the FoxO signaling pathway demonstrating the most significant impact. Within this pathway, reduced glutamate levels appeared to inhibit apoptosis, while decreased ADP and AMP levels potentially influenced antioxidant capacity. The addition of laurel essential oil to transport water proved beneficial in reducing biochemical markers of stress responses in hybrid grouper during keep live transport. Full article

(This article belongs to the Special Issue Use of Essential Oils in Aquaculture)

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16 pages, 1914 KB

Open AccessArticle

Conceptual Design of the Intelligent Electronic Monitoring and Reporting Model for Combating Global Illegal, Unreported, and Unregulated Fishing

by Sung-su Lim and Bong-kyu Jung

Fishes 2025, 10(9), 435; https://doi.org/10.3390/fishes10090435 - 2 Sep 2025

Viewed by 284

Abstract

Preventing illegal, unreported, and unregulated (IUU) fishing—which depletes fishery resources—is a critical task in international fisheries governance. Many countries operate vessel monitoring systems (VMS) and electronic reporting systems (ERS) to track their fishing vessels, while regional fisheries management organizations (RFMOs) are actively considering [...] Read more.

Preventing illegal, unreported, and unregulated (IUU) fishing—which depletes fishery resources—is a critical task in international fisheries governance. Many countries operate vessel monitoring systems (VMS) and electronic reporting systems (ERS) to track their fishing vessels, while regional fisheries management organizations (RFMOs) are actively considering the adoption of electronic monitoring systems (EMS). Although ERS and EMS share the same operational goals, differences in their concepts and functions lead to technical and institutional limitations when implemented separately. This study presents a conceptual design of an intelligent electronic monitoring and reporting (I-EMR) system model, which integrates the strengths of both systems to address these limitations and provides a framework for efficient operation. The necessity for the prompt and proactive adoption of such systems is reinforced by recent analyses of global IUU fishing trends, which indicate that IUU activities are not decreasing despite existing monitoring efforts. While empirical validation is beyond the scope of this study, the conceptual framework aims to support transparent management of fishery resources, facilitate real-time monitoring of fishing activities, and serve as a foundation for future pilot testing and operational deployment. Full article

(This article belongs to the Special Issue Fisheries Monitoring and Management)

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4 pages, 197 KB

Open AccessEditorial

Genetic and Molecular Approaches for Breeding Improvement in Aquaculture

by Xidong Mu

Fishes 2025, 10(9), 434; https://doi.org/10.3390/fishes10090434 - 2 Sep 2025

Viewed by 320

Abstract

Aquaculture has become an increasingly vital sector for global food security, contributing significantly to the supply of high-quality, sustainable animal protein [...] Full article

(This article belongs to the Special Issue Genetics and Breeding in Aquaculture)

18 pages, 1976 KB

Open AccessArticle

Diversity Analysis of Microbial Communities in Shrimp Polyculture Ponds in Coastal Saline–Alkali Regions of Hebei, China

by Enhui Suo, Zhao Chen, Huan Gao, Shijia Yuan and Zhiqiang Chang

Fishes 2025, 10(9), 433; https://doi.org/10.3390/fishes10090433 - 2 Sep 2025

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Abstract

To investigate the structure and successional dynamics of microbial communities in shrimp culture ponds in coastal saline–alkali regions of Hebei, China, we compared the water microbiota of Litopenaeus vannamei monoculture ponds and L. vannamei–Macrobrachium rosenbergii polyculture ponds in the early, mid, [...] Read more.

To investigate the structure and successional dynamics of microbial communities in shrimp culture ponds in coastal saline–alkali regions of Hebei, China, we compared the water microbiota of Litopenaeus vannamei monoculture ponds and L. vannamei–Macrobrachium rosenbergii polyculture ponds in the early, mid, and late culture stages. The results revealed clear temporal succession patterns in both the diversity and composition of microeukaryotic and bacterial communities. Distinct differences were also observed between the two culture models. Compared with monoculture, polyculture ponds showed 2.23–34.76% lower abundances of parasitic microeukaryotes, such as Rozellomycota and Perkinsida. In contrast, the abundances of carbon- and nitrogen-cycling bacterial groups (e.g., LD29, CL500-29_marine_group) and Chlorophyta were 0.24–50.94% higher in the polyculture system. Co-occurrence network analysis showed that polyculture enhanced competitive interactions and increased the network structural complexity within bacterial and cross-domain microbial networks. These findings help elucidate the mechanisms underlying efficient shrimp production in saline–alkali ponds and support the optimization of aquaculture models. Full article

(This article belongs to the Section Sustainable Aquaculture)

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12 pages, 1116 KB

Open AccessArticle

Physiological Effects of Suspended Solids on Venerupis philippinarum and Argopecten irradians

by Ha-Jeong Son, Ju-Won Kim, Min-Young Sohn, Chae-yeong Ji, Su Bhin Jeong, In Gu Kim, Jung-Ha Kang, Hee Jeong Kong, Chan-Il Park and Gyoungsik Kang

Fishes 2025, 10(9), 432; https://doi.org/10.3390/fishes10090432 - 2 Sep 2025

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Abstract

Suspended solids are small particles transported in the water column, which can damage marine ecosystems and impair the health of aquatic organisms. This study evaluated the physiological responses of clams (Venerupis philippinarum) and Atlantic Bay scallops (Argopecten irradians) to [...] Read more.

Suspended solids are small particles transported in the water column, which can damage marine ecosystems and impair the health of aquatic organisms. This study evaluated the physiological responses of clams (Venerupis philippinarum) and Atlantic Bay scallops (Argopecten irradians) to suspended solid exposure. Four concentrations (100–1000 mg/L) were tested, with a control group maintained at 0 mg/L. At each time point (1, 2, 4, 6, 8, and 12 days), hemolymph samples were collected from five individuals per group to measure GOT, GPT, ALP, and cortisol. Exposure to suspended solids significantly increased these biochemical indicators compared with the control. Quantitative survival analysis showed that Venerupis philippinarum survival declined to 83.3% (25/30) at 500 mg/L and 76.7% (23/30) at 1000 mg/L after 5 days, while the control maintained 100% survival. In Argopecten irradians, survival remained close to 100% in most treatments, with a slight reduction to 83.3% (25/30) at 1000 mg/L. No mortality occurred in the control group without suspended solids, whereas mortality was evident under combined temperature stress and suspended solid exposure. These findings demonstrate that suspended solids induce stress responses in both species, with early mortality in Venerupis philippinarum likely caused by particle adhesion to the gills, leading to reduced respiratory efficiency. Full article

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

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20 pages, 6348 KB

Open AccessFeature PaperArticle

Biodiversity Assessment of the Ancient Submerged Port of Egnazia (Southern Adriatic Sea, Mediterranean Sea): New Evidence for Conservation

by Valentina Basile, Marcello Mezzasalma, Federica Talarico, Mauro Francesco La Russa and Elvira Brunelli

Fishes 2025, 10(9), 431; https://doi.org/10.3390/fishes10090431 - 2 Sep 2025

Viewed by 268

Abstract

In addition to their historical relevance, underwater sites of cultural heritage (e.g., shipwrecks, archeological sites) represent secondary habitats for marine life. However, despite a growing interest in their ecological role, studies focusing on these artificial environments remain limited. In this study, we performed [...] Read more.

In addition to their historical relevance, underwater sites of cultural heritage (e.g., shipwrecks, archeological sites) represent secondary habitats for marine life. However, despite a growing interest in their ecological role, studies focusing on these artificial environments remain limited. In this study, we performed the first systematic assessment of the marine biodiversity associated with the submerged structures of the ancient roman port of Egnazia. In particular, we conducted a seasonal (summer 2022 and winter 2023) comparative analysis of the qualitative and quantitative variations in the observed nektonic and benthic taxa between the submerged piers and two surrounding control areas. For benthopelagic and vagile benthic taxa, two seasonal samplings with four transects (of 10 m × 4 m) and three replicates per transect were conducted to analyze taxon diversity, abundance, and variability of individual size. The photo-quadrat method was employed to characterize sessile benthic taxa, using PVC frames measuring 40 cm × 40 cm, randomly placed on the study substrates with 20 replicates for each pier and the two controls. Our results highlight the occurrence of 75 taxa (67 associated with the submerged piers and 63 with the surrounding control areas), including 17 benthopelagic species, 26 vagile benthic and 32 sessile benthic taxa. Overall, our findings highlight that the submerged ancient structures of Egnazia represent a stable and functional marine habitat, promoting an increase in the local biodiversity and abundance of individuals of different species. Full article

(This article belongs to the Section Biology and Ecology)

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22 pages, 5517 KB

Open AccessArticle

Comparing eDNA Metabarcoding and Morphological Surveys Reveals Distinct Fish Community Patterns in the Gaya River

by Jingwen Xu, Weishuai Li, Qihang Gao and Mi Wang

Fishes 2025, 10(9), 430; https://doi.org/10.3390/fishes10090430 - 1 Sep 2025

Viewed by 323

Abstract

Assessing fish biodiversity is essential for freshwater ecosystem conservation. This study compares environmental DNA (eDNA) metabarcoding and traditional morphological surveys to investigate fish communities in the Gaya River, China. A total of 42 fish species were identified, with 13 detected only by eDNA, [...] Read more.

Assessing fish biodiversity is essential for freshwater ecosystem conservation. This study compares environmental DNA (eDNA) metabarcoding and traditional morphological surveys to investigate fish communities in the Gaya River, China. A total of 42 fish species were identified, with 13 detected only by eDNA, 7 exclusively by morphology, and 11 by both methods. A comparative analysis of species composition, functional diversity, and phylogenetic diversity revealed significant differences between the two approaches. Notably, eDNA data indicated higher phylogenetic diversity (PD), while morphological surveys captured greater functional evenness (FEve). Multivariate analyses indicated that total phosphorus (TP), total suspended solids (TSS), electrical conductivity (EC), temperature (T), and pH significantly influenced fish community composition, while dissolved oxygen (DO) was a key driver of species richness (SR), functional richness (FRic), and PD. These findings highlight the methodological differences and complementary strengths of eDNA and morphological approaches in biodiversity assessments. By providing comparative insights into fish diversity patterns, this study underscores the importance of using multi-method approaches to improve freshwater biodiversity monitoring and conservation strategies. Full article

(This article belongs to the Section Biology and Ecology)

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18 pages, 5307 KB

Open AccessArticle

Mechanical Characterization and Dual-Layer Discrete Element Modeling of Mactra veneriformis

by Bin Xu, Yazhou Yang, Hangqi Li, Guangcong Chen, Yizhi Chang, Feihong Guo, Hao Wu, Jixuan Zhao, Zijing Liu, Guochen Zhang, Xiuchen Li, Hanbing Zhang, Qian Zhang and Gang Mu

Fishes 2025, 10(9), 429; https://doi.org/10.3390/fishes10090429 - 1 Sep 2025

Viewed by 354

Abstract

The discrete element model of Mactra veneriformis currently employs an oversimplified multi-sphere approach using EDEM’s Hertz–Mindlin model, assuming uniform shell–flesh mechanical properties. This study developed an advanced dual-layer flexible bonding model through comprehensive biomechanical testing. Mechanical properties and shell morphology were experimentally characterized [...] Read more.

The discrete element model of Mactra veneriformis currently employs an oversimplified multi-sphere approach using EDEM’s Hertz–Mindlin model, assuming uniform shell–flesh mechanical properties. This study developed an advanced dual-layer flexible bonding model through comprehensive biomechanical testing. Mechanical properties and shell morphology were experimentally characterized to inform model development. Parameter optimization combined free-fall experiments with Plackett–Burman screening, steepest ascent method, and Box–Behnken RSM, yielding optimal contact parameters: flesh–flesh stiffness (X₁) = 3.64 × 10¹¹ N/m³, shell–flesh interface (X₃) = 1.48×10¹³ N/m³, shell–shell tangential stiffness (X₆) = 3.23 × 10¹² N/m³, and normal strength (X₇) = 8.35 × 10⁶ Pa. Validation showed only 4.89% deviation between simulated and actual drop tests, with hydraulic impact tests confirming excellent model accuracy. The developed model accurately predicts mechanical behavior and shell fracture patterns during harvesting operations. This research provides a validated numerical tool for optimizing clam cultivation and harvesting equipment design, offering significant potential to reduce shell damage while improving harvesting efficiency in bivalve aquaculture systems. Full article

(This article belongs to the Section Aquatic Invertebrates)

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