Fishes

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

Viewed by 257

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)

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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

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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)

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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

Viewed by 191

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)

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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

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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)

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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

Viewed by 352

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)

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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

Viewed by 366

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)

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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

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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)

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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

Viewed by 223

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)

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31 pages, 659 KB

Open AccessReview

Feed Sources for Sustainable Aquaculture: Black Soldier Fly Larvae (BSFL)

by Lenuța Dîrvariu, Cristian-Alin Barbacariu, Marian Burducea and Daniel Simeanu

Fishes 2025, 10(9), 464; https://doi.org/10.3390/fishes10090464 - 17 Sep 2025

Viewed by 566

Abstract

As global aquaculture is on the rise, the demand for sustainable and high-quality feed ingredients is intensifying. Black soldier fly larvae (BSFL) meal has emerged as a promising alternative to traditional fishmeal due to its favorable nutritional profile, waste recycling potential, and low [...] Read more.

As global aquaculture is on the rise, the demand for sustainable and high-quality feed ingredients is intensifying. Black soldier fly larvae (BSFL) meal has emerged as a promising alternative to traditional fishmeal due to its favorable nutritional profile, waste recycling potential, and low environmental impact. This review explores the novel role of BSF meal in aquafeeds, highlighting its effects on fish growth performance, feed efficiency, and fillet quality. Furthermore, the antimicrobial and immune-boosting properties of lauric acid and chitin are discussed. However, despite its promise, several challenges still hinder the large-scale adoption of BSFL meal in aquaculture. These include regulatory restrictions on substrates, concerns over fish meat quality and safety, consumer acceptance, and the economic and logistical hurdles of industrial-scale BSFL farming. This paper synthesizes current scientific findings and regulatory frameworks, identifies key gaps in knowledge, and discusses the potential of BSFL meal as a sustainable alternative in aquafeeds while addressing its challenges. Full article

(This article belongs to the Section Nutrition and Feeding)

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19 pages, 2558 KB

Open AccessArticle

Small-Scale Fisheries Are Predominant Among Human Factors Influencing Cuban Coral Reefs

by Tamara Figueredo-Martín, Fabián Pina-Amargós, Consuelo Aguilar-Betancourt, Gaspar González-Sansón, Leonardo Espinosa-Pantoja, Dorka Cobián-Rojas, Joan I. Hernández-Albernas, Ariandy González-Gonsález, Yandy Rodríguez Cueto, Kendra Anne Karr, Julia Grace Mason, Kristin Kleisner and Valerie Miller

Fishes 2025, 10(9), 463; https://doi.org/10.3390/fishes10090463 - 17 Sep 2025

Viewed by 383

Abstract

Coral reefs provide environmental goods and services that support biodiversity and people but face diverse threats. To assess the human factors that might be influencing the status of Cuban coral reefs, we collected and analyzed data from three sources: observations made on a [...] Read more.

Coral reefs provide environmental goods and services that support biodiversity and people but face diverse threats. To assess the human factors that might be influencing the status of Cuban coral reefs, we collected and analyzed data from three sources: observations made on a research cruise that circumnavigated Cuba’s waters, expert knowledge, and updated published information. Our results show that small-scale fisheries are predominant among human factors influencing Cuban coral reefs, with more than 97% of the fishing incidents detected in situ during the expedition. Many Cuban reefs are heavily fished, have low levels of contamination, and enjoy high legal protection but experience inadequate enforcement. Tourism occurs on many reefs but could be sustainably increased based on its role in supporting enforcement and compliance and reducing fishing pressure. Densities of marine debris were generally lower in Cuban waters than other Caribbean locations and even lower within protected areas. Many human factors are likely acting synergistically, making management a challenge. This is the first at-sea comprehensive visual survey of human factors in Cuban waters and evaluation of marine debris on Cuba’s reefs, establishing a baseline for future assessments. These findings highlight potential human impacts that must be addressed to safeguard the health of Cuba’s marine ecosystem. Full article

(This article belongs to the Special Issue Sustainable Management of Small-Scale and Data-Limited Fisheries: Diagnosis and Strategies)

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10 pages, 268 KB

Open AccessArticle

Processed Chlorella vulgaris: Effects on Digestibility and Growth Performance in Nile Tilapia (Oreochromis niloticus)

by Pedro Henrique Sessegolo Ferzola, Moritz Meyer and Martin Gierus

Fishes 2025, 10(9), 462; https://doi.org/10.3390/fishes10090462 - 16 Sep 2025

Viewed by 312

Abstract

Microalgae are a promising feed ingredient in aquaculture due to their high nutrient content. This study evaluated the effects of different processing methods of Chlorella vulgaris on digestibility, retention, and growth performance in Nile tilapia (Oreochromis niloticus). A total of 270 [...] Read more.

Microalgae are a promising feed ingredient in aquaculture due to their high nutrient content. This study evaluated the effects of different processing methods of Chlorella vulgaris on digestibility, retention, and growth performance in Nile tilapia (Oreochromis niloticus). A total of 270 mixed-sex tilapia (average weight: 2.8 ± 0.15 g) were randomly assigned and fed to one of three experimental diets—a basal diet, a diet containing freeze-dried Chlorella, or a diet containing spray-dried Chlorella—with three replicates each for 5 weeks. Results indicated that spray-dried Chlorella significantly enhanced protein and energy digestibility, nutrient retention, and growth performance compared to freeze-dried Chlorella. These findings underscore the critical role of processing methods in maximizing the nutritional potential of microalgae for aquaculture feeds. Further research is recommended to optimize processing techniques and inclusion levels for cost-effective and sustainable applications. Full article

(This article belongs to the Section Nutrition and Feeding)

20 pages, 1418 KB

Open AccessArticle

Refining Larval Culture Protocols of Clownfish (Amphiprion ocellaris) to Reduce the Use of Live Feeds

by Casey A. Murray, Brittney D. Lacy, Olivia I. Markham and Matthew A. DiMaggio

Fishes 2025, 10(9), 461; https://doi.org/10.3390/fishes10090461 - 13 Sep 2025

Viewed by 414

Abstract

Clownfish (Amphiprion ocellaris) are a staple commodity in the marine aquarium trade and an emerging model organism for research. Bottlenecks during larviculture affect the survival of juvenile fish and continued reliance on live feeds, such as rotifers (Brachionus spp.) and [...] Read more.

Clownfish (Amphiprion ocellaris) are a staple commodity in the marine aquarium trade and an emerging model organism for research. Bottlenecks during larviculture affect the survival of juvenile fish and continued reliance on live feeds, such as rotifers (Brachionus spp.) and Artemia spp. nauplii, increasing the complexity and cost of raising this species. This study utilized known digestive physiology of clownfish larvae to experimentally reduce the use of live feeds. First, larvae were weaned from rotifers to Artemia at three time points (3, 5, and 7 days post-hatch [DPH]), demonstrating that larvae can be transitioned to Artemia as early as 5 DPH without negative impacts on survival, total length (TL), or whole-body cortisol. A second weaning trial tested the introduction of a commercial microdiet (MD) at 5, 8, and 11 DPH. Survival was greatest when the MD was introduced at 5 DPH (mean ± SD; 64.47 ± 0.10%), and no differences in TL nor whole-body cortisol were detected, suggesting that Artemia may not be required prior to MD weaning. Next, three commercially available MDs were tested for their effects on survival, growth, and coloration of clownfish larvae. Survival and growth did not differ among diets, but fish fed TDO Chroma Boost™ exhibited significantly red-shifted hues, higher saturation, and greater brightness scores in some body regions compared to fish fed Golden Pearl or GEMMA Micro 300. A partial budget analysis indicated a net profit increase of ~$1.60 per fish, highlighting the potential for cost savings and streamlined clownfish production. Full article

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

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19 pages, 2165 KB

Open AccessArticle

Structural Analysis of Acidic Glycosphingolipids in the Adductor Muscle of the Japanese Giant Scallop (Patinopecten yessoensis)

by Shunsuke Sonoda, Saki Itonori, Mutsumi Sugita, Ayako Higashino, Koki Sugimoto, Ryota Hosomi and Kenji Fukunaga

Fishes 2025, 10(9), 460; https://doi.org/10.3390/fishes10090460 - 12 Sep 2025

Viewed by 317

Abstract

Structural analysis of glycosphingolipids provides novel insights into organismal classification and reveals conserved functional roles that transcend taxonomic boundaries. To elucidate the structural characteristics of acidic glycosphingolipids (AGLs) in the adductor muscle of the Japanese giant scallop (Patinopecten yessoensis), AGLs were [...] Read more.

Structural analysis of glycosphingolipids provides novel insights into organismal classification and reveals conserved functional roles that transcend taxonomic boundaries. To elucidate the structural characteristics of acidic glycosphingolipids (AGLs) in the adductor muscle of the Japanese giant scallop (Patinopecten yessoensis), AGLs were isolated and purified by column chromatography using anion exchange resin and silica gel. Structural characterization was performed using mass spectrometry, proton nuclear magnetic resonance spectroscopy, and immunological techniques. The sugar chain structure was identified as GlcA4Meβ1-4(GalNAc3Meα1-3)Fucα1-4GlcNAcβ1-2Manα1-3Manβ1-4Glcβ1-Cer, consistent with the mollu-series core reported for mollusks. In addition to uronic acid, the structure was distinguished by internal fucose and methylated sugars, features commonly found in bivalves. The presence of xylose in the sugar chains of AGLs was also suggested. In contrast, the ceramide moiety was composed primarily of fatty acids C16:0 and C18:0 and the long-chain base d16:1. This chemical structure provides valuable insights into the biological classification of P. yessoensis and the mollu-series glycolipids containing fucose and methylated sugars, which may serve as bioactive components shared across species in the phylum Mollusca and class Bivalvia. Full article

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11 pages, 1569 KB

Open AccessArticle

Movements of Galapagos Sharks (Carcharhinus galapagensis) in Eastern Tropical Pacific Waters off Central and South America

by Bradley M. Wetherbee, Guy M.C. Harvey, Colby D. Kresge, Mary K. Brantley, Owen W. Fleischer, Nicole A. Kobasa, Jeremy J. Vaudo and Mahmood S. Shivji

Fishes 2025, 10(9), 459; https://doi.org/10.3390/fishes10090459 - 12 Sep 2025

Viewed by 845

Abstract

Galapagos sharks (Carcharhinus galapagensis) are a large species belonging to the family Carcharhinidae, with poorly understood biology, especially along continental coastlines, which limits effective management of their populations. Here, we report preliminary findings of their movements along the Pacific Coast of [...] Read more.

Galapagos sharks (Carcharhinus galapagensis) are a large species belonging to the family Carcharhinidae, with poorly understood biology, especially along continental coastlines, which limits effective management of their populations. Here, we report preliminary findings of their movements along the Pacific Coast of Panama and Colombia, derived from satellite telemetry. Sharks were tracked for as long as 1.5 years, during which they moved extensively (~400 km along the Panama/Colombia coastline), with areas with high concentrations of detections that spanned the Panama/Colombia border. Sharks appeared to alter their movements during the diel cycle (more detections at night) and in relation to the wet/dry seasons (more detections during the dry season). Locations of shark detections were most commonly within 20 km of shore and in water less than 100 m deep, although detections were recorded hundreds of kilometers from shore in water thousands of meters deep. Galapagos sharks appear to move more extensively along continental coastlines compared to island locations, where most previous information about their movements and biology has been obtained. Full article

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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

Viewed by 348

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)

20 pages, 618 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 651

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

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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

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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

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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

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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

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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 401

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 386

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

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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 435

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

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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

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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 392

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

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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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