Fishes

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 (registering DOI) - 12 Sep 2025

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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)

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