Fishes

13 pages, 5120 KiB

Open AccessArticle

Hepcidin Deficiency Disrupts Iron Homeostasis and Induces Ferroptosis in Zebrafish Liver

by Mingli Liu, Mingjian Peng, Jingwen Ma, Ruiqin Hu, Qianghua Xu, Peng Hu and Liangbiao Chen

Fishes 2025, 10(5), 243; https://doi.org/10.3390/fishes10050243 - 21 May 2025

Viewed by 128

Abstract

Hepcidin is a key regulator of systemic iron homeostasis, which is essential for maintaining iron balance and cellular health. To investigate its role in zebrafish, we empolyed a hepcidin knockout model. Morphological and histological analyses revealed pale livers and significant iron accumulation in [...] Read more.

Hepcidin is a key regulator of systemic iron homeostasis, which is essential for maintaining iron balance and cellular health. To investigate its role in zebrafish, we empolyed a hepcidin knockout model. Morphological and histological analyses revealed pale livers and significant iron accumulation in hep^−/− zebrafish, particularly in liver, skin, and egg tissues. RNA sequencing identified 1,424 differentially expressed genes (DEGs) between wild-type (WT) and hep^−/− zebrafish, with significant enrichment in pathways related to ferroptosis, fatty acid degradation, and heme binding. Western blot analysis showed reduced levels of key iron-related proteins, including GPX4, Fth1, and ferroportin (FPN), indicating impaired iron transport and increased oxidative stress. Gene Ontology (GO) and KEGG analyses highlighted disruptions in iron metabolism and lipid oxidation, linking iron overload to ferroptosis in the absence of hepcidin. These findings demonstrate that hepcidin deficiency leads to profound dysregulation of iron homeostasis, driving lipid peroxidation and ferroptosis in the zebrafish liver. Our study provides mechanistic insights into the molecular consequences of hepcidin loss, advancing our understanding of iron-related oxidative damage and its physiological impacts. Full article

(This article belongs to the Special Issue Genomics Applied to Fish Health)

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23 pages, 1943 KiB

Open AccessArticle

Effects of Social Enrichment Induced by Different-Sized Groups and Live Bait on Growth, Aggressive Behavior, Physiology, and Neurogenesis in Juvenile Sebastes schlegelii

by Zhen Zhang, Xiaoming Yu, Zhongxin Wu and Tao Tian

Fishes 2025, 10(5), 242; https://doi.org/10.3390/fishes10050242 - 21 May 2025

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Abstract

This study examined the effects of stress and social enrichment on fish neuroplasticity and antioxidant capacity, addressing growing concerns about fish welfare in aquaculture. A 2 × 2 × 2 factorial design comprising eight treatment groups was implemented to investigate how bait type, [...] Read more.

This study examined the effects of stress and social enrichment on fish neuroplasticity and antioxidant capacity, addressing growing concerns about fish welfare in aquaculture. A 2 × 2 × 2 factorial design comprising eight treatment groups was implemented to investigate how bait type, group size (two distinct sizes tested), and stress level affected the expression of neurogenesis-related genes (PCNA, DCX, and NeuroD) and antioxidant parameters (MDA levels, CAT, GSH-Px, and SOD activity) in the fish. The findings demonstrated that social enrichment significantly reduced aggressive behavior and basal cortisol levels and enhanced the expression of neurogenesis-related gene. However, the optimal group-size augmentation (between the two group sizes tested) considerably increased the activity of antioxidant enzymes and decreased MDA levels. Acute stress further upregulated cortisol levels and the expression of genes related to neurogenesis. A scientific foundation for enhancing fish welfare in aquaculture is provided by the study’s confirmation that social enrichment reduces stress and fosters neuroplasticity. Full article

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21 pages, 7821 KiB

Open AccessArticle

Utilizing Environmental DNA for Early Monitoring of Non-Indigenous Fish Species in Maritime Ballast Water

by Hanglei Li, Hui Jia and Hui Zhang

Fishes 2025, 10(5), 241; https://doi.org/10.3390/fishes10050241 - 21 May 2025

Viewed by 129

Abstract

Ballast water has become a significant vector for the global spread of non-indigenous aquatic species. These species may cause severe ecological disruption and economic losses when introduced into new environments. Traditional monitoring techniques often lack the sensitivity and efficiency required for early monitoring, [...] Read more.

Ballast water has become a significant vector for the global spread of non-indigenous aquatic species. These species may cause severe ecological disruption and economic losses when introduced into new environments. Traditional monitoring techniques often lack the sensitivity and efficiency required for early monitoring, hindering timely and effective management. In this study, we used environmental DNA (eDNA) technology to assess fish diversity and identify non-indigenous fish species in ballast water samples collected from 14 international vessels entering Dongjiakou Port, China. Genetic evidence of five non-indigenous fish species was monitored, including two recognized invasive species (Lates calcarifer and Anguilla anguilla). Among all groups, samples from Group B (V2, V3, V6, V8) exhibited the highest diversity of non-indigenous species, suggesting regional differences in species composition that may reflect source port biodiversity. These findings highlight the utility of eDNA-based monitoring not only for early detection of potentially non-indigenous taxa but also for capturing biogeographic patterns associated with global maritime traffic. By demonstrating the effectiveness of this approach at an international port, this study contributes a scientific foundation for both local biodiversity conservation and broader ecological surveillance, offering valuable insights for the ongoing development of ballast water management strategies worldwide. Full article

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

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22 pages, 311 KiB

Open AccessArticle

Utilization of Fish Meal and Fish Oil from Smoked Salmon By-Products in Juvenile Striped Bass (Morone saxatilis) Feeds: Growth Performance, Nutritional Composition, and Shelf-Life Assessment of Upcycled Ingredients

by Connor Neagle, Michael O. Frinsko, Ryan Kelly, Steven G. Hall, Benjamin J. Reading, Alexander Chouljenko, Greg Bolton and Michael Joseph

Fishes 2025, 10(5), 240; https://doi.org/10.3390/fishes10050240 - 21 May 2025

Viewed by 460

Abstract

Fish meal (FM) and fish oil (FO) are vital components commonly used in feed formulations. However, their supply, which generally comes from capture fisheries, is being exhausted, necessitating the exploration of sustainable alternatives. In a two-part study, the first part evaluated the FM [...] Read more.

Fish meal (FM) and fish oil (FO) are vital components commonly used in feed formulations. However, their supply, which generally comes from capture fisheries, is being exhausted, necessitating the exploration of sustainable alternatives. In a two-part study, the first part evaluated the FM and FO derived from smoked salmon by-product (SSBP) over a 12-week accelerated shelf-life test, comparing their lipid oxidation, amino acid, and fatty acid profiles to those of commercial whitefish meal and oil. In the second part, the SSBP FM and FO were then included in three experimental feeds at 25%, 50%, and 100% inclusion levels. These feeds were tested on juvenile striped bass (Morone saxatilis) cultured in a recirculating aquaculture system (RAS). The results indicated that the quality of SSBP FM and FO was lower than the commercial product (less amino acids (23.98% vs. 60.30%) and omega-3 fatty acids (9.46% vs. 26.6%), respectively). SSBP FO exhibited high initial peroxide value (21.00 ± 0.00 meq/kg oil), with gradually increasing total oxidation value and p-Anisidine value during storage. Regarding the feeding trial, all fish showed signs of Mycobacterium marinum infection after one month. While there was no significant difference in feed palatability (p > 0.8559), the feed conversion ratio was less efficient for the 100% SSBP feed (1.44 ± 0.14) compared to commercial feed (1.36 ± 0.13), but these differences were not statistically significant. This study suggests that SSBP FM and FO can be used as supplements at lower levels (25% and 50%) without negatively affecting growth, feed efficiency, or survival. Our findings may be useful for enabling beneficial collaborations between smoked salmon processors, feed manufacturers, and striped bass farmers, therefore contributing to sustainability in aquaculture practices. Full article

(This article belongs to the Special Issue Alternative Feeds for Aquatic Animals)

14 pages, 3085 KiB

Open AccessArticle

Biological Traits and Isoenzymatic Characterization of Triplophysa strauchii from the Turks River

by Gulden Serekbol, Chengxin Wang, Liting Yang, Huanhuan Wang, Jiaxuan Liu, Qiang Huo, Hao Xu, Yong Song, Daoquan Ren and Shengao Chen

Fishes 2025, 10(5), 239; https://doi.org/10.3390/fishes10050239 - 21 May 2025

Viewed by 65

Abstract

The intensification of human activities in recent years has led to significant overexploitation of Triplophysa strauchii populations, resulting in a decline in the species’ natural stocks. This underscores the need for research and development initiatives aimed at supporting the recovery and sustainable management [...] Read more.

The intensification of human activities in recent years has led to significant overexploitation of Triplophysa strauchii populations, resulting in a decline in the species’ natural stocks. This underscores the need for research and development initiatives aimed at supporting the recovery and sustainable management of the species. Therefore, this study investigated its biological traits and isozyme characteristics in detail. First, throutigations of fish ecology, the age and growth patterns of T. strauchii were examined. The results revealed that the length of the otoliths was greater than the width and that the intermajor groove was indistinct. The age range of the fish was 0–4 years. A correlation between body length and weight revealed that T. strauchii exhibited isometric growth patterns. In terms of growth parameters, the inflection point in age for T. strauchii was t_i = 3.23. Additionally, to analyze the enzymes lactate dehydrogenase (LDH), malate dehydrogenase (MDH), and esterase (EST) in ten tissues of T. strauchii (liver, muscle, heart, gills, eye, brain, fins, kidneys, gonads, and intestines), vertical plate electrophoresis was performed via polyacrylamide gels. The results of isoenzyme analysis revealed that the LDHA (lactate dehydrogenase A subunit) gene was predominant in all tissues. A maximum of two s-MDH enzyme bands with three m-MDH enzyme bands were detected, with a classic enzyme profile and no gene mutation. The EST enzyme was highly expressed in the liver and kidney and was less polymorphic. In general, T. strauchii exhibited a spindle-like body shape and isometric growth patterns in the Turks River. It exhibited a narrow age range, strong adaptability, and stable genetic traits. This species has high development potential, utilization value and ecological significance. Full article

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19 pages, 3848 KiB

Open AccessArticle

Assessment of Exploited Stock and Management Implications of Tiger Tooth Croaker (Otolithes ruber) in Coastal Waters of Makran, Pakistan

by Samroz Majeed, S M Nurul Amin, Asad Ullah Ali Muhammad and Sudheer Ahmed

Fishes 2025, 10(5), 238; https://doi.org/10.3390/fishes10050238 - 20 May 2025

Viewed by 823

Abstract

Pakistan’s marine fishing industry is crucial to the country’s economy, generating employment opportunities and foreign revenue. It produces 80% of the country’s total fish production. Otolithes ruber is a commercially important fish on the Makran coast of Pakistan, contributing significantly to the region’s [...] Read more.

Pakistan’s marine fishing industry is crucial to the country’s economy, generating employment opportunities and foreign revenue. It produces 80% of the country’s total fish production. Otolithes ruber is a commercially important fish on the Makran coast of Pakistan, contributing significantly to the region’s croaker fisheries. This study is the first to apply three length-based approaches for assessing the stock status of O. ruber in the Makran coast: (1) TropFishR to estimate the mortality, growth parameters, and current exploitation status, reference points based on the yield per recruitment model, (2) the length-based Bayesian biomass method (LBB) to calculate stock biomass, and (3) the length-based spawning potential ratio (LBSPR) to estimate the spawning potential ratio. The length–weight relationship of Otolithes ruber was a positive allometric pattern (b = 3.28; R² = 0.94). Growth parameters for Otolithes ruber were L_∞ = 55.47 cm, K = 0.50 year⁻¹. The calculated total mortality rate (Z), natural mortality (M), and fishing mortality (F) were 2.27 year⁻¹, 0.67 year⁻¹, and 1.6 year⁻¹, respectively. The exploitation rate (E) was 0.70, indicating severe overexploitation. The current length at first capture (Lc₅₀) = 27.37 cm was lower than that at first maturity (Lm₅₀) = 30.75 cm, indicating growth overfishing. The current spawning potential ratio (8%) was lower than the optimal value (40%), indicating recruitment overfishing. The current biomass, concerning virgin biomass B/B_o, was also 8%, resulting in a 92% stock decline. We recommend reducing the exploitation pressure by limiting the commercial catch to an optimum length range of 34.5–42.2 cm and reducing fishing pressure by 40% to ensure sustainable fishery management. 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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10 pages, 11872 KiB

Open AccessArticle

Citizen Science Illuminates a City-Dwelling Whale: A Report on the Large Aggregation of Narrow-Ridged Finless Porpoises in Tokyo Bay, Japan

by Gen Nakamura and Ayumi Hirose

Fishes 2025, 10(5), 237; https://doi.org/10.3390/fishes10050237 - 19 May 2025

Viewed by 346

Abstract

Tokyo Bay is one of the busiest ocean areas for human activity worldwide, characterized by a high density of maritime traffic and industrial development. This area is also recognized as the habitat of the narrow-ridged finless porpoise, an endangered toothed whale. Although the [...] Read more.

Tokyo Bay is one of the busiest ocean areas for human activity worldwide, characterized by a high density of maritime traffic and industrial development. This area is also recognized as the habitat of the narrow-ridged finless porpoise, an endangered toothed whale. Although the existence of this species has been recognized, its scientific data, such as population size and geographic distribution, are limited in the region. Therefore, using social media, we initiated a research project to collect sighting information on this species in Tokyo Bay. As a result, 27 valid pieces of information on the finless porpoises were collected from July 2024 to the end of February 2025. The sightings were reported mainly in the waters north of Futtsu Cape, indicating that this species is localized in the northern part of Tokyo Bay. Also, most of the reported sightings were of groups of wo or more animals. Notably, a school of at least 30 animals was recorded, marking the most prominent school ever observed in the region and the third largest in Japan. This study highlights the importance of the northern region of Tokyo Bay as a habitat for this species. The effective integration of citizen science with scientific and quantitative research will enhance our understanding of the life history of this endangered species, thereby supporting conservation efforts. Full article

(This article belongs to the Section Biology and Ecology)

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27 pages, 6163 KiB

Open AccessArticle

Aquaculture Areas Extraction Model Using Semantic Segmentation from Remote Sensing Images at the Maowei Sea of Beibu Gulf

by Weirong Qin, Mohd Hasmadi Ismail, Yangyang Luo, Yifeng Yuan, Junlin Deng, Mohammad Firuz Ramli and Ning Wu

Fishes 2025, 10(5), 236; https://doi.org/10.3390/fishes10050236 - 19 May 2025

Viewed by 290

Abstract

The extraction of aquaculture areas from high-resolution remote sensing images is crucial for effective coastal management and resource preservation. This study introduces SwinNet, a semantic segmentation model leveraging multi-scale feature fusion to enhance the extraction of aquaculture areas, particularly in the Maowei Sea [...] Read more.

The extraction of aquaculture areas from high-resolution remote sensing images is crucial for effective coastal management and resource preservation. This study introduces SwinNet, a semantic segmentation model leveraging multi-scale feature fusion to enhance the extraction of aquaculture areas, particularly in the Maowei Sea of the Beibu Gulf, China. Utilizing the Swin Transformer backbone and a novel Parallel Pooling Attention Module (PPAM), SwinNet minimizes background noise and improves segmentation accuracy. SwinNet achieved a pixel accuracy of 96.53% and an intersection over the union of 93.07% on an aquaculture dataset, demonstrating superior performance in overcoming noise and accurately extracting aquaculture areas. SwinNet offers an effective solution for large-scale, high-precision monitoring of coastal aquaculture, with potential broader applicability in aquatic resource conservation and management. Full article

(This article belongs to the Special Issue Machine Learning in Aquaculture)

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22 pages, 5333 KiB

Open AccessReview

A Review of Standardization in Mississippi’s Multidecadal Inland Fisheries Monitoring Program

by Caleb A. Aldridge and Michael E. Colvin

Fishes 2025, 10(5), 235; https://doi.org/10.3390/fishes10050235 - 18 May 2025

Viewed by 258

Abstract

Standardizing data collection, management, and analysis processes can improve the reliability and efficiency of fisheries monitoring programs, yet few studies have examined the operationalization of these tasks within agency settings. We reviewed the Mississippi Department of Wildlife, Fisheries, and Parks, Fisheries Bureau’s inland [...] Read more.

Standardizing data collection, management, and analysis processes can improve the reliability and efficiency of fisheries monitoring programs, yet few studies have examined the operationalization of these tasks within agency settings. We reviewed the Mississippi Department of Wildlife, Fisheries, and Parks, Fisheries Bureau’s inland recreational fisheries monitoring program—a 30+-year effort to standardize field protocols, data handling procedures, and automated analyses through a custom-built computer application, the Fisheries Resources Analysis System (FRAS). Drawing on quantitative summaries of sampling trends and qualitative interviews with fisheries managers, we identified key benefits, challenges, and opportunities associated with the Bureau’s standardization efforts. Standardized procedures improved sampling consistency, data reliability, and operational efficiency, enabling the long-term tracking of fish population and angler metrics across more than 270 managed waterbodies. However, challenges related to analytical transparency and spatiotemporal comparisons persist. Simulations indicated that under current conditions, 5.8, 22.9, and 37.1 years would be required to sample (boat electrofishing) 50%, 75%, and 95% of the Bureau’s waterbodies at least once, respectively; these figures should translate to other agencies, assuming similar resource availability per waterbody. The monitoring program has reduced manual processing effort and enhanced staff capacity for waterbody-specific management, yet several opportunities remain to improve efficiency and utility. These include expanding FRAS functionalities for trend visualization, integrating mobile field data entry to reduce transcription errors, linking monitoring results with management objectives, and enhancing automated report generation for management support. Strengthening these elements could not only streamline workflows but better position agencies to apply standardized data in adaptive management embedded into the monitoring program. Full article

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

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23 pages, 11176 KiB

Open AccessArticle

Multi-Omics Investigation of Fatty Acid Content Variations in Common Carp (Cyprinus carpio) Muscle: Integrating Genome, Transcriptome, and Lipid Profiling Data

by Kaikuo Wang, Qi Wang, Yingjie Chen, Yiming Cao, Ran Zhao, Shuangting Yu, Xiaoqing Sun, Yan Zhang and Jiongtang Li

Fishes 2025, 10(5), 234; https://doi.org/10.3390/fishes10050234 - 16 May 2025

Viewed by 93

Abstract

Fatty acids (FAs), especially the polyunsaturated fatty acids (PUFAs), play pivotal roles in growth and development. Fish possess a remarkable ability to synthesize PUFAs, rendering them a crucial and significant source of these essential FAs for human consumption. Despite extensive research on the [...] Read more.

Fatty acids (FAs), especially the polyunsaturated fatty acids (PUFAs), play pivotal roles in growth and development. Fish possess a remarkable ability to synthesize PUFAs, rendering them a crucial and significant source of these essential FAs for human consumption. Despite extensive research on the metabolic processes of FAs, the primary processes underlying FA content variation and corresponding regulatory mechanisms remain largely unexplored. We quantified the muscular FA profiles of 304 common carp samples. High variation in muscle FA content among samples was observed, with the coefficients of variation ranging from 0.36 to 0.92. With genome-wide association studies (GWAS), we identified 1410 SNPs significantly associated with the FA content. The genetic variation at genes participating in oxidation, ubiquitination, and transcriptional factors was associated with the content of multiple FAs, while few variants were observed in the FA-synthesis genes. For the total PUFA (TPUFA) content, transcriptome analysis of groups with the highest and lowest TPUFA content identified 715 differentially expressed genes (DEGs), including genes involved in oxidation and ubiquitination. Using multiple genomic selection programs with the associated SNPs for FA content, we obtained high and positive correlations ranging from 0.65 to 0.92 between the real FA contents and estimated breeding values. These findings manifested the major-effect processes governing the differences in muscular FA content and their regulatory mechanisms. The optimal genomic selection programs provide novel and feasible perspectives to enhance FA content in common carp. Full article

(This article belongs to the Special Issue Molecular Design Breeding in Aquaculture)

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17 pages, 1680 KiB

Open AccessArticle

Fick’s Diffusion Laws and Scaling of the Gill Surface Area and Oxygen Uptake in Fish

by Daniel Pauly and Johannes Müller

Fishes 2025, 10(5), 233; https://doi.org/10.3390/fishes10050233 - 16 May 2025

Viewed by 141

Abstract

The oxygen consumption of adult fish (Q) is proportional to their body weight (W) raised to a power, estimated as the slope (d_Q) of a linear regression of log(Q) vs. log(W). Similarly, [...] Read more.

The oxygen consumption of adult fish (Q) is proportional to their body weight (W) raised to a power, estimated as the slope (d_Q) of a linear regression of log(Q) vs. log(W). Similarly, the gill surface area of adult fish (GSA) is proportional to W raised to the power d_G, as also estimated via a log-log linear proportional to their surface area. Moreover, because of Fick’s laws of diffusion, d_Q should be at least similar to d_G. Recently, the claim has been made that non-zero differences between d_Q and d_G invalidate the Gill-Oxygen Limitation Theory (GOLT), which suggests that the O₂ supplied by gills growing with d_G <1 limits the growth of older and larger fish. We show here, based on 33 pairs of d_G and d_Q in 33 fish species and other information that (i) while individual differences between d_Q and d_G are observed in several cases, there is no significant overall difference across the 33 estimates and (ii) large differences between d_Q and d_G are primarily due to ontogenetic changes in scaling (OCS), likely ontogenetic changes in gills’ water–blood (or ‘diffusion’) distance and, as well, multiple sources of experimental variability and potential errors, leading to outliers and random differences. Full article

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17 pages, 2781 KiB

Open AccessArticle

Model Selection Applied to Growth of the Stingray Urotrygon chilensis (Günther, 1872) in the Southeastern Mexican Pacific

by Ana Bricia Guzmán-Castellanos, Enrique Morales-Bojórquez, Hugo Aguirre-Villaseñor and Javier Tovar-Ávila

Fishes 2025, 10(5), 232; https://doi.org/10.3390/fishes10050232 - 16 May 2025

Viewed by 95

Abstract

The present study analyzed the growth pattern of the stingray Urotrygon chilensis caught as bycatch by the shrimp fishery in the southeastern Mexican Pacific. From January to December 2012, the thoracic vertebrae of 491 females and 205 males were collected. Female ages ranged [...] Read more.

The present study analyzed the growth pattern of the stingray Urotrygon chilensis caught as bycatch by the shrimp fishery in the southeastern Mexican Pacific. From January to December 2012, the thoracic vertebrae of 491 females and 205 males were collected. Female ages ranged from 0 to 14 years, whereas male ages ranged from 0 to 12 years. The marginal increment and edge analyses suggested the annual formation of growth bands in the vertebrae. The size-at-age data were analyzed using the multimodel inference approach; six candidate growth models were compared, including models with a theoretical age-at-zero total length, mean size-at-birth, and generalized models. Based on Akaike’s information criterion, the best statistical fit to the size-at-age data was the two-phase Gompertz growth model (k = −0.13, G = 1.59,

L_{0}

= 10.40) for males and the two-parameter Gompertz growth model (k = 1.42, α = 0.15,

L_{0}

= 10.90) for females. In this study, we compare the growth parameters among batoid species, finding that U. chilensis has a relatively short lifespan, slower growth, and that females are larger than males. Full article

(This article belongs to the Section Biology and Ecology)

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23 pages, 3600 KiB

Open AccessArticle

The Effect of Ontogenetic Dietary Shifts on the Trophic Structure of Fish Communities Based on the Trophic Spectrum

by Junwei Xu, Jie Yin, Binduo Xu, Chongliang Zhang, Yupeng Ji, Yiping Ren and Ying Xue

Fishes 2025, 10(5), 231; https://doi.org/10.3390/fishes10050231 - 15 May 2025

Viewed by 170

Abstract

The trophic spectrum provides a useful method to investigate the trophic structure of fish communities. However, ontogenetic shifts in diet can cause variations in the trophic level with body size, thereby influencing the trophic structure of fish communities. In this study, we investigated [...] Read more.

The trophic spectrum provides a useful method to investigate the trophic structure of fish communities. However, ontogenetic shifts in diet can cause variations in the trophic level with body size, thereby influencing the trophic structure of fish communities. In this study, we investigated the effect of ontogenetic dietary shifts on the trophic structure of fish communities in Haizhou Bay based on trophic spectra and trophic indicators calculated under different scenarios of functional group classification. The results showed that the size threshold of ontogenetic dietary shifts was a viable basis for functional group classification. The biomass of fishes at trophic levels 3.4–3.8 was lower when ontogenetic dietary shifts were considered, which can influence the intensity of top–down control and hinder the formulation of harvest strategies. Ontogenetic dietary shifts can also redistribute the biomass of fishes across trophic levels, thereby regulating the trophic structure of fish communities. Different responses of trophic indicators to ontogenetic dietary shifts were identified, with high trophic indicator (HTI) being the most appropriate indicator reflecting the effect of ontogenetic dietary shifts in the trophic structure. This study provides a feasible way to optimize the trophic spectrum for elucidating the trophic structure of fish communities. And we recommend that ontogenetic dietary shifts should be considered and valued in fishery management. Full article

(This article belongs to the Special Issue Trophic Ecology of Freshwater and Marine Fish Species)

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42 pages, 5308 KiB

Open AccessArticle

Assessing Diadromous Fish Populations in the Lima River, Northwest Iberian Peninsula

by Luís Pereira, Ulisses Azeiteiro and Carlos Antunes

Fishes 2025, 10(5), 230; https://doi.org/10.3390/fishes10050230 - 15 May 2025

Viewed by 731

Abstract

The Lima River in northern Portugal serves as a vital habitat for diadromous fish species, yet it remains one of the least studied aquatic systems in the region. This study investigates the ecology and biology of key diadromous fish populations, including sea lamprey [...] Read more.

The Lima River in northern Portugal serves as a vital habitat for diadromous fish species, yet it remains one of the least studied aquatic systems in the region. This study investigates the ecology and biology of key diadromous fish populations, including sea lamprey (Petromyzon marinus), shads (Alosa alosa and Alosa fallax), trout (Salmo trutta), and European eel (Anguilla anguilla), during their reproductive migration and riverine periods. A total of 3242 individuals from 15 species were sampled, with native species accounting for 51.1% of the catch. Results revealed significant differences in size and weight of lampreys, with individuals from the Lima River being significantly smaller than those from regional rivers such as the Minho and Mondego. Shad populations showed a high proportion of hybrids (33.8%), suggesting extensive hybridization between A. alosa and A. fallax. Analysis of trout stomach contents revealed a diverse diet dominated by insects (66.9%), crustaceans (6.8%), and fish (6.8%), but also an alarming presence of plastic debris (1.1%), highlighting potential pollution problems. For European eels, this study marks the first record of the invasive swim bladder parasite Anguillicola crassus in the Lima River, with 84.8% of eels sampled showing moderate to severe swim bladder damage. These findings contribute to a deeper understanding of diadromous fish ecology and emphasize the importance of conservation efforts in estuarine systems worldwide. Full article

(This article belongs to the Section Biology and Ecology)

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15 pages, 1909 KiB

Open AccessArticle

Effects of Clozapine, Haloperidol, and the NMDA Antagonist Ketamine on Novel Object Recognition in Gnathonemus petersii: A New Possible Model for Schizophrenia Research

by Petra Horká, Josefina Mavrogeni, Veronika Langová, Pavel Horký, Jan Hubený, Ivana Chrtková, Karel Valeš, Martin Kuchař and Jiří Horáček

Fishes 2025, 10(5), 229; https://doi.org/10.3390/fishes10050229 - 15 May 2025

Viewed by 219

Abstract

In animal models, ketamine, a non-competitive N-methyl-D-aspartate (NMDA) antagonist, induces schizophrenia-like symptoms, such as positive and negative symptoms, as well as cognitive deficits. In the present study, we evaluated the behavioral responses and the number of EODs (electric organ discharges) of the weakly [...] Read more.

In animal models, ketamine, a non-competitive N-methyl-D-aspartate (NMDA) antagonist, induces schizophrenia-like symptoms, such as positive and negative symptoms, as well as cognitive deficits. In the present study, we evaluated the behavioral responses and the number of EODs (electric organ discharges) of the weakly electric fish Gnathonemus petersii using the novel object recognition task (NORT). We aimed to investigate whether pharmacological modulation of the glutamatergic system would impair cognitive functions by administering the NMDA receptor antagonist ketamine, and whether these impairments could be suppressed by the administration of typical (first-generation) and atypical (second-generation) antipsychotics—clozapine and haloperidol, respectively. G. petersii preferred the familiar object over the novel object in the NORT paradigm. Although no significant differences were observed when exploring the two identical objects during the training session, the fish spent less time, moved a shorter distance, and emitted fewer EODs in the testing phase with the novel object. No direct relationship was detected between the EODs and behavioral responses to the administration of ketamine and typical antipsychotics. Ketamine administered with atypical antipsychotic clozapine disrupted the perception of the original object, where one of the objects was preferred. In the novel object trial, the time spent on the original and new objects was attenuated to the same level. Full article

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19 pages, 4354 KiB

Open AccessArticle

Effects of Increased Feeding Rates on Oxidative Stress, Biochemical Indices and Growth of Juvenile Hybrid Grouper (Epinephelus fuscoguttatus ♀ × Epinephelus tukula ♂) Under Mild-Hyperoxia Conditions

by Zhiyi Wang, Yikai Zheng, Dengpan Dong, Xiefa Song and Meng Li

Fishes 2025, 10(5), 228; https://doi.org/10.3390/fishes10050228 - 15 May 2025

Viewed by 218

Abstract

Evaluating the interaction between dissolved oxygen (DO) and feeding rates (FRs) in fish is crucial for the precise regulation of aquaculture water environments. This study established four treatment groups: the CK group (DO = 6 mg/L, FR = 2% of body weight), the [...] Read more.

Evaluating the interaction between dissolved oxygen (DO) and feeding rates (FRs) in fish is crucial for the precise regulation of aquaculture water environments. This study established four treatment groups: the CK group (DO = 6 mg/L, FR = 2% of body weight), the HFR group (DO = 6 mg/L, FR = 3.5% of body weight), the HDO group (DO = 9 mg/L, FR = 2% of body weight), and the MIX group (DO = 6 mg/L, FR = 3.5% of body weight). The combined effects of dissolved oxygen and feeding levels on oxidative stress, biochemical indicators, and growth in the hybrid grouper were evaluated. The results showed that mild hyperoxia significantly upregulates the expression of antioxidant enzyme genes (cat, cu/zn-sod, and gpx1a). Under conditions of mild hyperoxia, an increased feed rate can significantly downregulate the expression of cat and gpx1a. Additionally, serum levels of carnosine and cndp1 in muscle tissue are significantly elevated. Furthermore, a high FR mitigates the downregulation of glucose, triglycerides, and alanine aminotransferase (ALT) induced by mild hyperoxia while alleviating the upregulation of aspartate aminotransferase (AST). The combined effects of mild hyperoxia and high FR significantly enhance final body weight and specific growth rate (SGR), with notable interactions observed. Mild hyperoxia reduces serum levels of bile acids and glycocholic acid under high feeding conditions while significantly downregulating the expression of ghrb in both liver and brain tissues. In summary, high FRs alleviate oxidative stress and energy substrate deficiency in juvenile hybrid grouper under mild-hyperoxia environments. Moreover, the synergistic effect between mild hyperoxia and high FR promotes growth by improving bile acid enterohepatic circulation. This study provides a reference for the regulation of DO and feeding in modern industrial intensive mariculture. Full article

(This article belongs to the Section Physiology and Biochemistry)

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14 pages, 1962 KiB

Open AccessTechnical Note

Application of Flow Cytometry to Determine Cell DNA Content in the Genetic Breeding of Fish

by Xinyan Zhu, Yang Chen, Xiaodie Zhang, Jiaxu Qiang, Lingtao Nie, Xinyue Luo, Binchao Liang, Kuo Chen, Fuzhong Yang, Rurong Zhao and Chun Zhang

Fishes 2025, 10(5), 227; https://doi.org/10.3390/fishes10050227 - 15 May 2025

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Abstract

In the field of fish genetic breeding, accurately determining the DNA content and ploidy of fish is of great significance. This article introduces the use of flow cytometry (FCM) to measure the DNA content and conduct ploidy analysis by sampling different tissues of [...] Read more.

In the field of fish genetic breeding, accurately determining the DNA content and ploidy of fish is of great significance. This article introduces the use of flow cytometry (FCM) to measure the DNA content and conduct ploidy analysis by sampling different tissues of freshwater fish species. It describes the FCM detection methods and their effectiveness for different individual tissues. These tissues include embryos and fry, as well as the blood, caudal fins, and sperm of adult live fish, and also specific tissues such as testes, ovaries, gills, spleens, and livers under anatomical conditions. Moreover, the application of ploidy detection to different tissues or individuals in different stages in the practice of fish genetic breeding is analyzed. This research covers samples from different growth stages and a variety of tissue types. The results show that this method exhibits high stability and reliability in the detection of different tissue samples, providing solid data support for subsequent research. It holds significant application value in fish genetic breeding. Full article

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14 pages, 2851 KiB

Open AccessArticle

Effect of Yeast Selenium on Growth Performance, Muscle Selenium Deposition, and Antioxidant Capacity of Juvenile Cherax quadricarinatus

by Ying Han, Chenchen Wang, Jimin Deng, Lizhen Zhong, Xiao Huang, Yuandong Sun and Xiaojuan Cui

Fishes 2025, 10(5), 226; https://doi.org/10.3390/fishes10050226 - 15 May 2025

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Abstract

This study aimed to investigate the effects of organic selenium-enriched yeast on the growth performance, muscle selenium deposition, and antioxidant capacity of juvenile Cherax quadricarinatus. Five experimental diets supplemented with 0.00 (control), 1.00, 2.00, 3.00, and 4.00 mg/kg of selenium-enriched yeast were [...] Read more.

This study aimed to investigate the effects of organic selenium-enriched yeast on the growth performance, muscle selenium deposition, and antioxidant capacity of juvenile Cherax quadricarinatus. Five experimental diets supplemented with 0.00 (control), 1.00, 2.00, 3.00, and 4.00 mg/kg of selenium-enriched yeast were fed to crayfish with an average initial body weight of (6.35 ± 1.66) g for 56 days. On days 0, 14, 28, 42, and 56 of the trial, 10 crayfish from each group were randomly sampled for body weight measurement. On day 28, the body weight of the crayfish fed diets containing 1.00, 2.00, 3.00, and 4.00 mg/kg selenium-enriched yeast was significantly higher (p < 0.05) than that of the control group. On day 56, the weight gain rate (WGR) and specific growth rate (SGR) of crayfish fed 1.00, 2.00, and 3.00 mg/kg selenium-enriched yeast were significantly elevated (p < 0.05) compared to those of the control group. Dietary selenium supplementation significantly enhanced muscle selenium deposition (p < 0.05), with deposition levels increasing proportionally to the supplementation levels within the same period. Selenium deposition initially increased, peaked at day 28 (significantly higher than the control), and then declined and stabilized. On day 42, the activities of pancreatic lipase (LPS), total superoxide dismutase (T-SOD), and acid phosphatase (ACP) in the hepatopancreas were significantly higher in the 3.00 and 4.00 mg/kg groups (p < 0.05). In comparison, trypsin activity was significantly increased in the 2.00 mg/kg and 3.00 mg/kg yeast selenium groups (p < 0.05). Alkaline phosphatase (AKP) activity was highly significantly elevated in the 2.00 mg/kg group (p < 0.01). On day 56, glutathione peroxidase (GSH-PX) activity in the hepatopancreas was considerably enhanced in all the selenium-supplemented groups (1.00–4.00) mg/kg (p < 0.05). In conclusion, the appropriate supplementation of selenium-enriched yeast promotes growth performance, enhances muscle selenium deposition, improves hepatopancreatic digestive enzyme activity, and strengthens antioxidant and immune capacities in Cherax quadricarinatus. Full article

(This article belongs to the Section Nutrition and Feeding)

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16 pages, 1907 KiB

Open AccessArticle

Taurine Enhances Antioxidant Enzyme Activity and Immune Response in Seriola rivoliana Juveniles After Lipopolysaccharide Injection

by Andressa Teles, Laura Guzmán-Villanueva, Marco A. Hernández-de Dios, Daniela A. Corona-Rojas, Minerva Maldonado-García and Dariel Tovar-Ramírez

Fishes 2025, 10(5), 225; https://doi.org/10.3390/fishes10050225 - 14 May 2025

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Abstract

Additives in fish feeds are used worldwide to provide better productivity and improve fish’s health in facing disease outbreaks. This study aimed to identify the protective effect of taurine on the immune-related parameters and antioxidant enzyme activities of Seriola rivoliana juveniles after being [...] Read more.

Additives in fish feeds are used worldwide to provide better productivity and improve fish’s health in facing disease outbreaks. This study aimed to identify the protective effect of taurine on the immune-related parameters and antioxidant enzyme activities of Seriola rivoliana juveniles after being challenged with LPS (lipopolysaccharide). Previously, the fish were submitted to a feeding trial for 60 days with feed enriched with different doses of external taurine (0, 1%, and 2%). Juveniles fed on different doses of taurine were injected with LPS (0%, LPS+T0%; 1%, LPS+T1%; 2%, LPS+T2%), and a control group was injected with saline solution (LPS-). The immune-related mRNA expression was evaluated, as were lysozyme enzyme activity and antioxidant enzyme activities (superoxide dismutase—SOD; catalase). Regarding immune mRNA expression, all the treatments had a peak of expression at 24 h post-LPS-injection, with a sharp decrease at 72 h post-injection, reaching similar mRNA expression as at 0 h post-injection. The results showed that the LPS+T2% treatment improved the expression of il1-β, tnf-α, and tlr-3 at 24 h post-LPS injection. Antioxidant and lysozyme activities were higher in both treatments with taurine when compared to the LPS+T0% and LPS- groups after 72 h post-LPS injection. These results suggest using 2% of exogenous external taurine can improve immunocompetency and counteract the oxidative stress caused by exposure to LPS in S. rivoliana juveniles. Full article

(This article belongs to the Special Issue Impacts of Dietary Supplements on Fish Growth and Health)

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16 pages, 924 KiB

Open AccessReview

Fish Welfare in the Ornamental Trade: Stress Factors, Legislation, and Emerging Initiatives

by Caroline Marques Maia, Ana Carolina dos Santos Gauy and Eliane Gonçalves-de-Freitas

Fishes 2025, 10(5), 224; https://doi.org/10.3390/fishes10050224 - 13 May 2025

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Abstract

The ornamental fish trade involves multiple phases, from acquisition—whether through wild capture or aquaculture—to the final destination, often including long transport routes. Throughout this trade, fish encounter several stressors like handling, improper maintenance methods, high or inadequate stocking densities, poor water quality, and [...] Read more.

The ornamental fish trade involves multiple phases, from acquisition—whether through wild capture or aquaculture—to the final destination, often including long transport routes. Throughout this trade, fish encounter several stressors like handling, improper maintenance methods, high or inadequate stocking densities, poor water quality, and mechanical disturbances during transport. The varying levels of care provided by aquarists also influence the long-term welfare of these animals, with many fish being treated more as ornaments rather than sentient beings. Worsening these issues, there is a lack of scientifically grounded guidance for hobbyists and caregivers, important gaps in legislation concerning fish welfare, and limited oversight in the ornamental trade. Nevertheless, some international organizations and grassroots projects have been working to promote responsible practices and disseminate educational resources. However, the need for efficient welfare standards, legislation, and comprehensive information for all stakeholders involved in this sector remains critical. Here, we synthesize the problems in the ornamental fish trade and suggest some solutions to reduce the impacts of management practices on the welfare of these fish. Full article

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

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37 pages, 1634 KiB

Open AccessReview

Assessing the Effects of Pesticides on Aquacultured Fish and Ecosystems: A Comprehensive Environmental Health Review

by Emily Burch, Mohamed Ali Hussein, Manar Zaki, Lereen T. Kamal, Ghada Zaki, Tamer Shoeib, Mahmoud Dawood, Hani Sewilam and Anwar Abdelnaser

Fishes 2025, 10(5), 223; https://doi.org/10.3390/fishes10050223 - 13 May 2025

Viewed by 532

Abstract

Aquaculture has been rapidly growing during the past decade to accommodate the increasing need for seafood as a vital source of nutrients for human beings. The nutritional benefits of incorporating fish into one’s diet are paramount in promoting overall health, bolstering immunity and [...] Read more.

Aquaculture has been rapidly growing during the past decade to accommodate the increasing need for seafood as a vital source of nutrients for human beings. The nutritional benefits of incorporating fish into one’s diet are paramount in promoting overall health, bolstering immunity and warding off diseases. Nonetheless, farm-raised aquatic species are frequently subjected to elevated contamination levels due to pesticides, antibiotics, and heavy metals in the marine environment. Pesticides affect fish differently based on species, class, dosage, and exposure duration. They can induce histological damage or neurobehavioral changes by inhibiting acetylcholinesterase production. This can promote liver dysfunction, metabolism deregulation, oxidative stress, and hematological imbalances, impair immune responses, and adversely affect fish reproduction. Furthermore, pesticides negatively affect the nutritional composition of fish by reducing the total protein levels in muscle, liver, gills, and kidney tissues. They disrupt lipid metabolism, resulting in lipid accumulation in the liver and a decrease in polyunsaturated fatty acids. Additionally, pesticides interfere with metabolism by altering carbohydrate levels in the gills, muscles, and kidneys while decreasing glycogen storage in the liver. Pesticide exposure has been linked to severe health impacts in humans, such as non-communicable diseases, reproductive issues, cognitive dysfunction, and cancer. The current review comprehensively emphasizes the harmful effects of pesticides on fish and human health, urging the establishment of environmental monitoring programs and biomonitoring studies. It accentuates the need for risk assessment models to evaluate pesticide impacts on marine ecosystems and advocates for stricter safety standards and lower pesticide residue limits in aquaculture products. Full article

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

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15 pages, 2390 KiB

Open AccessArticle

Effects of Stocking Density on Phytoplankton Community and Water Quality in Polyculture Ponds of Tegillarca granosa and Litopenaeus vannamei

by Jing He, Lin He, Zhihua Lin and Yongjian Xu

Fishes 2025, 10(5), 222; https://doi.org/10.3390/fishes10050222 - 12 May 2025

Viewed by 231

Abstract

This study investigated the effects of culture density on the phytoplankton communities in an integrated culture model of the blood clam Tegillarca granosa and Pacific white shrimp Litopenaeus vannamei. Two treatments were set up: L (L. vannamei 18 ind/m², [...] Read more.

This study investigated the effects of culture density on the phytoplankton communities in an integrated culture model of the blood clam Tegillarca granosa and Pacific white shrimp Litopenaeus vannamei. Two treatments were set up: L (L. vannamei 18 ind/m², T. granosa 33 ind/m²) and H (L. vannamei 36 ind/m², T. granosa 66 ind/m²). The management methods were the same during the experimental period, and the feed intake was determined according to L. vannamei. The results showed that there were more than 38 species of phytoplankton in the ponds, belonging to six phyla and 28 genera; the diversity index of the phytoplankton was higher in the early stage of the experiment and lower in the later stage; the average biomass of phytoplankton was 21.74 × 10⁴ ind/L; and the culture density had no significant effect on water quality. This study showed that a reasonable increase in culture density would not cause significant adverse effects on the environment. It is possible to increase the stocking density of shrimp with the mollusk without causing inadequate conditions for the phytoplankton community and water quality. Full article

(This article belongs to the Section Sustainable Aquaculture)

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17 pages, 3745 KiB

Open AccessArticle

Core–Shell Magnetic Gold Nanoparticles with Chitosan Coating as a SERS Substrate: A Rapid Detection Strategy for Malachite Green Contamination in Aquatic Foods

by Yihui Yang, Tao Huang, Sijia Hu, Hang Ye, Jiali Xing and Shengnan Zhan

Fishes 2025, 10(5), 221; https://doi.org/10.3390/fishes10050221 - 11 May 2025

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Abstract

In this study, we developed a novel SERS-active magnetic substrate (MBs@CS@AuNPs) for detecting malachite green (MG) in aquatic products, including shrimp, cod, and aquaculture water. The substrate combines chitosan-functionalized magnetic nanobeads with dense gold nanoparticles. It efficiently enriches MG through electrostatic and π–π [...] Read more.

In this study, we developed a novel SERS-active magnetic substrate (MBs@CS@AuNPs) for detecting malachite green (MG) in aquatic products, including shrimp, cod, and aquaculture water. The substrate combines chitosan-functionalized magnetic nanobeads with dense gold nanoparticles. It efficiently enriches MG through electrostatic and π–π interactions, generates high-density plasmonic hotspots for stable signals, and utilizes a superparamagnetic core to concentrate MG molecules. This design achieved an ultralow detection limit of 10⁻⁹ M for MG in aquaculture samples, with a linear range spanning from 10⁻³ to 10⁻¹⁰ M (R² = 0.999). The substrate demonstrated superior performance in untreated, complex food matrices (e.g., shrimp, cod), outperforming conventional magnetic mass spectrometry systems that are prone to matrix interference. This work introduces an innovative approach for detecting harmful residues in food during environmental safety monitoring. Full article

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7 pages, 593 KiB

Open AccessPerspective

Championing Line Breeding and Hybridization in Aquaculture to Safeguard Intellectual Property

by Gen Hua Yue

Fishes 2025, 10(5), 220; https://doi.org/10.3390/fishes10050220 - 9 May 2025

Viewed by 242

Abstract

Line breeding and line hybridization are pivotal genetic strategies in aquaculture, enabling breeders to enhance traits such as growth rate, disease resistance, and environmental tolerance in species like tilapia and Asian seabass. Though resource-intensive, these techniques yield long-term benefits, including improved productivity and [...] Read more.

Line breeding and line hybridization are pivotal genetic strategies in aquaculture, enabling breeders to enhance traits such as growth rate, disease resistance, and environmental tolerance in species like tilapia and Asian seabass. Though resource-intensive, these techniques yield long-term benefits, including improved productivity and sustainability. Traditional intellectual property (IP) protections, such as patents, are challenging to enforce in aquaculture because the biological replication and unauthorized breeding of aquatic species make it difficult to track and control proprietary genetic materials. Line hybridization offers a biological safeguard by producing hybrids that are challenging to replicate without access to proprietary parent lines. This inherent IP protection empowers breeders to safeguard their innovations, fostering sustainable growth and profitability in the aquaculture industry. Full article

(This article belongs to the Section Genetics and Biotechnology)

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14 pages, 6090 KiB

Open AccessArticle

Observations on the Biology and Fishery of the Marbled Spinefoot (Siganus rivulatus Forsskål & Niebuhr, 1775) in the Eastern Red Sea

by Zahra Okba, Eyüp Mümtaz Tıraşın and Mark Dimech

Fishes 2025, 10(5), 219; https://doi.org/10.3390/fishes10050219 - 8 May 2025

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Abstract

This study aims to enhance our understanding of the marbled spinefoot (Siganus rivulatus) population along the Red Sea coast of Saudi Arabia. It investigates whether the stock is subject to overfishing and tests the hypothesis that current fishing mortality exceeds sustainable [...] Read more.

This study aims to enhance our understanding of the marbled spinefoot (Siganus rivulatus) population along the Red Sea coast of Saudi Arabia. It investigates whether the stock is subject to overfishing and tests the hypothesis that current fishing mortality exceeds sustainable thresholds. A total of 6192 specimens were sampled during a comprehensive survey conducted from 2022 to 2024, utilizing a range of fishing methods, including handline, trap, gillnet, and demersal trawl fisheries. The sampled fish ranged in total length (TL) from 100 to 335 mm and in total weight (W) from 17 to 470 g. The length–weight relationship was W = 0.0175 × TL^2.92. Growth parameters derived from the von Bertalanffy model were TL_∞ = 43.5 cm, K = 1.12 year⁻¹, and t₀ = −0.18 year. The median size at first maturity was estimated at 14.83 cm TL for both sexes. Virtual Population Analysis revealed fishing mortality rates ranging from 0.01 year⁻¹ to 0.89 year⁻¹ across age classes 1 to 5 years, with exploitation levels of 0.6, 0.55, and 0.5 at ages 3, 4, and 5, respectively, indicating slight overfishing. The annual average catch of marbled spinefoot along the Saudi Arabian Red Sea coast was approximately 211 tonnes, contributing an estimated 1.8 million USD to the national economy. Maintaining the current fishing effort at sustainable levels is essential to ensure the long-term viability of this stock. Full article

(This article belongs to the Section Biology and Ecology)

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16 pages, 4306 KiB

Open AccessArticle

Integration of Biofloc and Ozone Nanobubbles for Enhanced Pathogen Control in Prenursery of Pacific White Shrimp (Penaeus vannamei)

by Qinlang Liang, Yazhi Luan, Zhengwen Wang, Jiangbo Niu, Yasong Li, Hua Tang, Zengting Li and Gang Liu

Fishes 2025, 10(5), 218; https://doi.org/10.3390/fishes10050218 - 8 May 2025

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Abstract

This study investigates the synergistic effects of integrating ozone nanobubbles (generated via a pure oxygen-fed reactor with nanobubble-diffusing air stones) and biofloc technology (BFT) on water quality optimization, pathogenic load reduction, and growth performance enhancement in Pacific white shrimp (Penaeus vannamei) [...] Read more.

This study investigates the synergistic effects of integrating ozone nanobubbles (generated via a pure oxygen-fed reactor with nanobubble-diffusing air stones) and biofloc technology (BFT) on water quality optimization, pathogenic load reduction, and growth performance enhancement in Pacific white shrimp (Penaeus vannamei) prenursery aquaculture systems. Four treatments were tested: a clear water control (CW), ozonated clear water (CW + O), biofloc (FLOC), and biofloc with ozone (FLOC + O). The FLOC + O group significantly improved water quality, reducing total ammonia nitrogen (TAN) by 61%, nitrite nitrogen (NO₂⁻-N) by 78% compared to CW, and total suspended solids (TSS) by 21% compared to FLOC (p = 0.0015). Ozone application (maintained above 0.3 mg/L, 15 min/day) demonstrated robust pathogen suppression, achieving a sharp reduction in Muscle Necrosis Virus (MNV), a 99.5% inhibition of Vibrio spp. (from 228,885 to 107 CFU/mL), and the clearance of Epistylis spp., as determined via optical microscope. These enhancements directly translated to superior biological outcomes, with the FLOC + O group exhibiting an 82% survival rate (vs. 40% in CW) and 13% higher final body weight (11.65 mg vs. 10.32 mg in CW). The integration of ozone and BFT also accelerated larval development and improved the Zoea II to Mysis I metamorphosis success rate. By maintaining stable microbial communities and reducing organic waste, the combined system lowered the water exchange frequency by 40% and eliminated the need for prophylactic antibiotics. These results demonstrate that ozone–BFT integration effectively addresses key challenges in shrimp prenursery—enhancing disease resistance, optimizing water conditions, and improving growth efficiency. The technology offers a sustainable strategy for the intensive prenursery of Pacific white shrimp, balancing ecological resilience with production scalability. Full article

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

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17 pages, 4541 KiB

Open AccessArticle

Design and Experiment of a Hard-Shell Clam Harvester

by Haiyun Wu, Xiaomeng Wang, Bing Huang, Shide Li, Jincheng Hu, Shancan Fu, Lei Yang, Mengxiang Cui, Zhenwei Chen, Yanan Zeng, Yongcheng Jiang and Tao Zhang

Fishes 2025, 10(5), 217; https://doi.org/10.3390/fishes10050217 - 7 May 2025

Viewed by 154

Abstract

Hard-shell clams are highly valued for their nutritional and economic benefits, leading to an increase in their aquaculture scale. Harvesting these clams manually leads to low efficiency and high labor intensity; thus, a new type of hard-shell clam harvester has been designed to [...] Read more.

Hard-shell clams are highly valued for their nutritional and economic benefits, leading to an increase in their aquaculture scale. Harvesting these clams manually leads to low efficiency and high labor intensity; thus, a new type of hard-shell clam harvester has been designed to overcome this challenge. Based on biological characteristics and sediment properties of hard-shell clams, a 3D model of the harvester has been created utilizing SolidWorks software (version 2022), which has a working length of 980 mm, an excavation depth range from 0~12 mm, and an angle of entry of 22 degrees. To optimize the efficiency of the machine, a Discrete Element Method (DEM) simulation trial was conducted through a three-factor three-level experiment using EDEM software. Results indicated an optimal harvest efficiency of 91.17% with the machine achieving a running speed of 0.526 m/s, roller speed of 4.772 r/min, and excavation depth of 73.067 mm. Field experiments verified the feasibility of the harvester, demonstrating high accuracy when compared to simulation results. Full article

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

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11 pages, 1991 KiB

Open AccessArticle

The Combined Effects of Multiple Invasive Species on Persistence of Imperiled Pahrump Poolfish

by Brandon L. Paulson, Kevin D. Guadalupe, Shawn C. Goodchild and Craig A. Stockwell

Fishes 2025, 10(5), 216; https://doi.org/10.3390/fishes10050216 - 7 May 2025

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Abstract

Many ecosystems have been invaded by more than one non-native species, but research evaluating the combined effects of multiple invasive species has been limited. In the southwest USA, many aquatic systems have been invaded by multiple species such as non-native crayfish and non-native [...] Read more.

Many ecosystems have been invaded by more than one non-native species, but research evaluating the combined effects of multiple invasive species has been limited. In the southwest USA, many aquatic systems have been invaded by multiple species such as non-native crayfish and non-native fishes. We document the rapid decline of a population of the endangered Pahrump Poolfish, Empetrichthys latos, which occurred following the sequential introduction of Red Swamp Crayfish, Procambarus clarkii, and Western Mosquitofish, Gambusia affinis. We also report the results of mesocosm experiment where we tested individual and combined effects of invasive Red Swamp Crayfish and Western Mosquitofish on experimental populations of Pahrump Poolfish. Survival rates were near 100% for adult poolfish in allopatry but were significantly lower for the other two treatments; when poolfish were sympatric with crayfish (~53%), and when poolfish were sympatric with both crayfish and mosquitofish (~55%). In allopatry, poolfish produced over 90 juveniles per mesocosm, while approximately 65 juveniles per mesocosm when poolfish were sympatric with crayfish, but this difference was not significant. However, juvenile production plummeted to near zero when poolfish were sympatric with both crayfish and mosquitofish. This study demonstrates that Pahrump Poolfish must be actively managed to detect and control invasive species, otherwise extinction will likely occur. This study also provides an example of the compounding effects of multiple invasive species. Full article

(This article belongs to the Section Biology and Ecology)

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10 pages, 447 KiB

Open AccessArticle

Kinetic Analysis of the Thermal Inactivation Behavior of AMP Deaminase and IMPase in Each Muscle Type of Yellowtail Seriola quinqueradiata

by Ayumi Furuta, Renri Okura, Chinatsu Kobayashi and Shota Tanimoto

Fishes 2025, 10(5), 215; https://doi.org/10.3390/fishes10050215 - 7 May 2025

Viewed by 211

Abstract

In this study, a kinetic analysis was conducted to clarify the thermal inactivation behavior of AMP deaminase and IMPase, enzymes involved in the generation and degradation of inosine 5′-monophosphate (IMP) in the dorsal ordinary muscle (OM) and dark muscle (DM) of yellowtail Seriola [...] Read more.

In this study, a kinetic analysis was conducted to clarify the thermal inactivation behavior of AMP deaminase and IMPase, enzymes involved in the generation and degradation of inosine 5′-monophosphate (IMP) in the dorsal ordinary muscle (OM) and dark muscle (DM) of yellowtail Seriola quinqueradiata. Both enzymes were extracted from each part of the fish muscle, heated in the range of 50–60 °C, and then measured for residual enzyme activity. Based on these data, kinetic analysis was performed. When comparing fish muscle types, the thermal stability at 50 °C and 55 °C and the temperature dependence of both AMP deaminase and IMPase tended to be higher in the DM. When comparing the two enzymes, the thermal stability of IMPase was higher than that of AMP deaminase at 50 °C in both muscle types. These results suggest that to prepare heated yellowtail muscle with a high IMP content, it is important to consider the thermal inactivation behavior of enzymes and use slow heating to maintain AMP deaminase activity and produce sufficient IMP in OM. For DM, rapidly increasing the product temperature to ≥60 °C to inactivate IMPase is required to preserve the IMP content. Full article

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

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24 pages, 2560 KiB

Open AccessArticle

Comparison of Bioinformatic Pipelines for eDNA Metabarcoding Data Analysis of Fish Populations

by Romulo A. dos Santos and Petr Blabolil

Fishes 2025, 10(5), 214; https://doi.org/10.3390/fishes10050214 - 6 May 2025

Viewed by 345

Abstract

Environmental DNA (eDNA) metabarcoding has gained popularity as a biomonitoring tool, leading to the emergence of various bioinformatic pipelines. However, comparisons are essential to assessing the reliability and similarity of results. In this study, we compared five bioinformatic pipelines (Anacapa, Barque, metaBEAT, MiFish, [...] Read more.

Environmental DNA (eDNA) metabarcoding has gained popularity as a biomonitoring tool, leading to the emergence of various bioinformatic pipelines. However, comparisons are essential to assessing the reliability and similarity of results. In this study, we compared five bioinformatic pipelines (Anacapa, Barque, metaBEAT, MiFish, and SEQme) using samples collected from three reservoirs in the Czech Republic during the autumn and summer seasons. Negative and positive controls were used to monitor potential contamination during sample processing. eDNA was amplified, targeting the 12S fish rRNA gene, sequenced, and analyzed with the selected bioinformatic pipelines. Statistical analyses were applied to assess result similarity, including the number of detected taxa, read count, alpha and beta diversities, and the Mantel test. Our findings showed consistent taxa detection across pipelines, with increased sensitivity compared to traditional methods. Alpha and beta diversities and the Mantel test also exhibited significant similarities between pipelines. Divergences were observed based on the reservoir, season, and their interaction. In conclusion, the choice of bioinformatic pipeline did not significantly affect metabarcoding outcomes or their ecological interpretation. Full article

(This article belongs to the Special Issue Fish DNA Barcoding)

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