The scarcity of functional females in wild Centropomus undecimalis populations limits broodstock development for aquaculture. This study evaluated feminization of this protandrous hermaphroditic teleost under different salinity conditions using 17β‐estradiol (E2), administered orally to juveniles and via intramuscular implants to adults. Two factorial experiments assessed E2 effects on histological, hormonal, molecular, and zootechnical parameters. Complete feminization was achieved in both juveniles and adults, as confirmed by histological analysis and upregulation of female sex and reproduction‐related genes ( foxl2a , cyp19a1a , zar1l , ddx5 , and H2A ), with the most pronounced responses under marine conditions. Hormonal assays indicated increased plasma vitellogenin (Vtg) and reduced 11‐ketotestosterone (11‐KT) in treated groups, reflecting suppression of male endocrine pathways. Zootechnical performance in adults was not significantly affected. However, juveniles reared in freshwater demonstrated superior feed conversion and protein efficiency compared to those in marine conditions, independent of hormone treatment, indicating that salinity influences growth efficiency. These results confirm that E2‐induced feminization is highly effective across salinities and life stages, with salinity modulating molecular and productive outcomes, offering practical recommendations for broodstock development and sustainable management of wild snook populations.

Handling stress is a significant challenge in intensive aquaculture, often compromising fish welfare, immunity, and overall productivity. This study investigates the skin transcriptomic responses, blood plasma enzyme activities, and histological changes in the liver, spleen, and head kidney of hybrid grouper ( Epinephelus fuscoguttatus × E. lanceolatus ) subjected to repeated handling stress over 10 consecutive days. RNA‐sequencing of the skin identified 2521 differentially expressed genes (DEGs), showing significant enrichment in oxidative phosphorylation and cardiac muscle contraction pathways. Stress conditions upregulated genes such as NADH ubiquinone oxidoreductase , ATP synthase , cytochrome b-c1 complex , cytochrome c oxidase , succinate dehydrogenase complex subunit B , and troponin T2d cardiac , indicating enhanced mitochondrial activity and energy turnover. These molecular signatures correlated with physiological recovery in stress‐resilient (handling‐resilient [HR]) fish, as evidenced by elevated alanine transaminase levels and preserved hepatic morphology. In contrast, stress‐sensitive (handling‐sensitive [HS]) fish exhibited a pronounced reduction in hepatic cytoplasmic area (48.75 ± 0.47 μm 2 ) compared to the control (62.47 ± 0.20 μm 2 ) and HR (67.82 ± 0.24 μm 2 ) groups. Furthermore, HS fish showed severe splenic necrosis (3.15 ± 0.68 μm 2 ) compared to the control (0.27 ± 0.29 μm 2 ), reflecting impaired metabolic and antioxidant capacity. This integrated analysis elucidates the molecular and physiological impacts of handling stress and identifies key pathways linked to stress resilience. Implementing refined handling techniques is essential to mitigate stress‐related health impacts and enhance welfare in hybrid grouper aquaculture.

This study investigated the effects of cadmium (Cd), microplastics (MPs), and pectin (Pec) supplementation on biochemical, oxidative, and immunological parameters in crayfish ( Astacus leptodactylus ). Four hundred fifty crayfish were acclimatized under controlled laboratory conditions and distributed into 15 experimental groups using a definitive screening design (DSD) approach. The groups were exposed to varying combinations of Cd (0, 20, and 40 µg/L), MP (0, 50, and 100 mg/L), and Pec‐supplemented diets (0%, 0.25%, and 0.5% per kg feed) for 45 days. The findings showed that Pec supplementation increased superoxide dismutase (SOD) and glutathione (GSH) peroxidase (GPx) activities but did not affect catalase (CAT) activity. Cd and MPs reduced SOD, CAT, and GPx activities, with Pec partially restoring CAT activity. Exposure to Cd and MPs elevated alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, triglycerides, cholesterol, creatinine, and glucose levels, while gamma‐glutamyl transpeptidase, lysozyme, total protein, and albumin decreased. Pec normalized triglyceride and alkaline phosphatase (ALP) activity but showed limited protective effects on GPx, cholesterol, creatinine, and glucose regulation. The results indicated that because crayfish were directly exposed to MPs and Cd, oral administration of the Pec supplement failed to restore some biochemical parameters to normal levels. These findings indicate Pec’s selective efficacy in mitigating Cd‐ and MP‐induced stress in crayfish.

Amoebic gill disease (AGD), caused by Neoparamoeba perurans , is a challenge for Atlantic salmon aquaculture. Research has, therefore, focused on detecting/monitoring N. perurans loads within/around fish pens. Recently, molecular methods to detect N. perurans have been used to reduce labour‐intensive sampling, inconsistency, and stress on stock while complementing gill scoring and histology methods for AGD assessment. Molecular detection depends on reliable and cost‐effective sample collection. Recent studies have demonstrated the potential for utilising naturally occurring filter‐feeding animals as a mechanism for collecting DNA from the environment (i.e., ‘natural samplers’) for use in downstream molecular assays. This opens the possibility of sampling with minimal training or expertise, offering the potential to easily integrate this sampling within normal farm operations. We evaluated, through aquarium‐based experiments, the utility of the Pacific oyster ( Magallana gigas ) to collect N. perurans DNA from the water column. In aquaria inoculated with N. perurans , total water column amoeba load decreased significantly over time in the presence of oysters. Despite this decrease, no correlation between the level of amoeba accumulation within oysters and the decrease in the water column was observed. N. perurans was detected in every oyster organ type tested (mantle, gill, palp, and digestive gland), though with high variation. The detection of N. perurans DNA within the digestive gland indicates that oysters ingested amoeba. Oysters were found to be viable environmental DNA (eDNA) samplers for N. perurans , providing a useful collection method.

Understanding species‐specific physiological flexibility in Indian major carps (IMCs) is crucial for enhancing thermal resilience, safeguarding health, and sustaining year‐round productivity in climate‐sensitive freshwater systems. This study examined the seasonal physiological adaptability of three Indian main carps ( Labeo rohita , Gibelion catla , and Cirrhinus cirrhosus ) by measuring growth performance, proximate composition, and hematological profiles in both overwintering and summer aquaculture environments. It was hypothesized that seasonal heat changes would cause species‐specific metabolic and immunological responses, indicating varying tolerance to environmental stress. All IMC species exhibited enhanced growth during the summer season, for example, G. catla exhibited the highest specific growth rate (SGR) of 1.26 ± 0.13%/day and average daily growth (ADG) of 2.56 ± 0.32 g than the other species. Moisture dominated the proximate composition, while protein and lipid contents declined in winter. Hematological analysis manifested seasonal and species‐specific physiological responses to environmental stressors. Increased concentrations of white blood cells (WBCs), monocytes, glucose, and mean corpuscular volume (MCV) in fish blood denoted that higher temperature in summer attributes to increased metabolic activities and improved immune responses. Conversely, reduction in hematocrit (HCT) levels during winter in G. catla (32.53 ± 0.54%) and C. cirrhosus (33.14 ± 1.35%) suggests a physiological adaptation to lower oxygen availability, potentially reflecting a seasonal modulation of erythropoiesis and oxygen‐carrying capacity under cold‐induced hypoxic stress. Furthermore, the elevation in serum creatinine levels in all experimented IMCs during winter suggested potential changes in renal activity due to fish physiological adjustments in winter. The findings highlight the importance of better aeration, water exchange, and ammonia control in summer and careful stocking with minimal handling in winter to reduce stress in overwintering ponds.

Barnacle aquaculture is a developing area of production that is currently limited by the reliance on capturing naturally produced larvae. The solution to this limitation would be the development of hatcheries for culturing barnacle larvae and juveniles (Juvs). The giant barnacle Austromegabalanus psittacus (Molina 1788) is an edible species and, thus, of economic importance in Chile. Extensive cultures and hatcheries on an experimental scale have been developed for this species. In this study, a dynamic model, based on data from previously published studies, was developed to evaluate the larval development of A. psittacus over a range of temperatures and salinities in order to identify the optimal culture conditions for obtaining Juvs. The larval development time, survival, physiological, and biochemical responses of A. psittacus larvae were evaluated. The conceptual model representing the dynamic hypothesis, and the simulations, were carried out using Vensim PLE and Stella Architect, respectively. The best production performance under hatchery conditions was obtained at 18°C/32 PSU. Under these conditions, the survival during the development of the nauplius (Nau) stages was 90%, and the development time was 7.5 days. The recently molted cyprids (Cyps) had an accumulated energy of 24.42 J/mg dry weight (dw). At the Cyp stage, the development time was 6 days and the survival was 54%, while the energy of the Juv was 12.02 J/mg dw. Increasing the initial energy of Nau I (NI) resulted in higher survival and energy in the Cyp and Juv stages. These simulations demonstrate the usefulness of these dynamic models in designing and evaluating hatchery protocols that optimize the performance of A. psittacus larvae and may allow scaling to mass cultivation.

The use of marine collagen for regenerative applications is rapidly expanding. Tilapia ( Oreochromis niloticus ) skin is an emerging byproduct of food industry and a valuable biomaterial known for its pro‐regenerative properties. Enhancing its intrinsic composition through nutritional strategies could further improve its clinical potential. This study investigates the impact of a hydrolyzed collagen‐enriched diet on the skin properties of aquaponically farmed Tilapia, with the aim of enhancing collagen content while preserving tissue homeostasis. The results showed a modulation of key amino acids and fatty acids, suggesting a favorable shift toward anti‐inflammatory and pro‐regenerative properties. A measurable increase in skin thickness and hydration was registered, as well as an ECM remodeling. No detrimental effects on mineral content or mechanical integrity were observed. These findings demonstrate that dietary supplementation with collagen can be an effective, non‐invasive, approach to improving the biomedical quality of fish‐derived skin products.

Feed processing technology choice between extrusion and pelleting remains a critical decision in aquaculture nutrition. We conducted a systematic review and meta‐analysis of 40 comparisons from 23 studies to evaluate the growth performance effects of extruded versus pelleted feeds. While conventional random‐effects models indicated an overall benefit of extruded feeds (Hedges’ g = 0.97, 95% CI: 0.49–1.45), extreme heterogeneity ( I 2 > 99%), and a nonsignificant multilevel model accounting for study dependencies ( g = 0.53, p = 0.075) revealed context‐dependent effects. Meta‐regression identified species identity as the primary moderator, explaining 62.1% of heterogeneity. Nutritional composition was also significant: dietary lipid content improved growth, while higher ash content in extruded diets reduced efficacy. These findings demonstrate that feed processing outcomes are not technology‐inherent but are mediated by species‐specific biology and nutritional interactions. Optimal feed selection should, therefore, prioritize integrated consideration of species requirements and nutritional formulation over processing method alone.

Global aquaculture expansion necessitates sustainable technologies like biofloc technology (BFT), and the type of carbon source exerts a crucial impact on the functionality of biofloc systems. This study aimed to evaluate the effects of single carbon sources (glucose [G] and maltodextrin [M]) and their 1:1 mixture (GM) on water quality, microbial communities, growth performance, and physiological status of redclaw crayfish ( Cherax quadricarinatus ) in BFT systems, with a clear‐water group (F) as the control. A 70‐day experiment was conducted in triplicate tanks per treatment, with key parameters (water quality indices, microbial diversity via 16S rRNA sequencing, growth metrics, and hepatopancreatic antioxidant enzyme activities) measured. Data were analyzed using one‐way ANOVA followed by Tukey’s Honestly Significant Difference (HSD) test ( p < 0.05). Key findings showed that the GM group exhibited significantly higher microbial alpha diversity (Shannon index and Simpson index; p < 0.05 vs. all groups) and stronger functional redundancy, enriched with synergistic taxa such as Dechloromonas and Chryseolinea . Compared to the F group, all BFT groups significantly improved production yield (GM: 135.72 g vs. F: 119.35 g; p < 0.05), survival rate (GM: 88.89% vs. F: 70.22%; p < 0.05), and feed conversion ratio (GM: 1.72 vs. F: 1.89; p < 0.05), with GM performing optimally among BFT groups. The GM group also maintained a balanced carbon‐to‐nitrogen ratio (C:N) and stable total suspended solids (TSS) dynamics, while crayfish in GM showed significantly enhanced superoxide dismutase (SOD) and total antioxidant capacity (T‐AOC) and reduced malondialdehyde (MDA) levels ( p < 0.05). All biofloc systems demonstrated economic viability (benefit‐cost ratios (BCRs) > 1.40). This research provides a practical microbial‐based strategy for improving redclaw crayfish culture and crustacean aquaculture sustainability via optimized carbon source management in BFT.

With the global aquaculture industry growing rapidly, fishmeal (FM) occupies an important position in aquatic animal nutrition as a traditional feed ingredient, but its production is facing rising costs and sustainability challenges, making the search for high‐quality heterologous proteins particularly essential. The effects of different protein substitutes for FM in the diets of Chinese soft‐shelled turtles ( Pelodiscus sinensis ) have been evaluated through a review and meta‐analysis, focusing on their impact on the growth performance, immune response, and health status of the turtles. This meta‐analysis evaluates the effects of heterologous protein substitutions for FM in the diet of Chinese soft‐shelled turtles ( Pelodiscus sinensis ). A total of 10 studies with 37 independent datasets were included, revealing that FM significantly outperforms all alternatives in promoting weight gain (β = 12.18, 95% CI [7.77, 16.58], p < 0.001). Despite the nutritional potential of heterologous proteins, a dose–response reversal phenomenon was observed at higher inclusion levels. These findings underscore the importance of optimizing protein substitution ratios for sustainable aquaculture practices.