Difenoconazole (DFZ) is a persistent triazole fungicide that leads to aquatic toxicity and ecosystem damage due to its environmental persistence and high toxicity. Curcumin (CUR), a natural polyphenol derived from turmeric, exhibits strong anti-inflammatory, antioxidant, and antitumor properties. This study assesses CUR's protective role against DFZ-induced kidney injury in carp and investigates its mechanisms. Carp were exposed to DFZ for 30days, with dietary supplementation of 400mg/kg CUR. H&E staining revealed that CUR significantly reduced DFZ-induced histopathological damage in the kidneys. Dihydroethidium staining and biochemical assays demonstrated that CUR effectively lowered Reactive Oxygen Species levels and lipid peroxidation. Through biochemical kits, qPCR, and Western blotting, it was found that CUR decreased T-AOC and iron content, while activating the Nrf2/HO-1 pathway, thereby alleviating ferroptosis. CUR also upregulated the expression of xCT and GPX4, increased GSH levels, and further suppressed ferroptosis. In terms of inflammation, CUR improved the response by reducing pro-inflammatory cytokines (iNOS, IL-1β, IL-6, TNF-α) and increasing anti-inflammatory factors (IL-10, TGF-β1). With regard to apoptosis, CUR inhibited pro-apoptotic proteins (Bax, Cleaved-caspase3, Cleaved-caspase9, Cytochrome c) and restored the anti-apoptotic protein Bcl-2. In conclusion, CUR alleviates DFZ-induced kidney injury in carp by inhibiting ferroptosis through the Nrf2/GPX4 axis, while reducing oxidative stress, inflammation, and apoptosis. This study highlights CUR as a promising natural agent for mitigating environmental toxicity caused by triazole fungicides.

Cinnamon has emerged as a promising herbal supplement, revealing its potential in alleviating the harmful impacts of aquatic pollutants on various fish species. This study was conducted to investigate the protective potential of cinnamon (Cinnamomum zeylanicum) powder (CzP) in reducing waterborne-induced lead (Pb) toxicity in Labeo rohita. The research trial included six groups: a control group, a Pb-exposed group without CzP supplementation, and four Pb-exposed groups with CzP supplementation at dietary inclusion levels of 5, 10, 15, and 20g/kg in triplicates. Fish were fed at 5% of body weight for 60days. Upon completion of the experimental phase, several parameters were examined including growth performance, proximate body composition, intestinal enzyme activity, Pb accumulation in tissues, and hematological indices. The results demonstrated that waterborne Pb exposure negatively impacted all evaluated parameters. However, incorporating CzP into the diet notably improved physiological traits. The group supplemented with 10g/kg CzP exhibited significant improvements in growth, proximate composition, digestive enzyme activity, reduction in Pb accumulation, and blood profile of fish. In conclusion, our research demonstrates that dietary inclusion of CzP (especially at the level of 10g/kg) can significantly counteract Pb toxicity and enhance growth performance and health status of L. rohita.

The accumulation of metal toxicants in aquatic systems has been shown to create a harmful environment for marine life. This study examined the toxic effects of zirconium oxychloride (ZR) using Nile tilapia (Oreochromis niloticus) as a model organism. The fish were exposed to 10ppm, 20ppm, 40ppm, 60ppm, 80ppm, 100ppm, and 200ppm concentrations of ZR for 45days. Mortality rates in the treated groups were recorded through survival analysis, revealing a dose-dependent increase in mortality among Nile tilapia exposed to ZR. Behavioural changes were observed across all treated groups compared to the control. Histopathological analysis of gills, liver, intestine, and eye showed altered tissue structure in fish exposed to ZR. Biochemical evaluation of oxidative markers in the liver and intestine was also conducted for the first time in Nile tilapia exposed to ZR. Oxidative damage was detected through lipid peroxidation (LPX) levels, and the response of Nile tilapia to oxidative stress induced by ZR was assessed by examining superoxide dismutase (SOD) activity, catalase (CAT), and reduced glutathione (GSH) levels. Elevated LPX levels, along with increased activity of SOD, CAT, and GSH, were detected in the liver and intestines of all treated groups in a dose-dependent manner. These findings may help evaluate ZR toxicity in freshwater fish, especially in mining areas, and underscore the need for further research into the mechanisms of ZR-induced oxidative stress.

Microplastics (MPs) are one of the fastest-growing sources of pollution and have become a substantial risk to both the environment and human health. Hence, the present investigation was conducted to assess the potential toxic effects of Polyvinyl chloride (PVC) MPs (Treatment I- 3µg/L and Treatment II- 30µg/L) on D. rerio for 20days. The PVC-MPs were characterised by SEM, XRD, DLS and FTIR analyses, and their presence was confirmed in the gastrointestinal tract of the fish. When compare to the control group, the studied locomotive, behavioural, blood (haematology) and tissue (gill, gut and brain) biomarkers (SOD, GST, GPx, LPO, AChE, histopathology) were altered significantly (P < 0.05) in the PVC-MPs treatment groups. Locomotive and behavioural responses declined. Among the blood biomarkers, RBC counts were increased significantly in the PVC-MPs treatments. Whereas, WBC counts were decreased. Tissue (gill, gut and brain) SOD and GPx activity was accelerated in the PVC-MPs treated fish. In contrast, the GST activity in the gill, gut, and brain tissues were declined. LPO levels in the gill of the PVC-MPs fish were increased. PVC-MPs inhibited AChE activity in the brain tissue of fish. No visible histological changes were noticed in the control group. Whereas, a series of histological anomalies were visualized in the gill, gut and brain tissues of the PVC-MPs. These biomarker-responses of fish reveals that PVC-MPs is potentially a toxic substance to non-target organisms. The studied locomotory, behavioural, haematological, antioxidants, AChE and histopathology are useful biomarkers to asses potential toxicity of plastic related materials on aquatic organisms.

Allicin, a bioactive sulfur compound from garlic known for its antimicrobial and immunomodulatory properties, was evaluated in this study for its effects on growth, antioxidant activity, gut microbiota, and antibiotic resistance genes (ARGs) in Trachidermus fasciatus. Fish were administered allicin at concentrations of 100mg/kg, 200mg/kg, and 300mg/kg. The 200mg/kg allicin group had significantly higher WGR, LGR, and SGR than the control group. Hepatic SOD and LZM activities were also higher in the 200mg/kg group. Metagenomics showed that allicin altered the gut microbiota composition, decreased the diversity, and altered the community structure. Allicin-treated fish had significantly reduced levels of potentially damaging bacteria, including Pseudomonas and Vibrio species. The ARGs showed that genes associated with multidrug resistance, including specific subtypes, were markedly reduced in the 200mg/kg allicin-treated fish. The control group had a markedly decreased number of genes resistant to β-lactam antibiotics. Allicin reduced the number of genes resistant to rpoB2 and mdtC, suggesting the potential for antibiotic resistance. Network analysis of co-occurrence patterns showed that genes resistant to multiple drugs, tetracyclines, and peptides were prevalent, with most possible potential host taxa belonging to Ascomycota and Firmicutes. These results indicate the importance of allicin for fish health as a sustainable alternative to antibiotic resistance and provide a viable alternative to antibiotic resistance for fish farming.

Heat Shock Proteins (HSPs) act as molecular chaperones, protecting cells by stabilizing and refolding damaged proteins under stress. While the induction of HSPs in fish under stress is well-documented, comprehensive genome-wide analyses of the entire HSP90 gene family in a comparative context remains limited. This study provides a systematic, comparative analysis of the HSP90 gene family in two economically important species with distinct thermal niches, Cyprinus carpio (common carp) and Oreochromis niloticus (Nile tilapia). Our investigation included phylogenetic relationships, motif patterns, physicochemical properties, positive selection, and expression profiles. Key findings include the identification of tandem duplications in both species and a higher number of transcription factor-binding sites (TFBSs) in tilapia compared to common carp. Positive selection analysis revealed significant evidence of adaptive evolution in the HSP90 proteins. qRT-PCR analysis revealed organ-specific responses and differing thermal tolerances, with O. niloticus exhibiting a more pronounced adaptive response to extreme heat (40 °C). These findings provide valuable insights into the evolutionary dynamics and functional divergence of the HSP90 gene family, offering a theoretical basis for understanding genetic adaptations to thermal stress. As global temperatures rise, such insights are essential for enhancing aquaculture sustainability by leveraging natural adaptive mechanisms.

This study evaluated the impact of dietary inclusion of red onion peel extract (ROPE) on body composition, growth, feed utilization, immune response, antioxidant status, and economic efficiency of Oreochromis niloticus reared under high stocking density. A total of 630 mono-sex Nile tilapia (6.09 ± 0.11g) were randomly distributed into four groups (n = 3 outdoor concrete tanks per treatment; 1 m3 water/tank). The experimental groups were: G1, low stocking density (30 fish/tank, basal diet); while G2, G3, and G4, high stocking density (60 fish/tank) supplemented with 0, 250, and 500mg/kg ROPE, respectively. Fish were fed to apparent satiation three times daily for 14weeks. Results showed that fish subjected to high stocking density (G2) exhibited reduced weight gain, final body weight and protein efficiency ratio, along with elevated feed conversion ratio compared to low-density group (G1). However, supplementation with ROPE significantly improved these growth and feed utilization indices (P < 0.01). Whole-body composition (moisture, protein, lipid, ash) did not differ significantly among treatments (P > 0.05). Additionally, G3 and G4 showed enhanced blood total protein and albumin levels, reduced alanine aminotransferase activity, and lower serum lipid peroxidation (P < 0.05). Antioxidant enzyme activities (catalase and reduced glutathione) and immune parameters (lysozyme activity and immunoglobulin M) were significantly elevated in ROPE-supplemented groups (P < 0.05). Economically, G4 yielded the highest final and relative profit margins among all high-density groups. In conclusion, dietary supplementation with 500mg/kg ROPE effectively mitigated the adverse impacts of high stocking density by enhancing growth metrics, physiological health, and economic returns in Nile tilapia.

Nutritional programming could potentially be a strategy for sustainable aquaculture to adapt fish to feeds formulated with low levels of marine ingredients. The present study examined the effects of early dietary stimulus duration and the impacts of a later challenge with a similar diet. At first feeding, Atlantic salmon (Salmo salar) fry of ~ 0.15g initial weight were fed a vegetable diet (77% plant-based ingredients) for either 1 (V1) or 2weeks (V2), while a control group (M) received a marine diet (86% marine-based ingredients) for the 2weeks (stimulus phase). All fish then received a marine diet for 16weeks (intermediate phase) before being refed a vegetable diet for 6weeks (challenge phase). Water temperature was 13°C during the trial, and the only difference between the three experimental groups (V1, V2 and M) was their dietary regime during the first 2weeks. Obviously, stimulus duration had no phenotypic impacts on growth or tissue fatty acid compositions of either total or polar lipids after challenge. However, the expressions of key genes of LC-PUFA biosynthesis were upregulated significantly in the V1 group, whereas the expressions of most transcription factors were downregulated in the V2 group. After the challenge, the circular muscle thickness of the intestine in the V1 group was increased by 15%, and goblet cell numbers were reduced by 15%. Overall, further investigations about the duration of the stimulus and assessment with longer challenges are required to elicit positive effects and to refine the use of nutritional programming in Atlantic salmon.

A 60-day feeding trial was conducted to evaluate the effects of iron-porphyrin (FePh) supplementation (0, 50, 100, 150, and 200mg/kg Fe3⁺) compared with 50mg/kg FeSO4 in juvenile Epinephelus cyanopodus (16.12 ± 0.15g). The results demonstrated that FePh at 100mg/kg maximized the growth performance (P < 0.05), while 50mg/kg FePh surpassed FeSO4 in enhancing intestinal barrier integrity and growth. FePh improved systemic iron metabolism by elevating elevated transferrin and hepcidin levels (P < 0.05), with 50mg/kg FePh significantly increasing hemoglobin and serum iron (P < 0.05). Antioxidant capacity was significantly enhanced (T-AOC and SOD in serum and gills), alongside the upregulation of immune markers (C3, C4, and IgM). FePh also improved intestinal morphology (GC, MP, VL) and intestinal microbiota (P < 0.05). Serum aminotransferase (ALT and AST) levels decreased with elevated activity of antioxidant enzymes. Transcriptomic analysis revealed that FePh suppressed ferroptosis-related genes acsl4 and fth1, while activating iron-regulation genes slc7a11, slc3a2, and hmox1. In conclusion, FePh effectively improved the growth of juvenile E. cyanopodus; enhanced antioxidant capacity, non-specific immunity, and iron metabolism; maintained the stability of the intestinal mucosal barrier to promote intestinal health; and regulated the expression of key genes in the ferroptosis pathway to protect liver health. The optimal FePh inclusion level was 50-100mg/kg, demonstrating superior efficacy over inorganic iron for sustainable grouper aquaculture.