This study examined the effects of dietary ellagic acid (EA) on growth performance, survival, immune responses, and oxidative status of common carp (Cyprinus carpio) exposed to high stocking density (HSD). A 2 × 3 factorial design was used, with two stocking densities (25 and 100 kg/m³) and three EA levels (0, 50, and 100 mg/kg diet). HSD significantly reduced growth performance, as indicated by lower weight gain and specific growth rate (SGR), increased feed conversion ratio (FCR), and decreased survival (p < 0.05). It also suppressed immune responses, including white blood cell count (WBC), nitroblue tetrazolium activity (NBT), phagocytic activity (PA), lysozyme activity (LYZ), and bactericidal activity (BA). Furthermore, HSD increased malondialdehyde High stocking density caused (MDA) levels and decreased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities in liver, head kidney, and spleen tissues (p < 0.05). Fish were challenged by intraperitoneal injection of Aeromonas salmonicida subsp. achromogenes. Dietary EA supplementation significantly improved survival under both stocking densities, with the highest survival observed in fish receiving 100 mg/kg EA. Kaplan–Meier survival analysis and log-rank tests confirmed significant differences among treatment groups (p < 0.05). Pairwise comparisons further demonstrated that EA, particularly at 100 mg/kg, enhanced survival under high-density conditions. EA supplementation also improved growth performance, antioxidant status, and immune responses in a dose-dependent manner. Polynomial contrast analysis revealed significant linear trends: increasing EA levels enhanced weight gain, antioxidant enzyme activities, and immune parameters, while reducing MDA levels (p < 0.05). Significant SD × EA interactions indicated that EA alleviated the adverse effects of crowding stress. In silico analyses showed higher binding affinity of EA toward SOD, CAT, and GSH-Px. Overall, dietary EA effectively mitigated density-induced oxidative stress and immunosuppression, supporting its potential as a functional feed additive in intensive aquaculture.

Oxytetracycline (OTC) is a broad-spectrum antibiotic widely used in aquaculture for the treatment of bacterial diseases caused by important fish pathogens, including Aeromonas, Pseudomonas, Vibrio, and Lactococcus spp. Although OTC remains an important therapeutic agent in fish farming, its use may also induce undesirable physiological effects, including hematological disturbances, immunosuppression, and oxidative stress. This study investigated the protective effects of dietary curcumin against OTC-induced physiological alterations in rainbow trout (Oncorhynchus mykiss). Fish were fed diets supplemented with 0, 10, 50, or 100 mg kg⁻¹ curcumin for eight weeks, followed by exposure to 0, 50, and 75 mg L⁻¹ OTC for 48 h. Hematological variables, innate immune responses, and oxidative stress biomarkers were comprehensively evaluated. OTC exposure significantly disrupted physiological homeostasis by reducing red blood cell (RBC) count, hemoglobin (Hb), hematocrit (Ht), mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH). Furthermore, white blood cell (WBC) count, nitroblue tetrazolium (NBT) activity, phagocytic activity (PA), phagocytic index (PI), total protein (TP), immunoglobulin M (IgM), bactericidal activity (BA), lysozyme activity (LYZ), and myeloperoxidase (MPO) activity were significantly decreased, indicating marked suppression of both cellular and humoral innate immune responses. Oxidative stress was characterized by increased malondialdehyde (MDA) concentrations together with reduced superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), and reduced glutathione (GSH) levels, whereas glutathione S-transferase (GST) activity increased following OTC exposure. Dietary curcumin supplementation generally improved hematological and immune indices and was associated with reduced lipid peroxidation and improved antioxidant status. However, the magnitude and statistical pattern of these responses varied among parameters and tissues, and significant CUR × OTC interactions were not observed for all endpoints. Overall, dietary curcumin supplementation progressively attenuated these alterations, although the response pattern varied among parameters. Increasing dietary curcumin supplementation generally led to greater physiological improvement, although the response varied among endpoints. Notably, at 75 mg/L OTC, supplementation with 100 mg/kg curcumin, compared with 0 mg/kg curcumin, increased RBC count by approximately 14.5%, Ht by 47.8%, WBC count by 32.2%, and NBT activity by 38.9%. In the liver, the same treatment reduced MDA by approximately 14.6% and increased SOD activity and GSH levels by 48.7% and 47.2%, respectively (p < 0.001 for all). The highest dietary curcumin level generally produced the greatest physiological improvement. In conclusion, dietary curcumin effectively mitigated OTC-induced hematological, immunological, and oxidative disturbances in rainbow trout, highlighting its considerable potential as a functional feed additive to improve fish health, enhance physiological resilience under antibiotic-associated stress, and support more sustainable aquaculture practices.

Epilepsy is associated with recurrent seizures and behavioral and cognitive disturbances, highlighting the importance of assessing behavioral outcomes alongside seizure severity. Caffeic acid phenethyl ester (CAPE) has shown neuroprotective activity, whereas evidence for the neurobehavioral effects of 10-hydroxy-2-decenoic acid (10-HDA) remains limited. This study investigated their individual and combined dietary effects on seizure-like behavior and behavioral test performance in adult zebrafish (Danio rerio) challenged with pentylenetetrazol (PTZ). Fish received experimental diets for 8 weeks before exposure to 15 mM PTZ. A dietary valproic acid group was included as a comparator. Outcomes included behavioral seizure scores, the area under the seizure score–time curve (AUC), and performance in the novel tank diving and Y-maze tests. Compared with PTZ alone, CAPE, 10-HDA, and their combination reduced seizure scores and AUC values and increased upper-zone and novel-arm exploration (p < 0.05). The combined group spent more time in the novel arm than either single-compound group (p < 0.05), although its advantages varied across endpoints and pharmacological synergy was not established. Overall, dietary CAPE and 10-HDA were associated with lower behavioral seizure scores and improved test performance following acute PTZ challenge. Further studies are needed to distinguish these responses from independent effects on baseline behavior and the influence of seizure severity and motor function.

Potassium permanganate treatment can adversely affect fish physiology despite its usefulness in aquaculture. This study evaluated the protective effects of dietary curcumin against potassium permanganate-induced disturbances in common carp (Cyprinus carpio). Fish were fed a basal diet or diets supplemented with 1%, 2%, or 4% curcumin for eight weeks, with or without subsequent exposure to potassium permanganate at 2 mg/L for 30 min daily for seven days. Hematological and immune parameters and oxidative status in the liver, kidney, spleen, and gill were assessed. Potassium permanganate exposure altered blood and immune parameters, increased lipid peroxidation, and weakened antioxidant defenses. Curcumin supplementation alleviated these effects, with protection evident at 1%, the lowest dietary inclusion level tested, and further improvements in selected parameters at 4%. Inclusion levels below 1% were not evaluated, so the minimum effective level remains unknown. Molecular docking predicted interactions between curcumin and the antioxidant enzymes SOD, CAT, GPx, and GST at structurally plausible binding sites. These computational findings were interpreted alongside the biological results as supportive, hypothesis-generating evidence rather than confirmation of functional effects on these enzymes in vivo. Overall, dietary curcumin showed potential to reduce the physiological disturbances associated with repeated potassium permanganate exposure. Further dose–response studies should evaluate inclusion levels below 1% to identify effective and economically viable supplementation rates and determine whether curcumin affects the antiparasitic or antibacterial efficacy of potassium permanganate.

Copper sulfate (CuSO₄) is one of the most widely used chemotherapeutic agents in aquaculture and aquatic veterinary medicine because of its broad-spectrum antiparasitic, antifungal, and antimicrobial activities. However, repeated exposure may induce oxidative stress and impair hematological and immune functions, thereby compromising fish health. This study evaluated the effects of pre-exposure and post-exposure dietary ellagic acid (EA) supplementation on CuSO₄-induced hematological, immunological, and oxidative stress alterations in common carp (Cyprinus carpio). A total of 150 fish were randomly allocated to five experimental groups: Control, EA, CuSO₄, pre-exposure EA + CuSO₄, and post-exposure CuSO₄ + EA. Fish were fed a diet supplemented with 100 mg EA kg⁻¹ feed for 14 days either before or after repeated CuSO₄ exposure (1 mg L⁻¹, 30 min day⁻¹ for seven consecutive days). Hematological variables, innate immune responses, and oxidative stress biomarkers were subsequently evaluated. CuSO₄ exposure significantly decreased red blood cell (RBC) count, hemoglobin (Hb), hematocrit (Ht), phagocytic activity (PA), phagocytic index (PI), total plasma protein (TP), immunoglobulin M (IgM), bactericidal activity (BA), lysozyme (LYZ), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), and reduced glutathione (GSH), while significantly increasing mean corpuscular hemoglobin concentration (MCHC), white blood cell (WBC) count, respiratory burst activity (NBT), myeloperoxidase (MPO), and malondialdehyde (MDA) (p < 0.05). Dietary EA supplementation markedly alleviated these alterations by restoring hematological homeostasis, improving innate immune responses, reducing lipid peroxidation, and reinforcing antioxidant defense systems in the liver, kidney, spleen, and gill. Both pre-exposure and post-exposure EA supplementation were associated with improvements in the evaluated biomarkers under the experimental conditions of the present study. However, because the two supplementation strategies were not evaluated against a time-matched CuSO₄ recovery control group, the present study does not permit a direct comparison of their relative efficacy. These findings demonstrate that dietary EA was associated with improvements in hematological, immunological, and oxidative stress biomarkers following experimental CuSO₄ exposure, potentially through antioxidant and immunomodulatory mechanisms. Therefore, dietary EA may serve as a promising functional feed additive to support antioxidant and immune status during experimental CuSO₄ exposure in common carp. Further studies including pathogen challenge models are required before its use as an adjunct to CuSO₄ treatments can be recommended.