UTTAR PRADESH JOURNAL OF ZOOLOGY

The intensification of aquaculture necessitates sustainable and effective strategies to enhance fish growth, health, and disease resistance while minimizing environmental impact. In this regard, green-synthesized nanoparticles have emerged as promising functional feed additives due to their biocompatibility and immunomodulatory potential. The present study evaluated the effects of dietary green-synthesized copper oxide nanoparticles (CuO NPs) on growth performance, hematological indices, immune responses, antioxidant status, and disease resistance in Oreochromis mossambicus over a 60-day feeding trial. Fish were fed diets supplemented with CuO NPs at 0, 1, 2, 4, and 8 mg/kg. Among the tested levels, 4 mg/kg significantly enhanced growth performance, as evidenced by increased final body weight, weight gain, and specific growth rate (p < 0.05). Hematological parameters, including hemoglobin, red blood cells, and white blood cells, were markedly improved, indicating enhanced physiological status. Innate immune responses—serum lysozyme activity, respiratory burst activity, and myeloperoxidase activity—were significantly elevated at this optimal dose. Antioxidant defense was strengthened, with increased superoxide dismutase and catalase activities and reduced malondialdehyde levels, reflecting mitigation of oxidative stress. Importantly, serum aspartate aminotransferase and alanine aminotransferase levels remained within normal ranges, indicating no hepatic toxicity. Following challenge with Streptococcus agalactiae, fish fed 4 mg/kg CuO NPs exhibited significantly higher survival rates compared to other groups. Collectively, these findings demonstrate that dietary supplementation with green-synthesized CuO NPs at 4 mg/kg enhances growth, immunity, and oxidative resilience without adverse effects, highlighting its potential as a sustainable nano-enabled strategy for improving aquaculture productivity and health management.