Impact of zinc supplementation on growth, antioxidant status, and physiological health of Cyprinus carpio (Common Carp): Evaluating the optimal dietary zinc requirements

Zinc is an essential micronutrient in fish that plays vital role in many biological functions. Optimal Zinc level is indispensable in fish feed due to its multifaceted roles specifically in growth, antioxidant capacity and overall aquaculture productivity. The impact of dietary supplementation with zinc methionine (ZM), zinc oxide nanoparticles (ZNPs) and zinc sulfate (ZS) was assessed in juvenile Cyprinus carpio. Fish were fed a basal diet (Control), ZM, ZNPs, and ZS based diets at levels of 10, 20, 30, and 40 mg/kg for 90 days. ZNPs at 20 mg/kg exhibited the maximum weight gain (137.46 ± 1.74 %) and specific growth rate (1.44 ± 0.01 %/day), with lowest feed conversion ratio (1.75 ± 0.021) compared to the ZM and ZS diet groups. Fish fed 20 mg/kg ZNPs showed significantly higher superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) activity, along with reduced liver thiobarbituric acid reactive substances (TBARS). Glucose level was lower in ZNPs groups as compared to other zinc sources, while cortisol levels decreased dose-dependently (p < 0.001). The highest protein level was observed in fish fed 20 mg/kg ZNPs. Serum and muscle zinc concentrations increased in dose dependent manner in the all zinc supplemented dietary groups. Optimal dietary zinc levels were identified for ZM (30.95–35.29 mg/kg), ZNPs (24.13–27.70 mg/kg), and ZS (30.15–33.37 mg/kg) based on growth and health markers. In conclusion, ZNPs improved growth performance, antioxidant capacity, and overall health in C. carpio, making it a promising alternative to traditional zinc supplements.