Abstract
Two hundred and seventy monosex males Nile Tilapia (Oreochromis niloticus) with an average body weight of 16.65±0.2 g/fish were used to investigate the effect of dietary replacement of inorganic iron by different levels of Fe-NPs on growth performance, body composition and health status of A. hydrophila challenged Nile tilapia fish. Fish maintained on 30% protein level, Six different experimental diets supplemented with 0.0 (T1), 85.0 mg inorganic Fe/kg (T2) and 85.0, 63.75, 42.5 and 21.25mg Fe-NPs/kg (T3-T5) were fed to triplicates groups of fish. It was found that the final body weight, weight gain, SGR, FCR and PER were significantly improved in the fish fed on the iron-supplemented diets compared to those fed on the iron-deficient diet (T1). Blood pictures and serum biochemical were significantly increased before and after A. hydrophila infection in the iron-supplemented groups compared to the iron-deficient diet group. The dietary administration of iron NPs improved the antioxidant enzymatic activities (CAT and TAC) irrespective of the different iron sources in the basal diet. Moreover, it was observed that the diets containing 63.75 and 42.5 mg/kg of Fe-NPs exhibited the best survival rate compared to the other groups.

Key words: Nile tilapia- Nano iron- Growth performance- Body composition- Immune response