A 92week feeding trial was conducted to investigate effects of different dietary acid supplements on growth performance in juvenile hybrid tilapia Oreochromis niloticus ?O. aureus (average body weight was about 1. 9g) . 5 test diets were applied for triplicate tanks and 15 fish was stocked randomly in each tank. Feeding rate was6%ofwetbodyweight. Noacidsupplementwasaddedinbasaldietwhichwasappliedascontrol,0.3%of phosphoric acid , fumaric acid , citric acid , lactic acid were added in basal diet , respectively. The results showed that specific growth rate of fish fed diet with citric acid and lactic acid were significantly higher than those of fish fed basal diet and diet with fumaric acid ( P < 0. 05) . Feed efficiency in fish fed diets with phosphoric acid , lactic acid and citric acid was higher than that of fish fed basal diet , but differences were not significant ( P > 0. 05) . However , significantly higher feed efficiency was observed in fish fed diet with lactic acid than that of fish fed diet with fumaric acid ( P < 0. 05) . The content of body moisture in fish fed diet with lactic acid was significantly higher than that of fish fed diet with fumaric acid ( P < 0. 05) , while no significant differences were observed in whole body protein , lipid and ash among treatments ( P > 0. 05) . The activity of pepsin in fish fed diet with fumaric acid was significantly lower than those of fish fed with other diets. The intestinal amylase activities in fish fed diets with citric acid and lactic acid were significantly higher than that of fish fed basal diet ( P < 0. 05) . Significantly higher activities of hepatic lipogenetic enzymes were observed in fish fed diet with lactic acid and citric acid than those of fish fed other three diets ( P < 0. 05) . Accordingly , serum triglyceride concentration in fish fed diets with citric acid and lactic acid was increased significantly. The results suggested that 0. 3 % citric acid and lactic acid supplements can significantly improve growth performance in juvenile hybrid tilapia , while , fumaric acid supplement reduces feed utilization.