In order to determine the optimal requirement of dietary lipid for butterfish (Scatophagus argus),5 isonitrogenous diets containing 3%,6%,9%,12%,15% lipid levels (F1-F5) were prepared with fish oil as lipid source,to feed the butterfish juveniles (average body weight 4.3 g) for 8 weeks in the floating cages in the sea,and the growth performance,immunity and antioxidant indexes and endogenous digestive enzyme activities of the fish were determined.The results showed that both the weight gain rate (WGR) and specific growth rate (SGR) reached the maximum values in F3 group with 9% dietary lipid level but showed no significant difference with F4 and F5 groups.Moreover,the maximum value of the protein efficiency rate (PER) was observed in F4 group with 12% dietary lipid level,and there was no significant difference among the F2-F5 groups with 6%-15% dietary lipid levels.However,the feed conversion ratio (FCR) displayed an opposite tendency,with the minimum value was observed in F3 group with 9% dietary lipid level and no significant difference was observed among the F2-F5 groups.The hepatosomatic index (HSI) increased with the increment of the dietary lipid levels and was significantly higher in F5 group with 15% dietary lipid level than those in F1 and F2 groups.The dietary lipid levels also significantly affected the contents of crude lipid,protein,ash and moisture of fish body.When the dietary lipid level was 9%,the fish exhibited higher lipase activities in the stomach and intestine and better immunity and antioxidant indexes in the intestine and liver than the other groups.The regression analysis of dietary lipid levels with WGR or FCR was conducted separately by the curvilinear method and the results suggested that the optimal dietary lipid level is 8.6%-11.0% for juvenile butterfish.