Japanese sea bass ( Lateolabrax japonicus ) were fed by six diets for 8 weeks to study the effects of different diets on the growth, nutrient composition, fatty acids composition and serum biochemistry indexes of f ishes. Five formulated diets all contained about 9. 79% lipid content with different lipid sources: fish oil, mixture of f ish oil and corn oil ( 1. 34..1) , mixture of fish oil and soybean oil ( 1. 34..1) , the rest two formulated diets contained fish oil and more choline ( 100g..kg - 1 ) and carnitine ( 350mg..kg - 1 ) added respect ively. .. Iced trash fish.. ( Saurida tumbil ) were used as control diet . The results showed the tolerance to fat liver of Japanese sea bass was weak and the detrimental effects would be seen if f ishes were fed by a large quantity of .. iced trash f ish.. for long time. Different lipid sources made no significant difference on the growth of Japanese sea bass when its EFA requirements were met, but they could take some effects on the lipid deposit in f ishes. Choline and carnitine had some effects to reduce the lipid of the fish.