This experiment was conducted to confirm the relationship between dietary lipid levels and n-3 highly unsaturated fatty acids (n-3HUFA) contents and to determine a suitable n-3HUFA content in diet for fingerlings of red sea bream by feeding them with various white fish meal-casein diets containing different amounts of lipid (5-20%) and n-3HUFA (1.2-4.2%) at a fixed protein level of 52%.
At a level of 10% lipid, growth was lowered as n-3HUFA content in the diet increased, and the lowest feed performances were obtained in fish fed on a diet containing 3.7% n-3HUFA. On the other hand, at 15% lipid, the growth and feed efficiency were not affected by elevation of die-tary n-3HUFA content, reaching a maximum at 3.7% n-3HUFA. Furthermore, at a level of 20% lipid, growth rate and feed efficiency were also improved as the n-3HUFA content increased, recording high in diets containing n-3HUFA above 3.7%. These results clearly indicated that the n-3HUFA content in diet should be increased in proportion to dietary lipid levels to obtain maxi-mum growth. Moreover, the best growth and feed efficiency were obtained in fish fed on a diet with 15% lipid when n-3HUFA was adjusted to the level mentioned above.
Thus, the growth of red sea bream fingerlings was found to be greatly influenced by dietary n-3HUFA levels, a suitable level being approximately 20% in dietary lipid regardless of lipid levels.