Abstract:The present study was performed to investigate the requirement of lipid for grow-out grouper. Fish (initial body weight 278.5 g) were fed isonitrogenous diets containing five graded lipid levels(7.07%, 9.92%,12.92%,15.95% and 19.04%) of fish oil and soybean lecithin for 10 weeks. The results showed that: Weight gain rate, specific growth rate and protein efficiency ratio significantly increased, then decreased (P<0.05) with increased dietary lipid levels. Feed conversion ratio showed an opposite trend with weight gain rate. Survival of treatments were not significantly affected by the dietary lipid levels(P>0.05). Whole body and muscle crude lipid content first gradually increased, then stabilized and whole body ash gradually decreased with the dietary lipid level increased. Moisture and crude protein in whole body and moisture, crude protein and ash in muscle were not affected by dietary lipid levels (P>0.05). With increased dietary lipid levels, condition factor and viscerosomatic index gradually increased and then stabilized and hepatosomatic index gradually increased. Plasma glucose, triglyceride, total cholesterol and high density lipoprotein cholesterol levels significantly increased with increased dietary lipid levels (P<0.05), and total protein, low density lipoprotein cholesterol decreased significantly (P<0.05). With increased dietary lipid levels, the hepatic lipase, lipoproteinesterase and malic dehydrogenase activity gradually decreased, but lactate dehydrogenase activity gradually increased. Alkaline phosphatase, superoxide dismutase, lysozyme activities first increased, then stabilized with increased dietary lipid levels and acid phosphatase vitality significantly decreased (P<0.05). On the basis of specific growth rate, the optimum dietary lipid level, determined by second-order polynomial regression analysis is 14.44% for grow-out Epinephelus coioides.