Abstract: 5 semi -purified diets containing graded levels of protein ranging from 44. 64% to 57.69% formulated with casein and fish meal as protein sources were fed to Hexagrammos otakii with initial body weight of （70. 12 ± 1.92） g held in fiberglass tanks with triplication at water temperature of （ 19 ± 0.5 ） for 7 weeks. The results showed that there were significantly higher weight gain, specific growth rate （ SGR）, feed efficiency and protein efficiency ratio （PER） in the fish fed the test diets containing 50. 94% and 53.62% crude protein in dry matter （P 〈0. 05） than those in the fish fed the other diets. Based on quadratic model regression analysis of SGR and PER it was found that the optimal protein requirements were 51.9% and 51.08% of dry diet, respectively. There was no significant effect of dietary protein levels on body moisture, protein and ash （P 〉 0. 05）. However the fish had low body lipid （P 〈 0. 05） when they were fed the two diets containing higher levels of dietary protein at the end of the feeding trial .
2008, Vol. 23 
