An 8-week feeding trial was conducted to evaluate the effects of different dietary protein and carbohydrate levels on the nutritional composition and texture of dorsal muscle.Six experimental diets were formulated to contain two protein levels(41.0%,37.5%)and three carbohydrate levels(taking wheat flour as carbohydrate source,the content of wheat flour was 19%,24%,29%),named L1(19/41),L2(24/41),L3(29/41),L4(19/37.5),L5(24/37.5)and L6(29/37.5),respectively.Taking black sea bream as the test object fish[mean initial body weight was(9.95±0.22)g],at the end of feeding trial,dorsal muscle was sampled from each fish.Proximate and amino acid compositions,as well as histology and texture of dorsal muscle were analyzed.Results showed that crude protein,crude lipid and amino acid composition of dorsal muscle were not significantly affected by treatments(P>0.05)except contents of glutamic acid(Glu),alanine(Ala),leucine(Leu)and methionine(Met)(P<0.05).Besides,the interaction of dietary carbohydrate level and protein level has significantly affected hardness of dorsal muscle(P<0.05).When dietary protein level decreased,the hardness and the gumminess of dorsal muscle decreased significantly(P<0.05),while the resilience of that increased significantly(P<0.05).Among fish from groups of the same dietary protein level,increased dietary carbohydrate significantly affected the hardness and gumminess of dorsal muscle(P<0.05).Protein level decreased,the density of muscle fiber decreased(P<0.05).In conclusion,dietary carbohydrate and protein ratio has no significant effect on nutritional composition of dorsal muscle but affects a part of amino acids and its texture indexes significantly.