Two isonitrogenous and isocaloric soybean meal basal diet and fish meal plus soybean meal diet were formulated as control diets.The soybean meal basal diet was supplemented with different levels of calcium salt of 2-hydroxy-4-(methylthio) butanoic acid(MHA-Ca)at 0.045%,0.090%,0.135%,and 0.180%,respectively.After eight weeks feeding,weight gain,length gain,feed conversion rate,and protein efficiency ratio of common carp were determined.Moisture,crude protein,crude lipid,and crude ash in white muscles of common carp were measured.The weight gain,length gain,and protein efficiency ratio of carps fed 0.135% MHA-Ca diet were significantly higher than those of fed soybean meal basal diets(P<0.05),but were not different from those fed fish meal diet.Feed efficiency(feed:gain ratio) of the 0.135% MHA-Ca group was significant lower than the soybean meal control group(P<0.01),and not different from the fish meal group (P>0.05).Compared to the soybean meal basal diet,diet supplemented with 0.090% and 0.135% MHA-Ca resulted in significant higher protein content in the white muscle(P<0.05),but it was not different from the fish meal diet(P>0.05).Dietary supplementation with different levels of MHA-Ca had no significant effect on the moisture, fat,and ash content in the white muscles of common carp relative to the soybean meal basal diet or fish meal diet(P>0.05).