A feeding trial was conducted to investigate the optimum dietary protein level for maximum growth of fingerling Zacco pachycephalus (Gunther). Brown fish meal was the primary protein source in the study. Eight experimental diets containing 7 to 56% protein with 370 kcal/100 g diet were fed to three replicate of 12 fishes (mean weight: 1.28g) for 8 weeks. Both percent weight gain and feed efficiency increased with increasing dietary protein levels up to 35%, but there were no significant differences (P>0.05) for protein levels from 35 to 56%. Protein efficiency ratio, productive protein value, hepatosomatic index and viscerosomatic index were inversely correlated with dietary protein level. Protein content of fish carcass increased with dietary protein levels up to 35%, while no significant difference was found in protein level higher than that. Carcass lipid content generally decreased with increasing dietary protein levels. Carcass moisture value exhibited a negative relationship to lipid content. The amount of 24 h postprandial accumulated ammonia excretion in Zacco