Nile tilapia Oreochromis niloticus with body weight of 80—100g were cultivated in a simulated aquatic micro-system and fed diets containing melamine at a dose of 10g/kg for 10 days,and then fed basal feed for 10 days at 23—28 ℃,to evaluate effects of dietary melamine on activities of catalase(CAT),superoxide dismutase(SOD),7-ethoxyresorufin-O-deethylase(EROD)and glutathione S-transferase(GST)in tilapia liver at various experimental times.These enzyme activities were shown to be significantly induced,with in...