An 8-week trial was conducted to investigate the effects of five carbon sources on the growth performance, intestinal biochemical parameters and water quality in the juvenile Megalobrama amblycephala by the principle of bio-floc technology(BFT).The carbon sources include starch(control), glucose, sucrose, sodium cyclamate, composite carbon(mixture of starch and glucose in proportion of 1:1).The juvenile M.amblycephala with initial body weight of(36.74±0.82)g were stocked into 15 indoor cement tanks(1 m×4 m×0.6 m)and fed commercial feed with daily normal feeding.At the initiation of the experiment, the fish were randomly chosen and sorted into 15 indoor cement tanks with 20 individuals per tank.Each experimental group was randomly assigned to triplicate tanks for a completely randomized design.The results of this study showed that bioflocs could effectively regulate water quality, as well as reduce ammonia and nitrite concentration.Final body weight, weight gain rate(WGR), specific growth rate(SGR)of glucose group were significantly higher than the other groups(P<0.05), while feed conversion ratio was significantly lower than the other groups(P<0.05).Furthermore, no significant differences(P>0.05)were observed for the survival rate and the body composition among all treatment groups.Intestine microstructure observation showed that there were some bioflocs in the brush border of intestine in juvenile M.amblycephal.The activities of protease and amylase of fish in the composite carbon group were significantly higher than control group, glucose group and sucrose group(P<0.05).The activities of superoxide dismutase and catalase of fish in the composite carbon group were 72.5% and 40.4%, which were significantly higher than those of control group, however, the malondialdehyde content was lower than that of control group(P<0.05).