Effects of dietary dextrin at inclusion levels of 14.7 %, 20.7 %, 26.7 %, 32.7 % and 38.7 % on growth performance, feed utilization, biochemical composition, digestive enzyme activity, antioxidant capacity and tissue structure of Onychostoma macrolepis (1.78 +/- 0.10 g) was evaluated, the trial was conducted for 56-day. The results revealed that final body mass, weight gain and protein efficiency ratio were the highest in the 26.7% group, while feed conversion ratio (FCR) was the opposite. The optimal values of FCR and specific growth rate (SGR) were 25.27 % and 25.67 % respectively based on the quadratic regression analysis. The hepatopancreas trypsin activity was the lowest in the 32.7 % group (P<0.05), while the lipase activity in the 14.7 %, 20.7 %, and 26.7 % groups were higher than remaining groups (P<0.05), however, the amylase activity was not affected (P>0.05). Only the crude protein of whole fish was affected, its content was the highest in the 32.7 % group. Hepatopancreas and muscle glycogen were the highest in the 26.7 % group (P<0.05). Combined with the systematic clustering average method was found that MUFA and SFA in hepatopancreas increased, and n-6 PUFA and MUFA in muscle and MUFA in abdominal fat decreased with dextrin levels. The hepatopancreas glutathione peroxidase activity in the 32.7 % group was the lowest and catalase activity in the 20.7 % group was the highest (P<0.05), total superoxide dismutase activities in the 14.7 %, 20.7 % and 26.7 % groups were significantly higher than remaining groups (P<0.05), and malonaldehyde content in 38.7 % group reached the highest (P<0.05). Hepatopancreas exhibited severe vacuolation in the 32.7 % group, and intestinal villi were the longest in the 26.7 % group (P<0.05). In summary, based on FCR and SGR, the optimal dextrin levels in Onychostoma macrolepis feed were 25.27 % and 25.67 % respectively. When having good growth and not negatively affecting health status, the recommended addition levels of dextrin in feed were 20.7-26.7 %.
