Abstract: Nile tilapia Oreochromis niloticus juveniles with body weight of (9.81±0.42) g were reared in 20 150L recirculating tanks at a rate of 15 individuals per tank and fed isonitrogenous and isolipid diets containing amylose-amylopectin ratios of 0.10 (diet 1), 0.24 (diet 2), 0.47 (diet 3), 0.76 (diet 4) and 0.98 (diet 5) at water temperature of 27.5~32℃ with four replicates over a 6-week period to evaluate the responses of growth and intestinal microbial fermentation to starch type. It was found that the fish fed diet 2 exhibited the maximal weight gain and feed efficiency, significantly higher than the fish fed diets 4 and diet 5 did, and the minimal performance in the fish fed diet 5. The number of intestinal bacteria Escherichia coli and Lactobacillus spp. was shown to be elevated as the dietary amylose-amylopectin ratio was increased. There was significantly higher digesta acetate concentration in the fish fed diet 5 than that in the fish in the other groups, and there was significantly higher digesta propionate value in the fish fed diet 3 that those in the fish fed diets 1, 4 and 5. However, no digesta butyrate was detected in digesta of the fish fed various diets. The fact that there was inconsistent relationship between growth and bacterial fermentation in the fish fed various dietary amylose-amylopectin ratios leads to further investigation to better understanding of starch metabolism associated with nutrient utilization in the fish.