Abstract: Objective: This study aimed to evaluate the effect of prebiotic from sweet potato (Ipomoea batatas L.) extract on the growth performance and health status of common carp (Cyprinus carpio ) before and after being infected by Aeromonas hydrophila. Materials and Methods: Prebiotic was supplemented through feed (0.5, 1 and 2% v/w) for 30 days. The parameters observed during prebiotic supplementation included the populations of the dominant bacterial species in the intestines, digestive enzymes activity, growth performance and immune responses of the fish. On day 32, a challenge test using the pathogenic bacteria A. hydrophila was carried out and fish resistance was determined by counting the survival rate of the fish at day 45. Results: Feed containing prebiotic supplementation at a dose of 2% showed a significant effect (p<0.05) on Total Viable Bacterial Count (TVBC) in the fish intestines and on protease activity and resulted in the best value for daily growth rate and feed conversion ratio (p<0.05) when compared with the control and other treatment groups. The predominant bacteria growing in the fish intestines were identified as Bacillus pumilus, Staphylococcus kloosii, Staphylococcus hominis and Aeromonas veronii. At the end of the feeding trial with prebiotic supplementation, the values of total leukocytes and phagocytic activities in the fish receiving 2% prebiotic were higher than controls. The survival rates of common carp after the challenge test in the 1 and 2% prebiotic treatments groups were 87.5 and 100%, respectively, while that of fish without prebiotic supplementation was only 50%. Conclusion: These results indicate that prebiotic supplementation for common carp has positive effects on the growth performance and health status of common carp infected by A. hydrophila and the best result was obtained with a 2% prebiotic supplementation.