Eleutheronema tetradactylum is one of high economic farmed fish in Taiwan and is susceptible to bacterial diseases due to improper management or poor culture environment. In order to investigate cause of diseases and improve the disease resistance of fish, this study screens the gut microbiota and the ways to improve the immunity of fish. The results showed that members of Vibrio and Photobacteria dominated the microbial community in all sampling fish. Furthermore, E. tetradactylum were fed with diets containing 3% garlic and turmeric, respectively, for 4 weeks. The results showed that the total number of bacteria in the intestine decreased significantly (p<0.05), and also increased the activity of serum lysozyme and superoxide dismutase, and effectively antagonized streptococcal infection with the disease resistance increased by 64% (p<0.01) and 55%, respectively.