The objectives of the present study were to evaluate the probiotic potential of Bacillus sp isolated from the gut of Anabas testudineus. Study reveals the antagonistic effect of the Bacilli against Aeromonas Hydrophila and Vibrio harveyi and protective effect and survival rate of Carassius auratus and Xiphophorus maculates. The Bacilli was incorporated to commercial fish diet with 41% crude protein to evaluate their effect on the growth performance in rohu (Labeo rohita.). One hundred and sixty rohu fingerlings with an average body weight of 6.10 g per fish were equally divided into two treatments of four replicates. T1-T4 was given basal diet (control), T5-T8 with Bacillus sp (initial number of 107 cells g diet-1). The experimental period was 60 days. The best growth rate, feed utilization and survival rate were noticed in treated group. Probiotics Bacillus sp has significantly enhanced fish growth and health, indicating the potential use of indigenous fish guts bacteria as feed probiotic in aquaculture.