The primary aim of the current study was to analyze and to find out the effectiveness of probiotic bacteria (Lactobacillus plantarum andBacillus megaterium) on growth performance and immuno response of Catla catla. Growth parameters like final weight, weight gain, specific growth rate, survival rate, feed intake and protein efficiency ratio were increased among Catla catla were which fed with a diet containing L.plantarum. The combined effect of selected probiotic bacteria is shows significant level of the protein content when compared with control as well as single probiotic bacteria feed. L.plantarum gave larger inhibition zone (4 cm) than B.megaterium (1.8 cm). From the present study L.plantarum had a probiotic effect in vitro and in vivo against Aeromonas hydrophila, while B.megaterium had a probiotic effect in vitro and it small extinct in the in vivo. The Red blood cell levels were gradually decreased in all treatments (T1, T2 andT3). But in the all controls (C1, C2 andC3) the RBC values were gradually increased. White blood cell values are decreased in T1, T2 andT3 treatments and controls C1, C2 andC3 there is no much differences/changes. The plasma total proteins showed significantly decreased in fish fed with diet containing L.plantarum and mixture of L.plantarum andB.megaterium. The above results show that the probiotic bacteria can eliminate the pathogenic bacteria which cause disease in fish and other aquaculture organism.