The high consumption of antibiotic in aquaculture for controlling fish disease lead to antibiotic resistance, so for improving this resistant against infectious disease it could be achieved by using of probiotics as an alternative strategy. Main objective of this study was to revealed the influence of some isolated probiotic bacteria as Bacillus spp and Lactobacillus spp on pathogenic bacteria which isolated from naturally infected Nile tilapia such as Aeromonas spp, Vibrio spp and Pseudomonas spp. Bioactivity of probiotic were measured by the diameter of inhibition zone on disc diffusion method, six probiotic were used for testing their ability to inhibited the growth of pathogenic bacteria, three of them were kindly provided and the other were isolated from pickles, fermentable milk and yogurt, respectively. The result indicates that Vibrio anguillrium recorded high prevalence pathogenic bacteria as 52% of isolates. The highest inhibition zone refers to Bacillus amyloliquefacien SW19 which range from (10-40 mm).