Effect of Probiotic Bacteria Culture on Pathogenic Bacteria from Fresh Water Fish Oreochromis Mossambicus

Fish diseases are one of the major problems in fresh water biota. There is an urgent need in aquaculture to develop microbial control strategies, since diseases epidemics are recognized as important constraints to aquaculture production, trade and the development of antibiotic resistance has become a matter of growing concern. In this study, we evaluated the tilapia fish (Oreochromis mossambicus) microbial population and their bio efficacy on aquaculture. Totally 2 rectangular tanks was each stacked with 15 infected fish averaging 22.80 ± 1.0 g and those were fed at maintenance level for 15 days prior to the experiments. About 29 Lactobacillus isolates were isolated from O. mossambicus. Among the 29 Lactobacillus isolates, the isolate RR17 was selected for further study. Based on morphological, biochemical characteristics, the isolates were identified as Lactobacillus sp. The pathogens were isolated, characterized and identified as Aeromonas sp., Vibrio sp., Escherichia coli, Pseudomonas sp. and Salmonella shigella. The isolate Lactobacillus sp. RR17 was screened for antagonistic activity against all the pathogens by agar diffusion assay. The isolate Lactobacillus sp. RR17 showed significant antagonistic activity against only three pathogens. The isolate was multiplied and the fish feed was supplemented with the isolate Lactobacillus sp. RR17. The results revealed that the size and weight of the fish drastically increased when compare to control fish. Thus, the present study clearly demonstrated that the Lactobacillus isolates could be used successfully as probiotic bacteria in aquaculture.