A total of 150 cultured Nile tilapia (Oreochromis niloticus) fish were affected by the tail and fin rot disease were obtained. These fish were subjected to clinical, P.M. and bacteriological examination. The bacterial isolates were morophologically and biochemically related to Pseudomonas fluroscens & Pseudomonas anguilliseptica. Reisolation of both arganisms were recovered after the experimental infection of healthy live 0. niloticus by intraperitoneal route accompanied by high organic matter nearly revealing the some clinical signs and lesions. High organic matter is a major stress
factor for occurence of such dangerous disease. Besides, the antibiogram of the recovered isolates was attempted.