The bacterium strains were isolated from the gil-l rot disease of the European eel ( Anguilla anguilla) . The isolate was proven to be the pathogen of the disease. By challenge test and ident ified to be the Pseudomonas putida. The bacteria are Gram negat ive motive short rods. The Physiological and biochemical characteristics were following: Oxidase, catalase, utilization of sodium citrate, Arginine deydrolase positive, nitriates reduced to nitrites, ornithine decarboxylase, lysine decarboxylase, gelatinase, Urease, voges proskauer reaction negative. The bacterium is hightly sensitive to Norf loxacin, Tobramycin, Kanamycin and Gentamycin.