INFECTION EXPERIMENTS WITH EDWARDSIELLA-T ARDA IN THE JAPANESE FLOUNDER

Infection experiments in the Japanese flounder (Paralichthys olivaceus ) with Edwardsiella tarda were conducted by intramuscular injection, i ntraperitoneal injection, immersion, and oral administration methods. Mortalities were produced by all the methods tested, LD(50) being dete rmined as 7.1 x 10(1) CFU/fish by intramuscular injection, 1.7 x 10(2) CFU/fish by intraperitoneal injection, 3.6 x 10(6) CFU/ml by immersio n, and 1.3 x 10(6) CFU/fish by oral administration. These results show that the Japanese Rounder has high susceptibility to E. tarda. Mortal ities continuously occurred during the observation period of 15 or 20 days showing a chronic nature of the disease.