Infection Experiments with Edwardsiella tarda in the Japanese Flounder

Abstract

Infection experiments in the Japanese flounder (Paralichthys olivaceus) with Edwardsiella tarda were conducted by intramuscular injection, intraperitoneal injection, immersion, and oral administration methods. Mortalities were produced by all the methods tested, LD₅₀ being determined as 7.1×10¹CFU/fish by intramuscular injection, 1.7×10²CFU/fish by intraperitoneal injection, 3.6 ×10⁶CFU/ml by immersion, and 1.3×10⁶CFU/fish by oral administration. These results show that the Japanese flounder has high susceptibility to E.. tarda. Mortalities continuously occurred during the observation period of 15 or 20 days showing a chronic nature of the disease.