Abstract
During late autumn of 1970 till following early spring, an epizootic occurred among cultured crimson sea breams, Evynnis japonica, in a bay in Kachi Prefecture. The disease was characterized by large ulcerative lesions with hemorrhagic borders on the body surface(Fig.1). Generally a great number of bacteria were found in the blood of moribund fishes.
The causative organisms were gram-negative, nonsporing rods with polar flagella, and usually about 1.8×0.4μin size. On nutrient agar colonies developed within 24 hours at 25°C. They gave positive catalase and oxidase reaction, utilized glucose oxidatively in HUGH-LEIFSON'S medium and reduced nitrate to nitrite. The organisms produced diffusible fluorescin, and were positive to citrate utilization, and liquefaction of gelatin, and negative to indol production and methylred test.
On the basis of the above characteristics, the organism was identified as Pseudomonas fluorescens.
