Atypical Aeromonas salmonicida Isolated from Cultured Shotted Halibut

A disease occurred among 0 and 1-year-old shotted halibut, Eopsetta grigorjewi which were hatcheryreared and cultured for releasing, and 3, 4 and 5-year-old shotted halibut which were cultured as brood stocks. External signs were redness of the head and the body surface, and erosion of the lip. Bacteria were isolated from the kidney, spleen or brain of the diseased fish. The isolates were identified as atypical Aeromonas salmonicida by the biochemical and serological properties. Intramuscular injection of an isolate into Japanese flounder, Paralichthys olivaceus produced signs similar to those of the spontaneously diseased shotted halibut and caused death.