First isolation and identification of Vibrio vulnificus (biotype 2) from cultured beluga, Huso huso in Iran

By decreasing of sturgeon stocks in the Caspian Sea, the culture of different sturgeon species especially Huso huso was increased in Iran. Under stress conditions sturgeon can easily be infected by several opportunistic pathogens. In June 2011, mortality happened in 25-28°C water temperature, in one of the most important cultured sturgeon farms in Mazandaran province in the north of Iran. The mortality rate was 15%. The first clinical signs in moribund fish were lethargy and anorexia. A total of 20 moribund fish was transferred to a central laboratory for more bacteriological examination. Clinical signs including several deep ulcers on body surface, around the head, under operculum and the base of the pectoral fins, hemorrhage around of the anus, operculum, necrosis of the base of the pectoral fin and paleness gill was observed in moribund fish. The main internal signs were hepatomegally and spleenomegally, liquid accumulation in the intestine and diffuse visceral hemorrhage. The results of morphology and microscopic characterizations and also biochemical tests indicated that Vibrio vulnificus (biotype 2) was the etiological agent of mortality in infected fish. This study was the first report of V. vulnificus in cultured Huso huso in Iran.