In order to determine the concentration of the antibodies against the pathogenic Vibrio anguillarum, three hundred blood samples were taken from 9-12 month old cultured rainbow trout (Oncorhynchus mykiss) in 4 farms in the north and west region of Fars Province, which had been exposed to this bacteria. An indirect ELISA was employed to examine the serum. Using soluble antigen (SA) indicated that 54% of the examined blood samples contained antibodies against Vibrio anguillarum, while by using whole cell antigen (WCB) only 53% of samples were found to be seriopositive. The highest seriopositivity rate (83%) was observed in farm #2, where clinical signs of vibriosis also occurred. This study revealed that Rainbow trouts fed on raw marine fish meal powder are more exposed to V. anguillarum. Vibriosis in cultured Rainbow trout in Iranian inland freshwater farms is also discussed in this paper......
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