Aeromonas veronii biovar sobria associated with mortalities of riverine ayu Plecoglossus altivelis in the Tama River

Abstract

In July 2016, there were mortalities of riverine ayu Plecoglossus altivelis in a tributary of the Tama River, Japan. A Gram-negative, motile and short rod-shaped bacterium was dominantly isolated from all examined dead fish, and identified as Aeromonas veronii biovar sobria. Biochemical characteristics and gyrB sequence of the present strains differed from those of A. veronii strains from ayu in previous years. The present strains also caused higher mortalities to ayu than A. veronii strains previously isolated. These results indicate that the present mortalities of riverine ayu in the Tama River were caused by high pathogenic A. veronii biovar sobria.