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.