Mass Mortality Caused by Pseudomonas anguilliseptica in the Pond-cultured Ayu Plecoglossus altivelis

Abstract

Pseudomonas anguilliseptica infections have not been reported in cultured ayu Plecoglossus altivelis in Japan since a few occurrences in the 1980s. ​In the spring of 2013, however, mass mortality was encountered at an ayu rearing facility in Akita Prefecture, Japan, and the causative agent was identified as P. anguilliseptica. ​In this study, biochemical characterizations and 16S rRNA gene sequences of the isolates from the present event were shown to be identical to previously reported isolates of P. anguilliseptica from ayu. ​LD₅₀ of the present isolate against ayu in the infection test was 1.7 × 10³ cfu/fish.