US Fish & Wildlife Service


Date of this Version



Published by UNITED STATES DEPARTMENT OF THE INTERIOR Fish and Wildlife Service


Enteric redmouth disease (ERM) is a systemic bacterial infection of fishes, but is known principally for its occurrence in rainbow trout, Oncorhynchus mykiss. It was first reported in the 1950's in Idaho rainbow trout and described by Rucker (1966). In recognition of that first description, the causal organism was named Yersinia ruckeri by Ewing et al. (1978).