Enteric redmouth disease, or simply redmouth disease is a bacterial infection of freshwater and marine fish caused by the pathogen Yersinia ruckeri. It is primarily found in rainbow trout (Oncorhynchus mykiss) and other cultured salmonids. The disease is characterized by subcutaneous hemorrhaging of the mouth, fins, and eyes. It is most commonly seen in fish farms with poor water quality. Redmouth disease was first discovered in Idaho rainbow trout in the 1950s.[1] The disease does not infect humans.[1]