The bacterium causing enteric redmouth (ERM) and Aeromonas salmonicida were found to be equally pathogenic for fingerling Atlantic salmon (Salmo salar). Injection of 5 × 105 cells of ERM or A. salmonicida killed all salmon within 96 h. After a 30 min exposure to water-borne cells of the two test bacteria about one-half of the test salmon died within 14 days. Both ERM and A. salmonicida were transmitted horizontally. Results indicate that efforts should be made to prevent introduction of ERM into watersheds where Atlantic salmon occur.
