Aeromonas salmonicida is a pathogenic bacterium that severely impacts salmonid populations and other species. A. salmonicida is an etiological agent for furunculosis, a disease that causes sepsis, haemorrhages, muscle lesions, inflammation of the lower intestine, spleen enlargement, and death in freshwater fish populations. It is found worldwide with the exception of South America.
The major route of contamination is poor water quality; however, it can also be associated stress factors such as overcrowding, high temperatures, and trauma.
Spawning and smolting fish are prime victims of furunculosis due to their immunocompromised state of being.