Enteric Septicemia

Catfish with a bacterial head lesion caused by Edwardsiella ictaluri. (American Fisheries Society)

Edwardsiella ictaluri is the bacterium that causes enteric septicemia or "hole in the head disease" of channel catfish. The disease affects mainly farmed catfish, but infections have been reported in a limited number of other warm water species.

Fish infected with E. ictaluri display loss of appetite, hang almost vertically at the water surface and exhibit spiral swimming. Externally, there is hemorrhaging on the skin (especially near the mouth and throat), exophthalmia ("pop-eyes") and pale gills. In some cases infected individuals develop a characteristic open lesion or "hole" in the frontal bone between the eyes.

Edwardsiella ictaluri has limited ability to survive in water. Fish that survive outbreaks of this pathogen probably serve as reservoirs of infection.