ABSTRACT

Eels contract the same types of bacterial diseases as do other warmwater fishes; two infectious diseases, "edwardsiellosis", also known as "hepatonephritis", and "red spot disease" seem to have a greater affinity for cultured eels than for other species of fish. The causative agent of edwardsiellosis is Edwardsiella tarda (E. tarda) and is the same organism that was called Paracolobacterum anguillimortiferum by Wakabayashi and Egusa. Clinical signs of E. tarda infections differ slightly between locales and among different fish species. The significance of E. tarda depends largely on the fish species affected and the presence of environmental stressors. In Taiwan and Japan it is one of the most serious bacterial diseases of cultured eels. Red spot disease of eels is a mild to serious bacterial infection of cultured eels. The disease, known as Sekiten-byo in Japan, is caused by Pseudomonas anguilliseptica. Red spot disease of eels is diagnosed by isolation of P. anguilliseptica from internal organs.