Definition: Vibriosis is an enzootic disease of fish, recorded from all over the world. It is almost exclusively caused by halophilic vibrios of the species Vibrio anguillarum and rarely by Vibrio parahaemolyticus. It occurs among various fish species, predominantly in marine and brackish waters, and occasionally in fresh water. First described as red pest disease of eels. Now described as hemorrhagic lesions on the body surface of many marine fishes.