Large Mouth Bass Virus

Largemouth bass virus was first discovered in a largemouth bass caught from Lake Weir, Florida in 1991. It is the sole virus known to be lethal to largemouth bass, and has caused large die-offs in various locations. Since its discovery, the virus has been found in many Eastern states. Though it is more common in wild fish, infection of hatchery-raised fish has been reported.

It is difficult to determine whether or not an infected fish has the largemouth bass virus, because external symptoms are not always present. If fish do display symptoms, they may include loss of equilibrium, floating on the surface of the water, and internal lesions on the swim bladder.

Fish become infected with largemouth bass virus by contact with the water or by eating infected fish. It is not known if adult fish may infect their offspring.