Angel fish (Pterophyllum scalare) are popular aquarium pets. Unsightly growths are occasionally observed on the mandible or maxilla of adult fish. Affected fish remain normal in attitude and behavior and may even continue to spawn. As the size of the mass increases, however, feeding ability of the animal may be impaired resulting in deterioration of condition.

Similar growths have been observed in several species of cool water fish (Wolf, 1988) including walleye (Stizostedion vitreum vitreum), white sucker (Catostomus commerson), and Northern pike (Esox lucius). Type-C retrovirus particles have been associated with these neoplasms in each species; however, attempts to prove that the virus is the agent cause of the tumors have not been successful (Wolf, 1988).

Retrovirus particles have been identified in tissue surrounding tumors from angel fish using transmission election microscopy. Attempts to transmit tumors using cell-free filtrates have not succeeded and transmission between individual fish housed together has not been observed. New lesions have not occurred following surgical removal of tumors. The significance of retrovirus particles associated with these lesions is uncertain at the present time

References

1.  Wolf, K. 1988. Fish Viruses and Fish Viral Diseases. Cornell University Press, Ithica, NY. 476 pp.