Lymphocystis disease virus is a type of virus that primarily affects fish, causing a condition known as lymphocystis disease. This disease is characterized by the formation of large, wart-like growths on the skin, fins, and gills of infected fish. It is most commonly found in freshwater and marine species, particularly in stressed or overcrowded environments. The virus is transmitted through direct contact between fish or contaminated water. While lymphocystis disease is not usually fatal, it can lead to secondary infections and affect the overall health of the fish. Proper management of water quality and fish populations can help reduce the risk of infection.