Lymphocystis

Lymphocystis is a common viral disease of freshwater and saltwater fish. The virus that cause this disease belong to the genus Lymphocystivirus of the family Iridoviridae. Lymphocystis is a common viral disease of freshwater and saltwater fish. The virus that cause this disease belong to the genus Lymphocystivirus of the family Iridoviridae. Aquarists often come across this virus when their fish are stressed such as when put into a new environment and the virus is able to grow. The fish start growing small white pin-prick like growths on their fins or skin and this is often mistaken for infection by Ichthyophthirius multifiliis in the early stages. It soon clumps together to form a cauliflower-like growth on the skin, mouth, fins, and occasionally the gills. This virus appears to present itself as lesions at differing locations depending on the species of fish being attacked, often complicating initial diagnosis. Lesions at the base of the dorsal fin are common among freshwater species of Central American origin, most notably Herichthys carpintis; inside the mouth of Herichthys cyanoguttatus and Geophagus steindachneri; on the tail fin of koi, carp, and US native sunfish (Lepomis spp.); on the side flanks of walleye, sauger and flounder; on head or tail areas of common goldfish, and oranda variants.