Viral Infection (Lymphocystis) in Fish

By PetMD Editorial on Jul. 2, 2008

Lymphocystis disease is a common viral infection which affects the skin and fins of saltwater and freshwater fish. Although it is serious, it does not cause any health problems; the disease only disfigures the fish.

Fishes kept in aquariums or outside in ponds are both susceptible to Lymphocystis disease. The painted glassfish is the most prone aquarium fish to contract this infection.

Symptoms and Types

The viral infection causes growths on the skin or fins, which look similar to cauliflowers.

The Lymphocystis disease does not pose any health problem to the fish, but the growths may make the animal less aesthetically pleasing.


A microscopic examination of the skin tissue is done to properly diagnose the viral infection.


Once Lymphocystis disease has been diagnosed, the veterinarian may recommend to not treat the fish. This is because the infection is not terminal. However, antiviral medication is sometimes prescribed, but it rarely cures the disease.

Featured Image: Chernetska

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