Posted by beth on 08 Nov, 2019

Lymphocystis is a chronic viral infection effecting susceptible fish resulting in the cauliflower or ward-like appearance of lesions on the afflicted fish’s fins and even the body. The size of these lesions can range from small irregular shaped spots as see in this blue hippo tang [not to be confused with ich],  to large wart-like growths.  Lymphocystis does not have to be a death sentence, however, and, in fact, it usually is not. Many fish with this condition may remain symptom-free; others will suffer significant disfigurement if the condition is not adequately addressed. Most typically, the effected fish will have minor spot symptoms that may come and go depending on adequacy of environment and food.Lymphocystis growths  seen on fish are not the virus itself, but the results of the virus. As the virus affects the connective tissues of the fish, cells are malformed, resulting in the production of skin cells that are grossly enlarged. This is the visible nodules seen on afflicted fish.

How is lymphocystis transmitted?

Lymphocystis is transmitted through direct contact of the fish with the virus in the water or by fish picking at the nodules on diseased fish. Water becomes a transmission medium when infected fish are introduced into the aquarium and the virus is released from the growths. The good news, however, is that the virus, while common, is not necessarily highly contagious. While one fish may be severely diseased, others in the aquaria never suffer ill-effects. The reason for this is because the virus affecting one fish may only be able to infect other same-species or closely related species of fish due to the DNA coding of any specific virus.TreatmentQuarantine in a well-established hospital tank while the growths are present is the safest way to avoid contamination of the aquaria. However, if the quarantine is not well-established and minimally appropriate for the fish, then the diseased fish will not do well in quarantine, and may worsen. Infected fish can also be addressed within the display, with [low] risk of infecting other fish and with higher risk of the originally afflicted fish being re-infected. Since the disease, like any virus, is opportunistic with a weakened host, fish that are mishandled, not receiving adequate nutrition or reside in poor living environments are much more susceptible then well-established, highly cared for fish.While the virus needs to run its course (approx. 1 month), effective treatment is fairly simple and involves basic husbandry practices that should be in place even without the presence or need to address lymphocystis.


Treatment and care entails providing your aquarium and fish with excellent water conditions, a good environment, a tranquil community setting, and quality nutrition that addresses the specific needs of the afflicted fish. The addition of quality supplements such as Zoecon and fresh garlic is likely to enhance the fish’s chances for full-recovery. There is no medicinal treatment and attempting to treat with a product could well worsen the situation, especially if medications are dumped into the display aquaria.As with any primary disease, secondary infections by bacteria, fungus or even parasites can result in weakened, sick fish. The hobbyist needs to be mindful of the development of secondary infections, which could be significantly more perilous to the fish than the lymphocystis and will require the removal of the fish to a quarantine for isolation and treatment.