Lymphocystis is a viral disease among aquarium fish which starts off with small white bumps that can grow into cauliflower-like structures or form strings. These wart-like growths are hugely enlarged cells and this kind of excessive growth is called hypertrophy.


There is no specific treatment against Lymphocystis. To improve resistance to disease and to stimulate the immune system, we recommend using eSHa OPTIMA’s plant extracts for splendid water-quality and eSHa MINAROLL’s vitamins and mineral complex every day in the aquarium. This will aid your fish in resisting negative environmental influences.

Cause & life cycle

Lymphocystis is caused by a large size, double stranded DNA virus which belongs to the genus Lymphocystivirus and is part of the Iridoviridae family. Lymphocystis infects both freshwater and marine fish species. The disease occurs frequently in labyrinth fish (gourami, colisa lalia), cichlids (apistogramma, angel fish), marine amphiprion, butterflyfish and other fish species. The virus affects the connective tissue cells of fish skin and internal organs. After penetrating the host cell, the virus replicates in the cytoplasm and starts to cause structural changes, called the cytopathic effect, which occurs about 30 days after infection. The behavior of infected fish does not change, they continue to lead an active life, eat and do not separate themselves from the group.


What is Lymphocystis and what does it look like?

Virus-infected cells increase in size from a few thousand to even a hundred thousand times, reaching up to 2 mm in diameter. In the first stages, when only individual super-sized (hypertrophied) cells are visible on the body, Lymphocystis can be confused with diseases such as ‘Ich’ (an infectious disease caused by the pathogenic ciliate Ichthyophthirius multifiliis). In general though, these giant cells form clusters resembling bunches of grapes or raspberries. The virus can attack any area of the body, but most often is localized at the fin tips and the mouth, the areas most susceptible to injury. Minor inflammatory reactions may be observed around these clusters. If you take a scraping from the affected area of the fish, you can microscopically see round shaped hypertrophied cells, covered in a dense and smooth hyaline membrane.

Over time, the affected cells burst and the cytoplasm containing the virus enters the water, creating the risk of infecting other fish. Mass fish mortality from Lymphocystis is not observed, but affected fish can look unsightly. In extreme cases, hypertrophied tissue can block the mouth, and the fish will lose the ability to feed. In this case, you can try to remove the formation surgically.

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