Lymphocystivirus cause mass mortality events like megalocytiviruses and ranaviruses, fish with lymphocystis exhibit grossly visible papilloma-like skin lesions which substantially reduce their commercial value. No vaccines are currently available for lymphocystis viruses. Group: dsDNA The genus "Lymphocystivirus" has only one species: "Lymphocystis disease virus 1" (LCDV-1), but Lymphocystis disease virus 2 (LCD-2) is another virus that has been proposed as a second member. LCDV-1 infects European flounder "Platichthys flesus" and European plaice ("Pleuronectes platessa"). LCDV-2 infects the common dab ("Limanda limanda"). A third species Lymphocystis disease virus C has also been proposed based on the relative lack of sequence similarity of
Flatfish be a valid species in its own right. Flatfishes are found in oceans worldwide, ranging from the Arctic, through the tropics, to Antarctica. Most species are found in depths between 0 and , but a few have been recorded from depths in excess of . None have been confirmed from the abyssal or hadal zones. An observation of a flatfish from the Bathyscaphe Trieste at the bottom of the Mariana Trench at a depth of almost has been questioned by fish experts, and recent authorities do not recognize it as valid. Among the deepwater species, "Symphurus thermophilus" lives in congregating