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 …bony fish as a rule have a marked tendency to be flattened in a vertical direction…. It was natural, therefore, that when the ancestors of [flatfish] took to the sea bottom, they should have lain on one "side"…. But this raised the problem that one eye was always looking down into the sand and was effectively useless. In evolution this problem was solved by the lower eye ‘moving’ round to the upper side. Flatfish is considered a Whitefish because of the high concentration of oils within its liver. Its lean flesh makes for a unique flavor that differs from species