Fish diseases and parasites
（重定向自Fish diseases）
![This gizzard shad has VHS, a deadly infectious disease which causes bleeding. It afflicts over 50 species of freshwater and marine fish in the northern hemisphere.[1]This flatfish Limanda limanda has an outgrowth called a xenoma. It is caused by a microsporidian fungal parasite in its intestines.[2]](/Images/godic/202501/13/VHS1857.png")
![](/Images/godic/202501/13/Glugea_stephani1857.jpg")
![A veterinarian gives an injection to a goldfish](/Images/godic/202501/13/Vet_goldfish1857.jpg")
![The isopod Anilocra gigantea parasitising the snapper Pristipomoides filamentosusCymothoa exigua is a parasitic crustacean which enters a fish through its gills and destroys the fish's tongue.[8]](/Images/godic/202501/13/lossy-page1-274px-Anilocra_gigantea_on_Pristipomoides_filamentosus.tif1857.jpg")
Like humans and other animals, fish suffer from diseases and parasites. Fish defences against disease are specific and non-specific. Non-specific defences include skin and scales, as well as the mucus layer secreted by the epidermis that traps microorganisms and inhibits their growth. If pathogens breach these defences, fish can develop inflammatory responses that increase the flow of blood to infected areas and deliver white blood cells that attempt to destroy the pathogens.