A genus of the zoological class Myxosporea found as parasites in the muscle tissue of many species of marine and freshwater vertebrate fish. Many species of Kudoa secrete a proteolytic enzyme to form, at the least, unsightly white cysts in the flesh and, in extreme cases, to result in softening and liquefaction of the flesh. The cysts become very obvious if the fillet is smoked. Some species of Kudoa are specific to particular species of fish, but Kudoa thyrsites is known to infect some 20 or more species, including economically important species such as salmons - wild and farmed - and Pacific hake.