All available literature and perennial the author’s own fees of Kudoa genus myxosporeans of the world fauna fish have been analyzed. The specificity of these parasites, their site of infection in the body of the host, distribution in various reservoirs of our planet have been considered. Pathogenic species of myxosporeans of the genus Kudoa, parasitizing in valuable food species of fish in the World Ocean and damaging to the fisheries and mariculture have been listed. The negative influence of these parasites on the host organism at the organismic, tissue and biochemical level has been considered. Infection rates and seasonal changes for some fish species and the dependence of infection on their sex have been given. The symptoms of kudoosis in wild nature and mariculture have been described. Activities aimed at reducing the damage caused by Multivalvulida myxosporeans have been considered.