Preferences of the Myxosporeans of genus <i>Kudoa</i> Meglitch, 1947 of the world’s fauna fishes living at certain depths

This paper provides the first information on the possible occurrence of myxosporeans of the genus Kudoa in fish of the World Ocean and, in several individual cases, in associated freshwater bodies at different depths. For the first time, an analysis of the theoretically assumed association of Kudoa to different depths of habitat of their fish hosts of the World fauna is given. It was revealed that in the shelf zones adjacent to the shores, all species of myxosporeans of the genus Kudoa can be found, of which 90 species (70.8% of the total) are found exclusively in the shelf zone, and the hosts of 50 species of Kudoa (39.4%) live in its shallowest part (up to 50 m). At depths from the shelf to 500 and 1000 meters, 16 species (12.6%) and 14 species (11%) of this genus can be found, respectively. At depths of up to 1500 and 3000 m, theoretically, from 1 to 3 species of Kudoa can be found, which is from 0.8 to 2.4% of all known representatives of these parasites.