The Myxosporidian Fauna of Some Fresh Water and Marine Fishes

Myxosporidia are highly successful sporozoan parasites of fishes. Although a few species have been described from other cold-blooded vertebrates, fishes are the characteristic hosts and harbor over 90% of the known species. In all localities in which a survey has been undertaken the Myxosporidia have proved to be common. This is equally true of fresh water and marine habitats. Although each species inhabits a particular host organ, the group as a whole have been recovered from the lumina or the tissues of nearly every organ in the body cavity, as well as the muscular, skeletal and nervous tissues and the gills, fins and integument. They may be divided into two categories, the histozoic species which dwell in the tissues of the host, and the coelozoic species, which live in the lumina of various hollow organs. They are never intracellular, and have not been found in the lumen of the alimentary tract