Abstract
The Potamotrygonidae is the family inside Chondrichthyes class exclusively from freshwater and are distributed in the most river basins that have drainage to the Atlantic Ocean, such as Amazônas-Orinoco, Paraguay-Paraná, Uruguay and Parnaíba river basins. The Myxozoa are obligatory cnidarian parasites divided into two classes: Malacosporea and Myxosporea. More than 2400 species are includ…