The subject of this master thesis is to morphologically and molecularly characterize Ceratomyxa species (Myxozoa) found in clinid fish from the tip of South Africa. Molecular characterisation of those species was done based on SSU rDNA and morphological structure of those parasites was examined. It was determined whether some of morphologically identical parasites represent in fact, different species. Phylogenetic relationships between different species in connection with their natural habitats were analysed and a correlation between population structure of Ceratomyxa species and their host species was discussed.