The Caspian frisian roach (Rutilus frisii kutum), economically a very important fish species in Iran, is propagated in fishponds, reared into the rivers in fingerling size and then harvested from the Caspian Sea in adult stage. We found six monogenean parasites on the Caspian frisian roach including five Dactylogyrus spp. on fingerlings cultured in fishponds and rivers and two Dactylogyrus spp. on wild adult specimens living in Caspian Sea. With the exception of D. frisii that proved to be the most common monogenean and found a good milieu for its development both in flowing rivers and in Caspian Sea, the other parasites occurred either in Caspian Sea (D. nybelini) or in freshwater (D. haplogonus, D. rarissimus, D. suecicus, D. turaliensis). The objectives of present research work are to clear the sources of infection of Caspian frisian roach fingerlings to monogenean parasites and to recommend approaches for the improvement of pond technology in order to diminish the intensity of parasites without having to use high amounts of organophosphate insecticide in ponds.