en fish disease fish disease پژوهشي Orginal research papers A survey on myxosporean parasites of freshwater fishes from Mesopotamian part of Iran (south western part of the country, Khuzestan Province) was carried out. Some 280 individuals belonging to 14 different species were examined the prevalence of myxosporean parasites, morphology of the spores, plasmodial development, the infective site, and characteristics of the cyst location using the histological approach. The collected parasites were as follows:<br> <em>Myxobolus presicus, M. karuni, M. bulbocordis, M. nodulointestinalis, M. iraanicus, M. mesopotamiae, M. shadgani, M. sharpeyi, M. molnari</em> and <em>M. mokayeri</em>. <em>Barbus</em> <em>sharpeyi</em> and <em>B. grypus</em>, economically important fishe, were infected by six and four myxosporean parasites respectively. All of the studied cases of infection were observed in the natural waters. Mesopotamian, Myxosporean, Myxobolus, Barbus, Iran 35 46 http://jifro.ir/browse.php?a_code=A-10-41-3&slc_lang=en&sid=1 M. Masoumian 100319475328460024598 100319475328460024598 Yes J. Pazooki 100319475328460024599 100319475328460024599 No