It is аnalyzed data of the muscle contaminations of the cyprinid fish by metacercaria trematodes: Opisthorchis felineus and Rhipidocotyle campanula. It is noted that the both parasites found in the same species of fishes in the river Biryusa and In case of insufficient experience can incorrectly identified. It is concluded that the opisthorchiasis center of in the Taischet district of Irkutsk region is not practically studied. At this time there is an information of the fish infection from sites belonging to 8 (of 31) of Taishet distric rural municipalities: Biryussinskoe, Borisovskoe, Dzhoginskoe, Zarechenskoe, Kvitokskoe, Schitkinskoe Nizhnezaimskoe and the Polovino-Cheremkhovoskoe). Requires a systematic yearly, including seasonal study of the opisthorchiasis center in order to determine its boundaries and to study the status at all levels of the parasitic system of Opisthorchis felineus.