Various parasite species were found in Carassius carassius including Diplostomum spathaceum, Dactylogyrus sp.,Gyrodactylus sp. Ichthyophthirius multifiliis and Trichodinia sp . They were found in four rivers in West Azerbaijan Province (North-Western Iran) . A total of 207 live Carassius carassius from four rivers including Aras (72) Zariyneh (42) Nazlo (58) and Barandoz (35) were studied. Parasitological surveys were carried out on gills and external organs. The results showed that Diplostomum spathaceum (70.83%) Dactylogyrus sp. (38.88%) Gyrodactylus sp. ) 22.22%) Ichthyophthirius multifiliis (48.61%) Trichodinia sp. (8.33%) Chilodonella sp. (12.50%) and Argulus sp. (76.19%) were found in fish from Aras Rive so that the result showed, Spathaceum (63.79%) Dactylogyrus sp. (36.20%) Gyrodactylus sp. (25.86%) Ichthyophthirius multifiliis (44.82%) Trichodinia sp. (18.96%) Chilodonella sp. (12.06%) and Argulus sp. (6.89%). Argulus prevalence was greater in Barandoz River while Chilodonella in Zariyneh rud River . In Barandoz River, Diplostomum spathaceum (65.71%) Dactylogyrus sp. (37.14%) Gyrodactylus sp. (22.85%) Ichthyophthirius multifiliis (31.42%) Trichodinia sp. (25.71%) Chilodonella sp. (8.57%) and Argulus sp. (5.71%) were reported, respectively. Finally, in Zariyneh rud river, the followings have been reported: Diplostomum spathaceum (76.19%) Dactylogyrus sp. (21.42%) Gyrodactylus sp. (14.28%) Ichthyophthirius multifiliis (52.38%) Trichodinia sp. (23.80%) Chilodonella sp. (14.28%) and Argulus sp. (7.14%). It should be noted that prevalence , intensity and host parasite relationship will be discussed in details in this article.