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.