In the present study 128 specimens from six species of fish including Copoeta copoeta gracilis, Neogobius fluviatilis, Carassius auratus, Chalcalbutnus chalcoides, Alburnoides bipunctatus and Pseudorasbora parva were collected from Shiroud River and were studied for infection to Digenea. In the study on intection to Digenea, four species were identified, namely: Posthodiplostomum cuticula and Clinostomum complanatum, Diplostomum spathaceum and Allocreadium sp. Clinostomum complanatum was the most abundance )( SE± of this parasite in C. c. gracilis (the most abundant host species) were 47.7% , 8.74 )36.1(± and 18.33 )18.2(± . In this study, variation of the prevalence, abundance, mean intensity with host sex and length group, effects of parasites on the host growth parameters will be considered and ecological indices including richness, dominance, similarity, diversity and equitability are discussed.
