An ichthyoparasitological study on 166 fishes, belonging to Poecilia reticulata Peters, 1859 (Poeciliidae), Rhamdia quelen (Quoy & Gaimard, 1824) (Pimelodidae) and Hypostomus ancistroides (Ihering, 1911) (Loricariidae) in tributary streams of the Pirapó River, located in and around urban city of Maringá, Paraná State, Brazil. The research aimed to recognize the endoparasite community of fishes analyzed, as well as to improve the knowledge about host/parasite relationships. We analyzed the correlation between the total length of the fish with levels of parasitism (prevalence, abundance). Due to the existence of sexual dimorphism in the species P. reticulata, we investigated the possible influence of sex of this fish on parasitism. In addition, we also analyzed the body surface and nostril for ectoparasites studies. There were no metazoan parasites on the body surface and nostril of...