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...

Parasitism was observed in 72.7% of 44 specimens of Metynnis lippincottianus (Cope, 1870) (Characidae) caught in the Upper Paraná River floodplain, Brazil. One species of digenean, Dadayus pacupeva Lacerda, Takemoto & Pavanelli, 2003, and four species of nematodes, Spinoxyuris oxydoras Peter, 1994, Contracaecum sp. Railliet & Henry, 1912 (larval stage), Procamallanus (Spirocamallanus) inopinatus Travassos, Artigas & Pereira, 1928 and Raphidascaris (Sprentascaris) mahnerti Petter & Cassone, 1984 were identified. The prevalence of D. pacupeva was correlated with the host's standard length. Correlations between the host's standard length and the abundance of S. oxydoras, P. (S.) inopinatus and D. pacupeva were observed. In addition, fish length was correlated with the diversity of parasites. D. pacupeva and S. oxydoras had their abundances influenced by the host's gonadal m...