New records and prevalence of metazoan parasites of fish in the southeastern Brazilian region.

Hoplias aff. malabaricus is abundant in the Mogi-Guaçu River. The aim of this study was to perform an inventory of the species of metazoan that parasite this species of fish taken from oxbow lakes of the Mogi-Guaçu River. The Mann-Whitney test was used to statistically analyze the possible influence of the sex of the host on the group with the highest parasite richness and the greatest abundance of parasites. Simpson’s diversity index was used to determine parasite diversity among the zoological groups of parasites of H. aff. malabaricus with the highest index. A total of 78 specimens of H. aff. malabaricus were examined. Among the zoological groups of metazoans found, the phylum Nematoda had the greatest number of species. Among these, the larval stage of Contracaecum sp. was most abundant. The sex of the host had a significant effect, with parasites more abundant in female fish (Z(U)=0.043; p<0.05). The digenean Parspina argentinensis, the nematodes Procamallanus (S.) iheringi, Rhabdochona acuminata and Hysterothylacium sp. and copepods Vaigamus sp. and Lernaea cyprinacea have not previously been recorded as parasites of H. aff. malabaricus.