Metazoan endoparasites of Myloplus nigrolineatus (Characiformes: Serrasalmidae) from upper Amazon river basin, Brazil.

The success of Trematoda and Nematoda infection in fish involves a complexity of variables. The objective of this study was to report the parasitological descriptors (prevalence, mean abundance, and mean intensity) and community status of Myloplus nigrolineatus as well as to evaluate the relationship between abundance and richness of endoparasites with biometric parameters, sex, Kn the hosts, percentage cover native vegetation and water temperature. A total of 7,256 endoparasites were found: 861 digeneas and 6,395 specimens of nematodes were collected in the intestine from Myloplus nigrolineatus. One species of Digenea and five species of Nematoda were collected. The initial documentation of the prevalence (%) of endohelminth species in M. nigrolineatus revealed the following: Dadaytrema oxicephala (70%), Chabaudinema americanum (52%), Cucullanus pinnai pinnai (13%), Myleusnema bicornis (65%), Procamallanus (Spirocamallanus) inopinatus (9%) and Rondonia rondoni (35%). The mean intensity and mean abundance were 329.82 ± 416 and 315.48 ± 417, respectively. The trematode Dadaytrema oxycephala was considered a central and dominant species. The total abundance was explained by the variables total length, relative condition factor (Kn), percentage cover native vegetation and water temperature. Fish relative condition factor (Kn) and sex were not influenced by the parasite infection and did not impair the body condition of the hosts. The GLMM showed there is no relationship between abundance and richness of endoparasites with percentage cover native vegetation, while that every twenty centimeters more in the total length of the hosts, the abundance of endoparasites in the intestine increases, approximately, 2 specimens.