Ecology of parasites of Metynnis lippincottianus (Characiformes: Serrasalmidae) from the Eastern Amazon Region, Macapá, State of Amapá, Brazil.

The present study provides the first investigation on the ecological aspects of the parasites M. lippincottianus from the Amazonian basin, as well as the parasite-host relationship. 76 out of the examined fish (98.7%) were parasitized by at least one species of parasites. A total of 8,774 parasites were collected, being Ichthyophthirius multifiliis,Anacanthorus jegui,Dadayius pacupeva, Digenea gen. sp. (metacercariae), Procamallanus (Spirocamallanus)inopinatus, Procamallanus (Spirocamallanus) sp., Spinoxyuris oxydoras, Contracaecum sp. larvae, Dolops longicaudaand Hirudinea gen. sp. Ichthyophthirius multifiliiswas the dominant species, followed by A. jegui. Among the endoparasites, S. oxydoras andD. pacupevawere predominant. The mean diversity of parasites was HB = 0.96 ± 0.32 and there was aggregate distribution pattern. A positive correlation of body weight with the abundance of I. multifiliisand S. Oxydoraswas observed, whereas a negative correlation of body weight with abundance of the Contracaecum sp. larvae was found. The relative condition factor (Kn) was not negatively affected by parasites, and a positive correlation between Kn and abundance of I. multifiliis, S. oxydoras andD. pacupevawas found. This study is the first one to record I. multifiliis, D. longicauda and A. jeguiparasitizing M. lippincottianus, as well as the first record of D. pacupeva and S. oxydorasin the Amazonas river system