Effect of parasitism on the relative condition factor of Astyanax bimaculatus (Characiformes: Characidae) a freshwater fish from Caatinga domain, Brazil

The present study aimed to evaluate the effect of parasitism on the condition factor of Astyanax bimaculatus (Linnaeus 1758) (Characiformes, Characidae), in Batateiras river, Salgado river basin, northeastern Brazil. A total of 242 host specimens were collected between August 2018 and February 2020. The host presented a community of metazoan parasites of 14 taxa, totaling 1,750 specimens collected, with mean total abundance of 7.23 specimens per fish, being the class Monogenea the most predominant taxonomic group. The relative condition factor (Kn) differed significantly between parasitized and non-parasitized individuals, in which the parasitized hosts presented higher values of Kn. The abundance of the monogeneans Characithecium costaricensis and Diaphorocleidus sp. showed positive and significant correlations with the Kn. Considering the sex of the host, males had higher parasite burden than females, although females present higher values of Kn. The parasitic burden of hosts did not show significant differences between seasonal periods.