The identification of parasite taxa was performed using specialized literature and consulting paratypes. Values of the relative condition factor were obtained for all individual as described by Le Cren (1951). With the logarithms of the values of standard length

(Ls) and total weight (Wt) of each individual host, the curve was adjusted for Wt/Ls (Wt = a·Ltb) and the values of the regression coefficients a and b were estimated. The values of a and b were used for estimating values theoretically predicted of body weight (We) by using the equation: We = a·Ltb. Then the relative condition factor (Kn) was calculated, which corresponds to the ratio between the observed weight and the theoretically expected weight for a given length (Kn = Wt/We). The non-parametric test Kruskal–Wallis (H) was used to test differences of the mean Kn between the environments in the floodplain of the Upper Paraná River, www.selleckchem.com/products/LBH-589.html considering that different biotopes can influence the Kn. To assess the relationship between infracommunities and infrapopulations of parasites with the relative condition factor, the nonparametric Spearman’s rank correlation coefficient (rs) was applied for the variables Kn of each parasitized fish × total number of species in the infracommunities, Kn of each parasitized fish × total number of individuals in the infracommunities and Kn of each fish × abundance of each parasite species. Analyses in

the infrapopulations were applied to species with prevalence higher than 10%, as suggested by Bush et al. (1990). The Mann–Whitney’s U-test with correction selleck screening library for ties – Z(U) – was used to test differences between the mean Kn of males and females and parasitized and non-parasitized fish for each species ( Zar, Ribonucleotide reductase 1996). The level of significance

adopted was p < 0.05. Fifty-eight taxa of metazoan ecto and endoparasites were identified. Leporinus lacustris harbored 31 species, Leporinus friderici 32, Leporinus obtusidens 28 and Leporinus elongatus 25 species. Taxa recorded in the four host species, sites of infection/infestation and parasitism indicators are presented in Table 1. The mean values of the host’s Kn for total sample are presented in Table 2, where the means for males and females are also shown. The Kn did not differ significantly between males and females (L. lacustris: Z(U) = 1.776, p = 0.075–L. friderici: Z(U) = 1.849, p = 0.064–L. obtusidens: Z(U) = 0.693, p = 0.486–L. elongatus: Z(U) = 0.477, p = 0.632). It also did not differ between hosts collected in three types of environments (L. lacustris: H = 0.359, p = 0.825–L. friderici: H = 1.410, p = 0.493–L. obtusidens: H = 1.162, p = 0.559–L. elongatus: H = 0.812, p = 0.661). Thus, all fish of each species were treated as one data set. Among the analyzed specimens of L. lacustris, 4 and 45 were unparasitized by ecto and endoparasites, respectively. For L. friderici these numbers were 4 and 27, for L. obtusidens 4 and 17, and for L. elongatus 2 and 9, respectively.