Effects of parasitism of Cimotoids (Isopoda, Cymothoidae) on the lambari Deuterodon iguape (Eigenmann, 1907), in the Rio Una Basin, SP Victória Walczak Neves, Ursulla Pereira Souza

Abstract

The present study aimed to compare morphological and biological aspects between Deuterodon iguape lambaris not parasitized and parasitized by the isopod belonging to the Cymothoidae family. The fish were collected in streams in the Rio Una watershed, São Sebastião, SP, with electric fishing gear, in 2017. In the laboratory, the individuals were separated into non-parasitized and parasitized through visual inspection. Thirty-two (32) subjects were selected for the study. The fish were measured, weighed and dissected. The sex ratio, degree of fullness and stage of maturation were compared using the chi-square test. The allometric condition factor between non-parasitized and parasitized fish was calculated from the weight-length relationship (Wt=a.CPᵇ). For comparisons of means, the Student's t test was used. The mean mouth height between non-parasitized (0.37 cm) and parasitized (0.46 cm) D. iguape showed a significant difference (p = 0.0094), as well as the mean allometric condition factor (K) between D. iguape non-parasitized (K=1.06) and parasitized (K=0.96) (p=0.049). In conclusion, the group parasitized by Cymothoidae isopods of D. iguape showed morphological modification in the oral region and a decrease in the condition factor, demonstrating lower body conditions of the parasitized specimens compared to the non-parasitized.