| Cyphocharax gilbert shows parasitic castration when infested by the crustacean Riggia paranensis, being unable to reproduce. Fish were sampled in the middle rio Itabapoana, Brazil, to study the prevalence of parasitism, growth, and sex steroid concentrations, considering the body size, sex, and reproductive condition of specimens. Most of the fish analyzed were infested (56.0%). The presence of two lines on the scales was more frequent among infested fish (22.0%) than among fish without parasites (12.0% for females and 10.0% for males). The occurrence of three lines on the scales was rare (3.5% among infested and 2.0% among females without parasites). These results suggest that growth of the host is faster than that of non infested fish. The serum... |
