Condition factor, hepatosomatic and splenosomatic relation of freshwater fishes naturally parasitized

Abstract

The present paper describes the mean values of the splenosomatic (SSR) and hepatosomatic relation (HSR) and alometric condition factor (Ka) in the Nile tilapia (Oreochromis niloticus Trewavas, 1983), pacu (Piaractus mesopotamicus Holmberg, 1887), piauçu (Leporinus macrocephalus Garavello & Britski, 1988) and in the tambacu hybrid (P. mesopotamicus male x Colossoma macropomum Cuvier, 1818 female) naturally infected with parasites. Specimens of O. niloticus were parasitized with Trichodina sp.; L. macrocephalus with monogenean helminths; P. mesopotamicus with Anacanthorus penilabiatus (Monogenea) and Piscinoodinium pillulare (Dinoflagellida); tambacu hybrid with monogenean, Lernaea cyprinacea and P. pillulare. Results suggested that the parasitism was responsible for the reduction in the condition factor of O. niloticus, L. macrocephalus and P. mesopotamicus, and the SSR of parasitized P. mesopotamicus. Nevertheless, parasitism did not change (P > 0.05) the HSR of parasitized O. niloticus, L. macrocephalus, tambacu and P. mesopotamicus