Observations on parasite fauna of centropomus undecimalis and C. parallelus (perciformes) bred in southern Brazil, and its possible influence on the welfare of fishes.

Abstract

The metazoan parasite fauna of snooks, Centropomus parallelus and Centropomus undecimalis, cultured in southern Brazil and parasite?s influence on the relative condition factor (Kn), are investigated. Snooks were parasitized by two species of gill monogeneans belonging to Rhabdosynochus (Diplectanidae) genus and by one endoparasitic digenean species Acanthocollaritrema umbilicatum (Acanthocollaritrematidae). Centropomus parallelus and C. undecimalis showed similar prevalence rates of Rhabdosynochus spp., but greater mean intensity and abundance rates were found in C. parallelus. On the other hand, there was no significant difference on prevalence, mean intensity and abundance of A. umbilicatumfor both hosts. The mean abundance of Rhabdosynochusspp. decreased as the hosts´ length and weight increased. Since the most parasitized fish species, C. parallelus, had lower weight than expected (Kn<1.0), the fact suggested that gill monogeneans might alter fish welfare. Current analysis reports a new host and a new locality for A. umbilicatum