. Parasites in gills of farmed Brycon amazonicus (Characidae, Bryconinae) in stream channels of Turumã-Mirim, Amazonas State, Brazil

Abstract

The purpose of the present study was to determine the prevalence and intensity of parasites in the gills as well as the condition factor of farmed Brycon amazonicus (Spix e Agassiz, 1829) from three stream channels in Tarumã-Mirim, Manaus, Amazonas State. Sanitary conditions of stream channels, fish handling, and water physiochemical parameters were monitored. From the 150 examined fish, 25.0% were contaminated by protozoan Ichthyophthirius multifiliis (18,0%) and by leeches Placobdella sp. (7.0%). The prevalence of I. multifiliis in the stream channels was of 22.0%, 18.0% and 14.0%, respectively, and the average intensity was high only in the stream channel that maintained fish in high population density. The leeches Placobdella sp. were found only in one stream channel. There was no seasonal variation in the infection by I. multifiliis; however Placobdella sp. infected the hosts only in January and March. Condition factor of parasitized fish was significantly lower (p < 0.001) than on unparasitized fish, but, it was not correlated with the parasites intensity.