Toxicity and effects of copper sulfate on parasitic control and hematological response of tambaqui Colossoma macropomum

Abstract

The purpose of this work was to determine the mean lethal concentration (LC_50-96h) of copper sulfate (CuSO₄) for juveniles Colossoma macropomum (Characidae), to evaluate the effectiveness of different concentrations of CuSO₄ on elimination of parasites, as well as to study the effects of CuSO₄ on blood parameters after short-term exposure. After determination of the LC_50-96h from 17.5 mg L^-1 of CuSO₄, it was investigated the effects of exposure for 48 h to 1.75, 4.37 and 8.75 mg L^-1 of CuSO₄ on parasites and blood parameters. In gills and skin, concentrations of 4.37 and 8.75 mg L^-1 of CuSO₄ eliminated Monogenoidea Anacanthorus spathulatus. In fish exposed to different concentrations of CuSO₄, plasma total protein, chloride, potassium, glucose and copper levels, hemoglobin and hematocrit were similar to controls, whereas sodium levels presented decrease in fish exposed to 1.75 and 4.37 mg L^-1. Red blood cell counts decreased in fish exposed to different three concentrations of CuSO₄, while the Mean Corpuscular Volume (MCV) increased. However, exposure to 8.75 mg L^-1 of CuSO₄ caused decrease on total leukocytes, lymphocytes, neutrophils and PAS-positive granular leukocytes (PAS-GL) number when compared to control fish.