Mercury chloride toxicity in juveniles Prochilodus argenteus a species from southeastern Brazil

The aim of this study was to determine the 96-h LC₅₀ (lethal concentration for 50% of the test population in 96 h of observation) of mercury chloride (HgCl₂) and evaluated its absorption in the gills, liver, and muscle of juvenile "curimatã-pacu," Prochilodus argenteus. The fish were exposed for 4 days to different concentrations of HgCl₂: 0.000, 0.0375, 00.075, 0.150, 0.225, 0.300, and 0.400 mg L^-1 to get the 96-h LC₅₀, and the concentration of Hg in the tissues. The fish were exposed to different levels of HgCl2 (0.000, 0.0375, 00.075, 0.150, 0.225, and 0.300 mg L^-1), for 4 and 7 days, when different tissues (gills, liver, and muscle) were sampled. The mercury concentration values obtained were compared between tissues, days, and concentration of mercury in the water. The 96-h LC₅₀ for P. argenteus was 0.339 mg L^-1 of HgCl₂, within the range found for other neotropical and tropical species, showing a medium sensitivity. The concentration of Hg in the tissues increased from the muscle to the gills and liver, and according to the increasing concentration of HgCl₂ in the water. The fish liver is the most suitable tissue for environmental monitoring and for the evaluation of the consumed fished. Despite being the tissue that least accumulated mercury, the muscle must be evaluated because it is the part consumed by the population.