Acute Toxicity and Histopathological of Reward® Herbicide on Gill and Liver of Pacu (Piaractus mesopotamicus)

Abstract

The lethal concentration of 50% (LC(I)₅₀;96h) and the hystopathological effects of the herbicide Reward® on the pacu fish (Piaractus mesopotamicus) were evaluated under three laboratory assays. The fishes were submitted to 0; 0.27; 0.31; 0.39; 0.43; and 0.48 ml of Reward® L^–1 and gills and livers histologies were evaluated on the surviving fishes. The Reward® CL(I)₅₀;96h estimated was of 0.34 mL L^–1. In the treatments control and the 0.27 mL L^–1 no histopathological alterations in the gills and livers of the exposed fishes were found. On the gills, the 0.31 and 0.35 mL L^–1 treatment caused subepithelial edema in the secondary lamellas coating cells. In the 0.39 mL L^–1 and 0.43 mL L^–1 treatments, hyperplasia of the coating cells and apical fusion of the secondary lamellae were observed. On the liver, the 0.31, 0.35 and 0.39 mL L^–1 treatment caused diarrhea, hypertrophia and the presence of glycogen granules inside the hepatocytes, respectively. In the 0.43 mL L^–1 treatment hepatocytes necrosis was registered. The Reward® herbicide was not very toxic on the pacu and the most severe histopathological alterations like fusion of secondary lamellas on gills and necrosis of hepatocytes were noticed only on higher evaluated concentrations.