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Acute toxicity and histopathological of Reward ® herbicide on gill and liver of pacu (Piaractus mesopotamicus) The lethal concentration 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 in 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 subepitelial 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 secundary lamellae were observed. On the liver, the 0.31, 0.35 and 0.39 mL L ‐1 treatment caused diarreha, hypertrophia and 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. |
