ACUTE TOXICITY AND HISTOPATHOLOGICAL LESIONS IN SILVER PACU (Piaractus brachypomus) EXPOSED TO A MIXTURE OF THE HERBICIDE ROUNDUP AND THE SURFACTANT COSMOFLUX 411F

Objective. To determine the 50% lethal concentration (LC50) and anatomopathological lesions associated with exposure to a mixture of Roundup® herbicide and Cosmoflux® 411 surfactant in juvenile silver Pacu (Piaractus brachypomus). Materials and methods. Fish of 44.5 ± 3.7 g body weight were exposed for 96 h to several concentrations of herbicide plus surfactant mixture. Mortality was recorded at 96 h and tissue samples were collected for histopathological evaluation. Results. The LC50 was 23.42 mg.l-1 for Roundup® (p<0.05) and 0.19 mg.l-1 for Cosmoflux® 411F (p<0.05) in the mixture. Necrotic and proliferative lesions were seen in the gills as well as hemorrhages and aneurysms in lamellae. In the liver, apoptotic and necrotic processes, lipidic vacuolization and cytoplasmic hyaline droplets in the hepatocytes were observed. In the telencephalon, apoptosis and necrosis of associated and non-associated neuronal bodies to eosinophilic granule cells/mast cells, and gliosis were found. In the intestine, vacuolization in the apical border of enterocytes, and leukocyte infiltration in the lamina propia were detected. In the skin, hyperplasia and hypertrophy of pavimentous and mucous cells as well as epidermal leukocyte infiltration and subepidermal pigment accumulation were found. In the caudal kidney, hemorrhages and mild multifocal necrotic lesions were observed. Conclusions. The Roundup® herbicide plus Cosmoflux® 411F surfactant mixture in the concentrations and the ratio used caused histopathological lesions in the gills, skin, brain, liver, anterior intestine and caudal kidney in exposed juvenile silver pacu.