Histological and hematological evaluation of potassium permanganate exposure in channel catfish

Abstract

A histological and hematological study was performed to evaluate the effect of waterborne exposures of channel catfish Ictalurus punctatus to potassium permanganate (KMnO4). Three concentrations of KMnO4 were chosen to represent one, three, and five times the therapeutic concentrations (0.438, 1.315, and 2.190 mg/L, respectively), based on the KMnO4 demand, for 36 h, which is three times the usual treatment duration. The organs examined were the gill, liver, and trunk kidney. Differential leukocyte counts of neutrophils and monocytes in the blood and plasma enzyme analyses (lactate dehydrogenase and alanine transaminase) were also performed. The gill was the only organ to show microscopic lesions. Fish exposed to the therapeutic concentration of KMnO4 for 36 h had mild hypertrophy and spongiosis in the gills sampled during exposure, but no lesions were noticed 2 d postexposure. Gills of fish exposed to three and five times the therapeutic dose had extensive hyperplasia, epithelial hypertrophy and necrosis, lamellar fusion, spongiosis, leukocytic infiltration, obliteration of the interlamellar space with an inflammatory exudate containing necrotic epithelial cells, and occasional multifocal hemorrhages. No mortalities were observed in fish not exposed (control) or in fish exposed to the therapeutic dose of KMnO4. Mortalities were only observed in fish exposed to three and five times the therapeutic dose of KMnO4 (9.4% and 49.6%, respectively) with most of these mortalities occurring from exposure to 2 d postexposure. The gills of surviving fish exposed to three and five times the therapeutic dose for 36 h appeared normal at 8 d postexposure. Neutrophil count and plasma alanine transaminase activity increased significantly in fish exposed to five times the therapeutic dose; lactate dehydrogenase activity showed no change. Exposure to the therapeutic dose at three times the therapeutic exposure time caused mild lesions but recovery occurred within 48 h postexposure. © by the American Fisheries Society 2002.