Acute toxicity impacts of hexavalent chromium on behavior and histopathology of gill, kidney and liver of the freshwater fish, Channa punctatus (Bloch).

Alteration in behavioral patterns and histopathology of gill, kidney and liver were studied in Channa punctatus, after acute exposure to hexavalent chromium. The 96h LC(50) of chromium salt, potassium dichromate was determined to be 41.75mg/L. The exposed fish displayed erratic swimming and became lethargic. The changes in gills were characterized by epithelial hyperplasia, lamellar fusion, oedema, epithelial lifting, epithelial necrosis and desquamation, aneurism as well as curling of secondary lamellae. Hypertrophy of epithelial cells of renal tubules with reduced lumens, atrophy of the renal tubules, glomeruli contraction in the Bowman's capsules and necrosis of haematopoietic tissues were observed in the trunk kidney of exposed fish. The interrenal cells of the head kidney exhibited distinct hypertrophy and vacuolization. The liver hepatocytes showed cytoplasmic vacuolization with the lateral nuclei arrangement. Hepatocytes atrophy and increase in sinusoidal space were also observed. The result showed that acute chromium toxicity severely affects the vital organs and normal behavior which may be deleterious for fish populations.