Indian carp (Cirrhinus mrigala) exposed to two sub-lethal concentrations (0.815 mg/L and 1.63 mg/L) of diazinon for 30 days showed a significant decrease in erythrocyte count, hemoglobin concentration, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, plasma levels of total protein, albumin, globulin, activity of enzyme acetylcholinesterase and a significant increase in plasma glucose levels when compared with controlled fish (P<0.05). Compared to the controlled fish, leukocyte count decreased significantly in fish exposed to both sub-lethal concentrations and the plasma activities of enzyme asparate aminotransferase and alanine aminotransferase increased significantly after 20 and 30 days in fish exposed to 0.815 mg/L of diazinon, while the activities of these enzymes in fish exposed to 1.63 mg/L of diazinon increased significantly at all sampling periods (P<0.05). On the other hand, the plasma activity of the enzyme lactate dehydrogenase decreased significantly in both diazinon treated fish groups after 10 days of exposure (P<0.05) and returned to the normal value after 20 and 30 days of exposure. In conclusion, long-term exposure to diazinon at sub-lethal concentrations induces severe physiological alterations in C. mrigala that may potentially disrupt their survival in their natural habitat.
Diazinon; toxicity; hematology; biochemistry; Indian carp (Cirrhinus mrigala)