Acute toxicity and effects of malathion exposure on behavior and hematological indices in Indian carp, Cirrhinus mrigala (Hamilton)

Malathion is one of the most commonly used pesticides in agriculture. This study was aimed to investigate the acute toxicity of malathion as an aquatic pollutant on the behavior and hematological indices in Indian carp (Cirrhinus mrigala). A static experiment was conducted and 1, 24, 48, 72 and 96 hrs LC₅₀ values of malathion for the test fish were estimated as 14.55 mg/L, 12.48 mg/L, 11.56 mg/L, 10.85 mg/L and 9.32 mg/L, respectively. During 96 hrs exposure to 9.32 mg/L of malathion, behavioral abnormalities such as hyperactivity, cough, convulsions, erratic swimming, loss of balance, rapid opercular movements, gill mucous secretion, surfacing and gulping of air were observed in the test fish. The hematological changes in exposed fish after 96 hrs exposure to malathion included a significant decrease in erythrocyte count, hemoglobin content, hematocrit, leukocyte count and a significant increase in neutrophils count as compared to the control fish. In conclusion, acute exposure to 9.32 mg/L of malathion provoked behavioral and hematological abnormalities in Indian carp which offers a valuable tool to monitor malathion induced toxicity in fish.