Lethal and sub-Lethal Toxicity of Chlorphyrifos on Fish Rohu( Labeo Rohita Hamilton, 1822)

Abstract

Chlorpyrifos is an organophosphate insecticide which is commercially used to control insect pest. It is second largest selling organophosphate and found to be more toxic to fish. Present study was performed to determine the acute toxicity of Chlorpyrifos (LC50 ), their behavioural changes after exposure to pesticide and also haematological study of Rohu (Labeo rohita). Acute toxicity test was accompanied following the standard method (OECD 203 testing guidelines, 1992). In treated fish alterations in various behavioural patterns respiratory metabolism, opercular beat rate and blood parameters were examined for sub-lethal end-points following 1 h, 24 h, 48 h, 72 h, and 96 h exposure. The LC50 value of Chlorpyrifos was found to be 0.362 mg/L. Behavioural changes were also observed in control and exposed fish. Schooling behaviour was observed to be disrupted in first day after exposure to pesticide. High opercular beat rate (p < 0.01) at 24 h and (p < 0.001) from 48-96 h and oxygen consumption rate was recorded in pesticide-exposed groups in comparison to control. The pesticide stress caused a significant elevation in haemoglobin (p <0.01). Glucose and protein content was found to be increased (p > 0.05) in the pesticide group, compared to the control. Some general behavioural changes such as erratic movement, gulping, schooling, mucus secretion, equilibrium, aggregating behaviour, and paleness in the body were observed in pesticide-exposed fish. The current study revealed that CPF was found to be highly toxic pesticide. Hence, its discriminate use should be avoided as it can contribute to decline of Rohu in natural habitat.