Acute Toxicity and Behavioral Responses of Common Carp Cyprinus carpio (Linn.) To an Organophosphate (Dimethoate)

Dimethoate, a broad spectrum OP insecticide is a potential toxic pollutant, adversely affecting the fauna of aquatic ecosystem. The aim of present study was to assess the acute toxicity of dimethoate on fingerlings of common carp, Cyprinus carpio. The fingerlings were exposed to dimethoate to determine LC values for 24, 48, 72 and 96 h and to study the behavioural alterations. The mortality data obtained was 50 analyzed by LC software program of U.S. EPA based on Finney's Probit Analysis statistical method and was 50 found to be 1.84, 1.78, 1.68 and 1.61 mg/L respectively. The test fish exhibited erratic swimming, increased surfacing, decreased rate of opercular movement, copious mucous secretion, reduced agility and inability to maintain normal posture and balance with increasing exposure time. Dissolved oxygen content of the troughs was measured at 24, 48, 72 and 96 h to assess the impact of toxicant exposure on oxygen consumption. Oxygen consumption of exposed fishes showed significant decline at all concentrations. It is concluded that dimethoate is highly toxic to fingerlings of common carp and severely affects their physiology and behaviour.