ABSTRACT
Acute toxicity of commercial grade organophosphate insecticide, quinalphos (25% emulsified concentration) to common carp (Cyprinus carpio) was tested through bioassay. The acute toxicity of quinalphos to the fingerlings exposed for 96 hr was found to be 2.75 ppm. For sub lethal toxicity study, the fish were exposed to two concentration viz., 1/10th of LC50 (0.275 ppm) and 1/5th of LC50 (0.55 ppm) along with lethal concentration (2.75 ppm) as reference for 48 hr. The carps were under stress and mortality was insignificant in both sub lethal and lethal concentrations. However, considerable variation in respiration rate and food consumption rate was observed in both lethal and sublethal concentrations. The alteration observed in the physiological condition may be a consequence of impaired oxidative metabolism and elevated physiological stress by fish against quinalphos.
