Acute Toxicity of Cypermethrin (A Pyrethroid Pesticide) to Post-Fingerlings of the African Mudfish Clarias gariepinus (Burch, 1822)

Abstract

Post-fingerlings of African mudfish, Clarias gariepinus (Burch, 1822), (mean weight 12.6+0.8g SEM, mean; total length, 10.4+1.1cm SEM) were exposed to different concentrations (0, 0.025, 0.05, 0.10 and 0.20 ppm) of cypermethrin in a static renewal bioassay to determine the 96hrLC50. Fish treated with cypermethrin showed abnormal behavior characterised by restlessness, uncoordinated movements, loss of equilibrium, gulping of air, period of quiescence and then death. The sub-lethal responses of the fish to the pesticide were more pronounced on opercular ventilation (y=64.45+115.6x) than on tail beat frequency (y=442+84.64x). The 96hrLC50 and safe concentration were 0.034 and 0.0034 respectively, indicating that the pesticide is highly toxic to this non-target fish.


[IJARD Vol.3 2002: 144-149]