Acute Toxicity Bioassay of a Pyrethroid Pesticide Bifenthrin to the Asian stinging Catfish, Heteropneustes Fossilis (Bloch)

Abstract

Bifenthrin is a type-I synthetic neopyrethroid pesticide having eight different stereoisomers. The current study aims to assess the short-term toxic effect of Bifenthrin to freshwater fish, Heteropneustes fossilis. The 24, 48, 72 and 96h LC50 values of bifenthrin to H. fossilis were 4.82, 4.47, 3.54 and 3.40 µg/l respectively. There was a significant variation (p<0.05) in the mortality of the treated fish exposed to bifenthrin with respect to the control at all the hours of exposure. A significant variation (p<0.05) between rate of mortality of H. fossilis and time slots (24-96h) was recorded for the final selected doses of bifenthrin except 4.0, 4.5 and 5.5 µg/l concentration of the toxicant. A vigorous mucous secretion and hyper-excitability was observed in the fish at the higher doses of bifenthrin specifically at 24h and 48h time slots. There was a profound loss in equilibrium of the treated fish particularly at the higher doses at 72h and 96h time slots. The gradual increase in dose of bifenthrin resulted in significant increase (p<0.05) in opercular movement of the fish with respect to the control. On the other hand, opercular movement showed a significant increase (p<0.05) with the advancement of time for all the treated doses. Therefore, bifenthrin is indicated to be very strongly toxic to fish.