The present paper deals with the effect of certain pesticides (namely Dithane M-45 and Metacid 50) on aquatic, aerial and total oxygen consumption besides equivalent energy utilization (E. E. U.) in a fresh water facultative air breathing siluroid fish, Clarias batrachus (Linn. ). The exposure of fishes to both the pesticides at different concentrations caused significant decrease in total oxygen uptake but on the otherhand significant increase in O, uptake through aerial route was noticed. The reason for such changes have been discussed in this paper.