Recycling and utilization of metabolic wastes for energy production is an index of biochemical adaptation of fish under environmental pollution stress.

The activity levels of lactate dehydrogenase and lactic acid were assessed in various tissues of the fish during exposure to lethal concentration of group-II Pyrethroids (deltamethrin, cypermethrin, fenvalerate and fluvalinate) for a period of 72 hours. The results showed steady increased levels in all the tissues (blood, muscle, brain and liver) with response pattern characteristic of their own. The increased LDH activity and lactic acid levels indicate the shifting of aerobic glycolysis to anaerobiosis and its further utilization for energy production during adaptation to toxic stress.