Changes in bimodal oxygen uptake of an obligate air breather Anabas testudineus (Bloch) exposed to lindane

Bimodal [aquatic (V O 2 ) and aerial (V O 2 )] oxygen consumption of the air-breathing fish, Anabas testudineus (Bloch) exposed to 0.075 and 0.59 mg 1 −1 lindane was measured for 120 and 6 h respectively. In the controls 67.9% of O 2 was obtained from air (V O 2 ) whereas only 32.1% was obtained from water (v O 2 ) indicating that A. testudineus predominantly relies on aerial gas exchange. The fish held in both the concentrations of lindane showed a consistent increase in v O 2 , V O 2 and ( v + V) O 2 (total O 2 consumption) in most of the periods of exposure; but the increases observed in mean O 2 consumption at higher concentration were relatively lower than those in lower concentration. In 0.075 mg 1 −1 lindane, the stimulation seen in aerial respiration was more than that in aquatic respiration up to 24 h. The oxygen consumption returned to normal at 96 h in the lower concentration of lindane.