The effect of chronic toxicity after 10th days, 20th days and 30th days of three sub-lethal doses of nickel and chromium on bimodal oxygen consumption was determined using closed glass respirometer in Anabas testudineus. The mean aerial oxygen consumption increased from 82.8-88.27 and 83.02-94.65 ml O /kg/hr in nickel and chromium 2 treated fish. The aquatic and total oxygen consumption decreased from 77.49-45.58 and 160.29-135.05 ml O /kg/hr in 2 nickel intoxicated fish. On the other hand, in chromium treated fish, the decrease in aquatic and total oxygen consumption was respectively from 80.98-37.61 and 159.85-132.26 ml O /kg/hr. The work indicates that nickel toxicity has 2 less effect to this fish in comparison to chromium.