Effect of some hormones and pharmacological drugs on oxygen uptake and equivalent energy utilization (E.E.U.) has been made in an air breathing fish, Mastacembelus armatus (Lac). The value for oxygen uptake (mol2h) and E.E. U. (K.cal/h) in control (45.0±1.5g) were 4.512 Mlo2/h and 0.0216 K.Cal/h respectively. Treatment of hydrocortisone, adrenaline, progesterone and thiouracil bring about significant decrease while the treatment of testosterone and L-thyroxin bring about significant increase in oxygen uptake and E.E. U.