In the present work an attempt has been made to study the correlation, if any, between the cyclic changes in oxygen consumption (Vo?) and different haematological parameters in an air breathing fish, Anabas testudineus (Bloch). Two peaks of activity were marked in both the parameters. A positive correlation occurs between RBC/VOZ. Hb/Vo2 and PCV/Vo2 in both the sexes. The increase in VO2 seems to be more associated with the increase in RBC counts than with the increase in Hb content and PCV. Cyclic changes in Vo2 and different blood parameters show parallelism and a physiological balance exists between these two parameters.