EFFECTS OF SURFACING PREVENTION AND UNILATERAL REMOVAL OF AIR-BREATHING ORGANS ON OPERCULAR FREQUENCY IN AN INDIAN AIR-BREATHING CATFISH, CLARIAS-BATRACHUS (LINN.)

Opercular frequency was recorded by visual observations under surfacin g allowed and prevented conditions of normal and experimental Clarias batrachus without arborescent organs on its left side. A statistically significant elevation (P<0.01) in the rate of opercular frequency was recorded in fishes without access to air in intact and operated fish. The opercular frequency under prevented condition was higher (P<0.05) in the latter in comparison to the former one. However, interestingly unilateral removal of arborescent organs (AO) did not alter the inten sity of opercular activity under surfacing-allowed condition. Thus, it appears that: fish when prevented from surfacing compensates oxygen d ebt by increasing the rate of water flow over the gills through the en hancement of buccal pressure and activity of opercular suction pump.