OPERCULAR ACTIVITY AND TEMPORAL ORGANIZATION OF SURFACING BEHAVIOR ININDIAN CATFISHES, CLARIAS-BATRACHUS AND HETEROPNEUSTES-FOSSILIS

Opercular and surfacing activity were observed in the Indian catfish C larias batrachus and Heteropneustes fossilis. In the series A experime nts, the opercular activity was monitored under two experimental condi tions, viz., (1) surfacing allowed and (2) surfacing prevented. A stat istically significant elevation of the rate of opercular activity was observed when air breathing was prevented in both species. In addition , a significant prevention effect and a time of day dependence of that were noticed in both species. In the series B experiments, temporal p atterns of surfacing and air-gulping activities were examined under an artificial LD 12:12 schedule at 2-h intervals over a period of 48 h. The inter air-gulping interval in minutes between two consecutive bout s was also recorded four times each day in both species. A significant 24-h rhythm was found for the rate of surfacing activity and length o f the inter air-gulping interval in both species. However, the overall activity appears to be much higher in Heteropneustes fossilis as comp ared to Clarias batrachus.