Effect of reproductive status, magnetic field exposure and photoperiod on temporal organization in air-gulping activity in Clarias batrachus

Abstract

The present study examined effects of pulsed magnetic field exposure (daily one hour magnetic field exposure at two times, 08:00–09:00 h and 16:00–17:00 h, 4000 Gauss) and continuous magnetic field exposure (4000 Gauss) for 30 days under LD (12:12), LL, and DD on temporal organization in air gulping activity in Indian freshwater catfish, Clarias batrachus, during different phases of its annual reproductive cycle. The air-gulping activity was monitored manually for about 15 minutes at four time-points (08:00 h, 12:00 h, 14:00 h, and 16:00 h) in each group. Time of day, photoperiod and magnetic field exposure all produced statistically significant effects on air-gulping activity during different phases of the annual reproductive cycle, excluding the spawning phase. The changes due to magnetic field exposure did not depend upon photoperiod. During most of the phases of the reproductive cycle, an increase or decrease in air-gulping activity was observed under DD and LL, respectively. It is concluded that air-gulping activity in C. batrachus exhibits daily variation, and that magnetic field exposure and photoperiod both produce modulatory effects on such activity.

Keywords:

• Magnetic field
• air-gulping activity
• photoperiod
• Indian catfish

Acknowledgement

Authors are thankful to Chhattisgarh council of Science and Technology, Raipur for financial support.