Abstract
We investigated the heartbeat of mudfishes laying under stationary magnetic field for several hours in comparison with that of the control. The results show that the heartbeat of influenced mudfishes decreased to about 4/5. The variation of heartbeat is independent from the strength of the magnetic field and the exposed time. As a result the time that the influence of the magnetic field on the heartbeat remains is proportioned to the strength of the magnetic field and the exposed time. Such influence dosn't appear for weak magnetic field or short exposed time.
