Abstract
The floods sometimes occur so that the discharge, velocity, flow depth are changed. In such situations, fish behaviors may be changed. However, there is little information on the fish behaviors in flood. In this study, the swimming behaviors of Zacco Platypus (Oikawa) in the increasing discharge flows were recorded with a digital video camera. It was found that swimming speed of Zacco Platypus increased with an increase of velocity. In contrast, the ground speed of Zacco Platypus did not so change, irrespective of increasing discharge. The ground speed and swimming distance of Zacco Platypus did not change, even if the acceleration of velocity is changed. The effects of the acceleration on the swimming behavior of Zacco Platypus was smaller than that of the velocity.
