抄録
Swimming behavior of isolate or a couple of fish in running water has not been investigated. Recently, Onitsuka et al. investigated on the swimming behavior of isolated ayu in running water. In this study, the swimming behavior of a couple of ayu in running water was investigated. It was found that the swimming speed in the streamwise direction increases with an increase of the flow velocity. In contrast, the swimming speed in the spanwise direction is constant, irrespective of the flow velocity. The turning angle of swimming trajectory decreases with an increase of the flow velocity. The swimming speed for each branch decreases in compared with that of isolate ayu.
