Abstract
In this study, the mainly purpose is to make clear the behavior of straying fish in the downstream of a weir. Therefore, we carried out the model experiment by using the open channel where a pool-and-weir-fishway had been set up.As a result, number of straying fish in the downstream of the weir is approximately 60(%) or more. Then, straying fish moved in two patterns. In the case of Q=6(l/s), fish move to the downstream of the fish-way, in the downstream of the weir. In the second case of Q=18(l/s), staying fish exerted the unique behavior against the flow in the downstream of weir, because of speed velocity in the downstream of the weir.
