Abstract
The number of fish that swim toward the fish-way entrance increase when priming water is added. The refbre, the priming water has a function to lead fish to the fish-way, and it is necessary in order for fi sh to run up smoothly. However, the circulation flow is sometimes formed downsteam. On such occasions, the run-up ratio decreases. By setting up a division wall between the priming water and main channel, the circulation flow is cancelled and the run-up and the leading ratio increase. The run-up ratio indicates the maximum value when priming velocity becomes 2.3 times overflow velocily. In that occasion, the overflow velocity indicates about seven times the number of a given fish's length.
