Abstract: Seven years monitoring of the operation of a step-pool fish-pass channel was conducted at the hydropower plant on the River Neisse, Poland. Initial observations, after fishway construction showed that the fish can’t pass it. The reason was the high water velocity and the highly turbulent nature of water flow. Also the attraction flow was to slow. Accordingly, measures to improve fish-pass efficiency were undertaken. Initially the water velocity was reduced by throttling of inflow by one third. After this a few fish were found in the trap placed at the exit of the fishway. As a next step the thalweg in the lower part of fishway channel was raised by stone layer and 3 additional steps were constructed. Also other parts of the channel bottom were elevated with stones, to reduce slope at some steps. Additionally the openings on each fishway chute were narrowed, in order to further reduce water velocity and to create a sinuous pattern of water flow. These changes lead to a significant reduction of average water velocity. The observations after these modifications showed significant increase of fish-pass efficiency reaching 1.5 fish per hour. Last modification applied was to narrow the attraction flow stream with stones. This resulted in substantial increase of fishpass efficiency – up to 5.8 fish per hour.