The aquatic research institute Eawag conducted, in collaboration with Energie Wasser Luzern (EWL), an evaluation of the fish ladder at the hydroelectric plant Mühleplatz in Lucerne. Thereby, video footage of fishes passing by an observation window was captured and manually evaluated, which was very labor intensive. We searched for a software approach to automatically analyze the video footage. The task was to detect the fishes’ species, its swimming direction and count the number of passes in front of the camera.