The Chair for Hydraulic Engineering and the Chair for Geodetic Measuring Systems and Sensor Technology are developing a 3D fish tracking system, which records the coordinates of the fish’s trajectories in three dimensions. Various flow parameter can be assessed along the fish’s path using a 3D hydrodynamic numerical model as well as grid measurements. Thus, within the meaning of ethohydraulic analysis, a direct comparison of the swimming paths to hydraulic signatures can be made. In order to use the tracking system in the field, camera technologies shall be applied, that are even functional in high water turbidity or low light conditions.