The RETERO project develops modern and scientific methods with the aim of significantly reducing and, in the long term, completely replacing fish experiments for assessing the risk of turbine passages. Primary ethohydraulic investigations of fish behavior of turbine inlet accelerated flows were done at the Hubert-Engels-Laboratory of the Technische Universität Dresden in cooperation with the Institute of Freshwater Ecology and Fisheries Biology Jena, to observe their reactions in a controlled environment. These findings provided the project's collaborative partners with a sound basis for developing