Ethohydraulics is the transdiscipline linking behavioural science (ethology) and flow behaviour (hydraulics). Ethohydraulic studies provide repeatable and scalable insights into the reactive behaviour of aquatic animals. The findings can be used to derive limits and guidelines as well as design specifications for the planning of hydraulic engineering facilities. In this essential book, the authors provide an overview of the fundamentals and methodological approaches of ethohydraulic investigations. In addition to real-world case studies, current developments and future advances are provided. This Springer essential is a translation of the original German 1ststedition essentials,Ethohydraulik by Boris  Lehmann, published by Springer-Verlag GmbH Germany, part of Springer Nature in 2021. The translation was done with the help of artificial intelligence (machine translation by the service DeepL.com). A subsequent human revision was done primarily in terms of content, so that the book will read stylistically differently from a conventional translation. Springer Nature works continuously to further the development of tools for the production of books and on the related technologies to support the authors.