In fisheries science, flowing water bodies in the temperate zones of Europe are traditionally divided into fish regions, each of which is characterised by a predominant fish species and a typical range of associated species. The riverine zone concept, on the other hand, can be applied to all climate zones and continents. It is based on abiotic factors and distinguishes brooks (rhithral rivers) from rivers (potamal rivers), dividing the two into three additional zones respectively (ILLIES, 1961). For central European water bodies, however, this nomenclature is synonymous with the classification according to fish regions.
Guideline Upstream Fishways on German Federal Waterways (AH FAA), Bundesanstalt für Wasserbau (BAW) und Bundesanstalt für Gewässerkunde (BfG), Version 2.0, 26/06/2015 (retrieved 10.05.2017); Illies, J. (1961), Versuch einer allgemeinen biozönotischen Gliederung der Fließgewässer. Int. Revue ges. Hydrobiol. Hydrogr., 46: 205–213. doi: 10.1002/iroh.19610460205