Physicists are also interested in fish—above all when they are researching the formation of structures. A research team from Heinrich Heine University Düsseldorf (HHU) and the University of Bristol (United Kingdom) has examined the schooling behavior of zebra danio (Danio rerio, also known as "zebrafish") using methods from the field of multi-particle physics. They explain that groups of just three fish already move in a similar way to large schools while, by contrast, two fish display completely different behavior.