The asp (Aspius aspius) is a European freshwater fish of the Cyprinid family. Normally asps are between 10 and 80 centimeters in length, with some reaching 120 centimeters, and weighing up to 12 kg. It inhabits lakes and lower reaches of rivers and estuaries. In spring, in April–June, the asps migrates from lakes to streams for spawning. Spawning is triggered by the rise in temperature and usually starts at 6°C. The eggs attach to rocks, gravel and water plants. After around two weeks they hatch and the fry drift downstream to calmer waters.
Asps can be found in Estonia, Germany, Norway, Sweden, Finland, Poland, Romania, Russia, Switzerland, Slovenia, the Netherlands and Belgium. In Switzerland asps have immigrated through the Rhine-Main-Danube Canal, as in Croatia, Austria, Hungary and Slovakia. In the eastern regions of Europe it is a common species in flowing waters, and popular for fly other types of fishing.