The asp (Aspius aspius) is a European freshwater fish of the Cyprinid family. It is protected by the Bern Convention of endangered species and habitats (Appendix III). Asps are also on the IUCN Red List of endangered species.
Normally, asps are between 10 and 80 cm in length, with some reaching 120 cm, and weighing up to 12 kg. They inhabit lakes and lower reaches of rivers and estuaries. In spring, in April–June, asps migrate 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, the Czech Republic, Poland, Romania, Russia, Switzerland, Slovenia, the Netherlands, and Belgium. In Switzerland, asps have migrated 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 and other types of fishing.
Another species of asp (Aspius vorax) is found in abundance in the lakes and canals in what is now known as Camp Victory Base Complex near Baghdad International Airport. The asp is not believed to be native to this region, but was imported to improve sport fishing opportunities for the prewar ruling political party.
The only species of Aspius in Europe which can be diagnosed from other species of Cyprinidae in Europe by the following characters: anal fin with 12-14½ branched rays; scales on lateral line 64-76; maxilla extending beyond front margin of eye; and sharp keel between pelvic-fin and anal-fin origins covered by scales (Ref. 59043). Long shape body, laterally compressed with a long sharp head. Green back with silver to blue tints. Lighter flanks. Silver white belly. Pectoral, pelvic and anal fins grey to brown. Scale formula: 11-14/64-76/5-6 (Ref. 40476).
Habitat: Open water of large and mid-sized lowland rivers and large lakes. Spawns on gravel or submerged vegetation in fast-flowing water. Lake populations migrate to tributaries.
Biology: Lives more than 10 years. Spawns for the first time at 3-5 years. Reproductive success seems to be associated with low water level and high spring temperatures. Spawns more than one season, in March-early April (mid-May in Volga), when temperatures rise above 8C (Rhine) or even less (4-6C in Terek), at places with strong current. Spawning lasts about two weeks. Eggs adhere to gravel or submerged plants. Semi-anadromous individuals or populations (Terek) forage predominantly in estuaries and freshened parts of the sea, migrating to rivers only for spawning. Starts spawning migration in second half of October (Terek) and overwinters in lower part of river. Juveniles are gregarious predators; adults hunt in small groups or are solitary. Juveniles and adults feed predominantly on fish, especially on Alburnus alburnus or Osmerus eperlanus. Juveniles grow rapidly, reaching about 80-100 mm SL during first year. Regularly hybridizes with L. idus.