The Crucian Carp (Carassius carassius) is a member of the family Cyprinidae, which includes many other fish such as the common carp, or the smaller minnows. They inhabit lakes, ponds, and slow-moving rivers throughout Europe and Asia. The crucian is a medium-sized cyprinid, which rarely exceeds a weight of over 3.3 pounds (1.5 kg). They usually have a dark green back, golden sides, and reddish fins, although other colour variations exist.

They are often caught as a sport fish: the British rod-caught record for largest crucian is four pounds, nine ounces, caught by Martin Bowler in a lake in southern England in 2003. There have been various bids for a breakage of this record since, but they have been passed off as the specimens have not been said to have been "true" crucians, but hybrids between the carp and one of its relatives, such as the goldfish, which are not native to the British Isles. These hybrids often exhibit hybrid vigour or heterosis, being much more adept at finding food and evading predators than either of their parents, and thus pose somewhat of a threat to the native carp population, and to other native aquatic animals.

These carp are also occasionally kept as freshwater aquarium fish, as well as in water gardens, although they are not commonly available commercially, mainly because they are not in particularly high demand due to the presence of more colourful fish such as the koi or orfe.

Many sources will claim that crucian carp are the wild version of the goldfish. While they are certainly very closely related and can be regarded as the ancestors of goldfish they are not the same subspecies. Analysis has revealed key anatomical differences between them; further details are on the goldfish page.

References

• Fish Holds Breath for Months

Carp

Chit-á-hî | Сребриста каракуда | Karausche | Karasino | Paprastasis karosas | Kroeskarper | Karuss | Karaś | Navadni koreselj | Ruutana | Карась | Ruda (fisk) | караш | 鲫鱼