The crucian carp is a widely distributed European species, its range spanning from England to Russia; it is found as far north as the Arctic Circle in the Scandinavian countries, and as far south as central France and the region of the Black Sea.

[7] They are broadly described as having a body of "golden-green shining color",[8] but a more precise source states that young fish are golden-bronze[9] but darken with maturity,[9] until they gain a dark green back, deep bronze upper flanks, and gold on the lower flanks and belly,[9] and reddish[citation needed] or orange[10] fins,[11] although other colour variations exist.

[citation needed] There are reports of hybridisation between the crucian and domestic or feral goldfish,[10] which has been verified by production of viable hybrids in laboratory conditions.

[14] In addition, crucian carp with the deep-bodied morphology exhibit reduced growth rates when compared to their sleeker-bodied counterparts.

During summer the fish also may survive anaerobic conditions by this metabolic expedient, though only to a far more limited extent; the winter phenotype can sustain fermentation as a substitute for respiration for several weeks on end.

The British rod-caught record for largest crucian is four pounds, nine ounces, (2.085 kg) landed by Martin Bowler in 2003, tied by Joshua Blavins in 2011.

Aside from confusion in nomenclature, there is the practical issue of distinguishing true crucian carp from goldfish hybrids in, e.g., competitive coarse fishing.

Crucian carp are considered a vital part of the pond ecosystem as they possess an ability to clean up the excrement of other organisms, thus preventing nitric overload.

2011) show total production C. crassius at 1,957,337 tonnes, worth US$2,135,857,000, ranked 9th in worldwide in aquaculture, including marine fish and crustaceans,[21] however these statistics treat the Asian C. gibelio carp as a subspecies of the European crucian carp,[22] and it is evident that the greater bulk of this number is from the Asian fish farmed in China.

In Poland, crucian carp (Polish: karaś) is considered the best-tasting pan fish, and traditionally served with sour cream (karasie w śmietanie).