The name comes from Lower German karusse or karutze, possibly from medieval Latin coracinus (a type of river fish).

Crucian carp (Carassius carassius) is a freshwater fish of the crucian carp family. The common (golden) crucian carp inhabits water bodies of Central and Eastern Europe, lakes and rivers of Siberia (from the Ob to the Lena). It reaches a length of 45-50 cm and a weight of up to 3 kg. It has a tall, almost round body, small head, long dorsal fin. It is found mainly in shallow overgrown lakes, mudflats, peat pits with standing water and muddy soil, rarely in river beds and large lakes. Under unfavorable habitat conditions and low food supply, it forms a dwarf form characterized by a large head, slow growth and early maturation. It matures in 3-4 years. Spawning is portioned, eggs are deposited on vegetation in June-July, at a temperature of at least 14 ° C. The fecundity is up to 300 thousand eggs. Fecundity up to 300 thousand eggs. It feeds on zooplankton, larvae of aquatic insects and vegetation. Fishery object.

They are widely described as having a body of "golden green radiant color", but a more accurate source states that young fish are golden-bronze, but darken with age until they have a dark green back, dark bronze upper part of the sides and golden lower part of the sides and belly, and reddish or orange fins, although other color variations exist. One distinguishing characteristic is the convexly rounded fin, unlike goldfish hybrids (C. gibelio), which have concave fins.