These features include being found predominantly in fresh water and possessing Weberian ossicles, an anatomical structure derived from the first five anterior-most vertebrae, and their corresponding ribs and neural crests.

The function is poorly understood, but this structure is presumed to take part in the transmission of vibrations from the swim bladder to the labyrinth and in the perception of sound, which would explain why the Ostariophysi have such a great capacity for hearing.

Several species such as the various goldfish (Carassius auratus) breeds and the domesticated common carp variety known as koi (Cyprinus rubrofuscus var.

[7] At least some species of carp are able to survive for months with practically no oxygen (for example under ice or in stagnant, scummy water) by metabolizing glycogen to form lactic acid which is then converted into ethanol and carbon dioxide.

[8][9][10] In 1653 Izaak Walton wrote in The Compleat Angler, "The Carp is the queen of rivers; a stately, a good, and a very subtle fish; that was not at first bred, nor hath been long in England, but is now naturalised."

Demand has declined, partly due to the appearance of more desirable table fish such as trout and salmon through intensive farming, and environmental constraints.

[50] Selective breeding programs for the common carp include improvement in growth, shape, and resistance to disease.

[54] Schaperclaus (1962) showed resistance to the dropsy disease wherein selected lines suffered low mortality (11.5%) compared to unselected (57%).

A popular lyric circulating as early as 2,000 years ago in the late Han period includes an anecdote which relates how a man far away from home sent back to his wife a pair of carp (Chinese: 鲤鱼; pinyin: Liyu), in which, when the wife opened the fish to cook, she found a silk strip that carried a love note of just two lines: "Eat well to keep fit, missing you and forget me not".

At the Yellow River at Henan (Chinese: 河南; pinyin: Hénán; Wade–Giles: Ho-nan) is a waterfall called the Dragon Gate.

This Dragon Gate was said to have been created after the flood by the god-emperor Yu, who split a mountain blocking the path of the Yellow River.

Other famous Dragon Gates are on the Wei River where it passes through the Lung Sheu Mountains and at Tsin in Shanxi Province.

The fish's jumping feature is set in such a proverbial idiom as "Liyu (Carp) jumps over the Dragon Gate (Chinese: 鲤跃龙门)," an idiom that conveys a vivid image symbolizing a sudden uplifting in one's social status, as when one ascends into the upper society or has found favor with the royal or a noble family, perhaps through marriage, but in particular through success in the imperial examination.

The modern Japanese Koi fish are a brightly colored species of the Amur carp that have been bred by rice farmers in Japan since the early 19th century.

[66] This subspecies of carp plays a significant role in Japanese art, often being depicted as symbols of luck, strength, and tenacity.

Their bright colors and unique patterns present a high degree of eloquence to the Japanese people, thus creating a level of respect and appreciation for the Koi.