goldfish, freshwater fish, genus Carassius, of the family Cyprinidae, popular in aquariums and ponds. Native to China, it was first domesticated centuries ago from the wild form, an olive-colored carplike fish up to 16 in. (40 cm) long. It reverts to this type when it escapes from domestication and has been known to hybridize with the carp. Breeders have developed bizarre varieties with fan, fringe, or veil tails and sometimes with double or triple fins. Some have bulging "telescope" eyes. The majority of those bred commercially are known as scaled goldfish and have a metallic sheen of red, gold, white, silver, or black. The rarer forms, which are called scaleless, actually have transparent scales and appear in bright red, blue, shades of purple, and calico patterns. Marketed goldfish range in length from 1 to 4 in. (2.5-10 cm). In pools, they are beneficial as well as ornamental, since they feed on mosquito larvae; however, their carplike feeding habits make them a nuisance in lakes and streams. Goldfish are classified in the phylum Chordata, subphylum Vertebrata, class Osteichthyes, order Cypriniformes, family Cyprinidae.

Ornamental aquarium and pond fish (Carassius auratus) of the carp family, native to East Asia but introduced into many other areas. The goldfish was domesticated by the Chinese at least as early as the Song dynasty (960–1279). It is naturally greenish brown or gray, but its colour varies. Selective breeding has produced more than 125 breeds, including the veiltail, with a three-lobed, flowing tail, and the common, pet-shop comet. They feed on plants and small animals and, in captivity, on small crustaceans and other foods. They have become naturalized in many parts of the eastern U.S.

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Calico or nacreous goldfish are goldfish of any breed that sport a mixture of metallic and transparent scales that produces a pearly appearance. The name "calico goldfish" is often associated, and sometimes confused, with the shubunkin goldfish.

Description

Calico goldfish have patches of red, yellow, grey and black along with dark speckles on a blue background. This nacreous coloration of usually extends over the fins.

Variants

Although calico coloration occasionally occurs in other fancy goldfish varieties such as telescope eyes, fantails, ryukins, orandas, and ranchus, this nacreous characteristic is exclusive to the shubunkins which are single-tailed fish that are similar to the common goldfish and could grow up to 12 inches in length.

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