"Women and cats will do as they please, and men and dogs should relax and get used to the idea."

- Robert A. Heinlein

The Goldfish

Goldfish

The Goldfish is a specie of soft-finned, freshwater fish of the minnow family. Goldfish usually measure about 8 to 15 cm (about 3 to 6 in) in length, although some have attained a size exceeding 30 cm (12 in). The goldfish resembles the carp (Cyprinus carpio) but differs from its relative in having no mouth barbels. Goldfish are exceptionally long-lived and have been reported to reach an age of 70 years. Goldfish are native to eastern Asia, but they have been successfully introduced into fresh waters throughout the world. In their natural state, goldfish are olive green in color and subsist on weeds and small invertebrates.

It was domesticated by the Chinese at least as early as the Sung dynasty (960-1279). Japanese culturists learned the art from the Chinese and carried their interest in the species to the point of holding annual goldfish exhibits throughout the country. Goldfish are reported to have been introduced into England in 1691 and into France in the middle of the 18th century, when specimens were received as gifts by the marquise de Pompadour, mistress of King Louis XV. Today they are produced in many countries on a sizable commercial scale. One goldfish hatchery, near Frederick, Maryland, occupies 40 hectares (100 acres) and has an annual production of 5 million fish.

The numerous varieties of domestic goldfish have all come from the wild goldfish of eastern Asia. Domestic goldfish have been bred for centuries, especially in Japan and China, and have adapted to fresh waters around the world. Goldfish can be extremely long-lived and have become popular as domestic pets. The goldfish is naturally greenish-brown or gray. The species, however, is variable, and numerous abnormalities occur. A deviant fish may be black, spotted, golden, white, or white with silver; it may have a trilobed tail fin or protruding eyes; or it may lack the normally long dorsal fin. Centuries of selecting out and breeding such abnormal specimens have produced over 125 breeds of goldfish, including the common, pet-shop comet; the veiltail, with a three-lobed, flowing tail; the lionhead, with a swollen "hood" on the head; and the celestial, with protruding, upward-directed eyes.

The occasional differences in color and form that they exhibit have been perpetuated and accentuated among domestic varieties by careful breeding. Upon escaping to a less protected environment, such as a river, selection for unusual color or form is not maintained and the species usually reverts to its natural, olive-green color.

The best-known domestic varieties of goldfish are golden red. Blind, albino forms have been produced by the Chinese, and varieties of these, completely white, or white with red fins, or silvery, compose the important fancy breeds of silverfishes. The telescope fishes are another important breed, developed by the Japanese, that are characterized by short, round bodies, broad heads with protruding eyes, and large bilobed or trilobed tails. In common varieties of this breed the eyes are turned outward, but in the celestial telescopes they are directed upward. The veiltails, or fringetails, are a fancy breed marked by long, veil-like fins; the calicoes are spotted goldfishes of any breed; and the fantails are goldfishes with two tails and two top fins.

The goldfish is omnivorous, feeding on plants and small animals. In captivity it does well on small crustaceans, and the diet may be supplemented with chopped mosquito larvae, cereal, and other foods.

Spawning occurs in spring or summer. As the season approaches, colours become brighter, the belly of the female enlarges, and the male may develop pinhead-sized tubercles on the gill covers, back, and pectoral fins. The eggs stick to water plants until hatching about a week later. Pet goldfish have been known to live 25 years; the average life span, however, is much shorter.

Goldfish thrive in large tanks or outdoor pools supplied with clean, well-aerated water kept at a temperature of 18° C (65° F). Their optimum diet is a mix of weeds, worms, small shellfish, and insects. Under such conditions they breed several times a year.

Chambers, Kenneth A. "Goldfish." Microsoft® Student 2007 [DVD]. Redmond, WA: Microsoft Corporation, 2006.