Goldfish - biology.

Goldfish - biology. Goldfish, species 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). 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. 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. Goldfish have been bred for many centuries in China. 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. 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. Scientific classification: The goldfish belongs to the family Cyprinidae. It is classified as Carassius auratus. Contributed By: Kenneth A. Chambers Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.