The goldfish (Carassius auratus) is a freshwater fish in the family Cyprinidae of the order Cypriniformes. It is commonly kept as a pet in indoor aquariums, and is one of the most popular aquarium fish. Goldfish released into the wild have become an invasive pest in parts of North America and Australia. Native to China, the goldfish is a relatively small member of the genus Carassius (which also includes the Prussian carp and the crucian carp). It was first selectively bred for color in imperial China more than 1,000 years ago, where several distinct breeds were developed. Goldfish breeds vary greatly in size, body shape, fin configuration, and coloration. Various combinations of white, yellow, orange, red, brown, and black are known.
History
Various species of carp (collectively known as Asian carp) have been bred and reared as food fish for thousands of years in East Asia. Some of these normally gray or silver species have a tendency to produce red, orange, or yellow color mutations; this was first recorded in Imperial China, during the Jin dynasty (266–420). During the Tang dynasty (AD 618–907), it was popular to raise carp in ornamental ponds and water gardens. A natural genetic mutation produced gold (actually yellowish orange) rather than silver coloration. People began to selectively breed the gold variety instead of the silver variety, keeping them in ponds or other bodies of water. On special occasions at which guests were expected, they would be moved to a much smaller container for display. By the Song dynasty (AD 960–1279), the selective domestic breeding of goldfish was firmly established. In 1162, the empress of the Song dynasty ordered the construction of a pond to collect the red and gold variety. By this time, people outside the imperial family were forbidden to keep goldfish of the gold (yellow) variety, yellow being the imperial color. During the Ming dynasty (1368–1644), goldfish also began to be raised indoors, which permitted selection for mutations that would not be able to survive in ponds. The first occurrence of fancy-tailed goldfish was recorded in the Ming dynasty. In 1603, goldfish were introduced to Japan. In 1611, goldfish were introduced to Portugal and from there to other parts of Europe. During the 1620s, goldfish were highly regarded in southern Europe because of their metallic scales, and symbolized good luck and fortune. It became a tradition for married men to give their wives a goldfish on their first anniversary, as a symbol for the prosperous years to come. This tradition quickly died, as goldfish became more available, losing their status. Goldfish were first introduced to North America around 1850 and quickly became popular in the United States. The largest breeder in the late 19th and early 20th century was Henry Bishop of Baltimore (1837-1907), known as the "Gold Fish King", his farms sold more than one million goldfish a year. It was believed to be the largest goldfish operation in the world.
Biology
Taxonomy
There has been considerable debate about the taxonomy of the goldfish. Previously, the goldfish was believed to be either a subspecies of the crucian carp (Carassius carassius), or of the Prussian carp (Carassius gibelio). However, modern genetic sequencing has suggested otherwise, and that modern goldfish are domesticated varieties of C. auratus that are native to Southern China. C. auratus are differentiated from other Carassius species by several characteristics. C. auratus have a more pointed snout, while the snout of C. carassius is well rounded. C. gibelio often has a grayish or greenish color, while crucian carp are always golden bronze. Juvenile crucian carp have a black spot on the base of the tail, which disappears with age. In C. auratus, this tail spot is never present. C. auratus have fewer than 31 scales along the lateral line, while crucian carp have 33 scales or more. Goldfish can hybridize with some other Carassius species of carp. Koi and common carp may also interbreed with goldfish to produce sterile hybrids.
Size Wild goldfish typically grow to between 4.7 inches (12 cm) and 8.7 inches (22 cm) but can reach 16 inches (41 cm). The size of pet goldfish depends upon its breed and the container it lives in; while it is a myth that goldfish grow to fit the size of their tank, its growth rate is influenced by the size of the tank. As of April 2008, the largest goldfish in the world was believed by the BBC to measure 19 inches (48 cm), in the Netherlands. At the time, a goldfish named "Goldie", kept as a pet in a tank in Folkestone, England, was measured as 15 inches (38 cm) and over 2 pounds (0.91 kg), and named as the second largest in the world behind the Netherlands fish. The secretary of the Federation of British Aquatic Societies (FBAS) stated of Goldie's size, "I would think there are probably a few bigger goldfish that people don't think of as record holders, perhaps in ornamental lakes". In July 2010, a goldfish measuring 16 inches (41 cm) and 5 pounds (2.3 kg) was caught in a pond in Poole, England, thought to have been abandoned there after outgrowing a tank. On November 16, 2020, a 15-inch (38 cm) goldfish weighing 9 pounds (4.1 kg) was found in a 16 acres (6.5 ha) lake in Greenville, South Carolina, while conducting a population survey of Oak Grove Lake.
Vision As a domestic fish, thus an easily accessible model organism, goldfish have one of the most studied senses of vision in fishes. Goldfish have four kinds of cone cells, which are respectively sensitive to different colors: red, green, blue and ultraviolet. The ability to distinguish between four different primary colors classifies them as tetrachromats.
Hearing Goldfish have one of the most studied senses of hearing in fish. They have two otoliths, permitting the detection of sound particle motion, and Weberian ossicles connecting the swim bladder to the otoliths, facilitating the detection of sound pressure.
Reproduction
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