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Carassius auratus

By Robin Street

Geographic Range

Although goldfishes originated in China, they have now spread worldwide in aquariums, ornamental pools, and into the wild.

Habitat

In the wild, goldfish can be found in slow-moving, freshwater bodies of water. As with their close relative the carp, they thrive in slightely sludgy water. In an aquarium, bi-weekly water changes are a good idea as a goldfish tank is hard to keep clean. They thrive in a pond environment thus the addition of real plants is optimal if the owner is prepared to replace them fairly regularly; goldfish enjoy eating live plants. An aquarium with a dirt bottom is ideal but difficult to maintain. Small pebbles are a suitable substitute for the pond-like bottom. Typically, goldfish will survive in water temperatures ranging from freezing to 30 degrees centegrade. Fancy varieties(orandas, lionheads, ranchu, veiltailes...) should be kept in water no cooler than room temperature.

Goldfish prefer a pH range of 6.5-8.5.

  • Aquatic Biomes
  • lakes and ponds
  • rivers and streams

Physical Description

As there are over a hundred varieties of goldfish, coloration and physical characteristics vary greatly. The common goldfish has two sets of paired fins - the pectoral fins and pelvic fins, and three single fins- the dorsal, caudal, and anal fin. They lack barbels on the upper jaw, and lack scales on the head. Goldfish have exceptionally large eyes and acute senses of smell and hearing. They have 27-31 scales along their lateral lines. Goldfish have (rather than true teeth ) pharyngeal teeth in their throats which they use to crush food.

Goldfish can grow to be 3 kg and 45 cm long but are usually much smaller than this.

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    3.0 (high) kg
    6.61 (high) lb
  • Range length
    41.0 (high) cm
    16.14 (high) in

Lifespan/Longevity

Although there is one report of a pet goldfish who lived 43 years, 25 years is a more reasonable maximum lifespan for a goldfish kept in a pond. In an aquarium, ten years is more likely. In the wild, lifespan is undoubtedly less.

Behavior

In the wild goldfish will school to a certain extent. In aquariums or bowls, however, they can be kept separately. Goldfish are not particularly aggresive, thus combining sizes is not often a problem. It is worth suggesting that varieties which are drastically different should not be combined in a tank: e.g. a slow, heavy-bodied, veil-tailed Oranda with a fast, slightly more aggressive variety such as a comet.

Communication and Perception

Food Habits

In the wild, goldfish are omnivores. They eat plants, insects such as mosquito larvae, small crustaceans, zooplankton, and detritus.

In captivity, goldfish are commonly fed dried flake or pellet food. As pets, they should also be fed foods they would consume if they were in the wild. Good diet supplements include freeze dried Tubifex worms, mosquito larva, bloodworms, Daphnia, brineshrimp, and vegetation such as boiled peas and lettuce.

Predation

Just about anything that eats fish would eat goldfish.

Economic Importance for Humans: Positive

Goldfish farming has become an industry of notable size. Millions of fish are bred each year and sold to aquarium shops for resale to fish enthusiasts. In North America there is a demand for goldfish to be used as bait by anglers. Pet shops often have feeder goldfish to sell to owners of carnivorous aquarium fish.

Economic Importance for Humans: Negative

Introduced populations are due primarily to people releasing their pets into local waterways. Goldfish should not be released into ponds in the wild because they breed quickly and are capable of crowding out native fish species. They are considered pests in most places where they have been introduced.

Conservation Status

Goldfish are not in the least bit endangered.

Other Comments

Goldfish and common carp can hybridize.

Contributors

Robin Street (author), University of Michigan-Ann Arbor.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

Ethiopian

living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.

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Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

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bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

freshwater

mainly lives in water that is not salty.

herbivore

An animal that eats mainly plants or parts of plants.

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

World Map

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

References

A Fishkeeper's Guide to Fancy Goldfishes; Dr. Chris Andrews; Tetra Press; 1987.

The Audubon Society Field Guide to North American Fishes, Whales and Dolphins; 1993.

Froese, R., D. Pauly, eds.. 2002. "Species summary: Carrasius auratus" (On-line). Accessed 3 April 2002 at http://www.fishbase.org.

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