Science Fair Project Encyclopedia
For the Pepperidge Farm brand of snack crackers marketed in North America, see Goldfish (snack).
The goldfish (Carassius auratus auratus) is one of the earliest fish to be domesticated and is still one of the most commonly-kept aquarium fish. A relatively small member of the carp family (like the koi), the goldfish is a domisticated version of a dark-gray carp native to East Asia (first domesticated in China) that was introduced to Europe in the late 17th century. It will grow to a maximum length of 23 inches (59.0 centimeters) and a maximum weight of 6.6 lb (3.0 kg).
Goldfish natively live in rivers, lakes, and other slow or still moving bodies of water in depths up to 65.6 ft (20 m). They natively live in a subtropical climate and prefer freshwater with a 6.0 - 8.0 pH, a water hardness of 5.0 - 19.0 dGH, and a temperature range of 32 to 106 °F (0 to 41 °C). Their diet consists of crustaceans, insects, and plant matter. They lay their eggs on aquatic vegetation.
Part of its popularity is due to the goldfish's hardiness. It is a cold-water fish , and can live in an unheated aquarium or in an outdoor water garden. In a pond, it will even survive brief periods of ice forming on the surface, so long as there is enough oxygen remaining in the water and the pond does not freeze solid. Although edible, the fish are rarely eaten.
Selective breeding has produced several colour variations, some of them far removed from the "golden" colour of the original. There are also different body shapes, fin and eye configurations. Such extreme versions of the goldfish do need to be kept in an aquarium — they are much less hardy than varieties closer to the "wild" original.
Although goldfish are traditionally displayed in small "goldfish bowls", a healthy and happy goldfish requires at least ten gallons of water in order to live a full life: each additional fish requires an extra five gallons (nearly 20 litres) of water. In fact, some estimates run as high as twenty to fifty gallons (75 to 200 litres) per fish, depending on size. While it is true that goldfish can survive in a fairly wide temperature range, the optimal range for indoor fish is 68 to 72 °F (20 to 22 °C). Pet goldfish will happily eat too much food if given, and can easily get a fatal intestinal blockage that will cause a painful death. Goldfish rarely breed indoors and will eat any of their young that they happen upon.
A fad among American college students for many years was swallowing goldfish as a stunt. The first recorded instance was in 1939 at Harvard University. The practice gradually fell out of popularity over the course of several decades.
In many countries, the operators of carnivals and fairs commonly give goldfish away in plastic bags as prizes for winning games. In the United Kingdom, the government proposed banning this practice as part of its Animal Welfare Bill, though early 2005 reports suggest that this idea has been dropped.
It is often said that goldfish have a memory of only a few seconds, but this is not entirely true. Goldfish have what could be called a selective memory, that is to say they have some kind of conscience of what has happened on previous occasions, but are not sure what it was. They can be trained to do simple tasks such as eat from a certain ring inside their bowl, This is because they instinctively know that something good is in that area, they are just not sure what. If a predatory animal (such as a heron) is around, they will hide away through instinct for quite a while, but they do not know what it is they are hiding from, they simply know it is worth avoiding.
A study has said goldfish know about time and have a memory of three months, but this may not be true.
There is an urban legend that a pregnant goldfish is called a "twit" or "twat", but this was debunked by The Straight Dope.
- Black Moor
- Bubble Eye
- Celestial Eye
- Telescope Eye
- The Goldfish Sanctuary - Site of a now defunct goldfish rescue organization.
- BBC News Online - Goldfish are no longer to be given as prizes
- BBC News Online - Ban on goldfish prizes 'dropped'
- The Straight Dope - Is a pregnant goldfish called a twit?
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