Goldfish

This article is about the ornamental fish. For the American snack cracker, see Goldfish (snack). For other uses, see Goldfish (disambiguation).

Goldfish
Conservation status
Domesticated
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Cypriniformes
Family:	Cyprinidae
Genus:	Carassius
Species:	C. auratus
Subspecies:	C. a. auratus
Trinomial name
Carassius auratus auratus (Linnaeus, 1758)

The goldfish (Carassius auratus auratus) was 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 (which also includes the koi carp and the crucian carp), the goldfish is a domesticated version of a dark-gray/olive/brown carp native to east Asia (first domesticated in China) that was introduced to Europe in the late 17th century. The mutation that gave rise to the goldfish is also known from other cyprinid species, such as common carp and tench.

Goldfish may grow to a maximum length of 23 inches (59 cm) and a maximum weight of 9.9 pounds (4.5 kg), although this is rare; most individual goldfish grow to under half this size. In optimal conditions, goldfish may live more than 20 years (the world record is 49 years); however, most household goldfish generally only live six to eight years.

History

A wild Prussian carp showing yellow coloration. Some of the first goldfish may have looked like this.

In ancient China, various species of carp (collectively known as Asian carps) had been domesticated and reared as food fish for thousands of years. Some of these normally gray or silver species have a tendency to produce red, orange or yellow color mutations; this was first recorded in the Jin Dynasty (265–420).

During the Tang Dynasty (618–907), it was popular to raise carp in ornamental ponds and watergardens. Due to a natural genetic mutation, some of these carp displayed gold (actually yellowish orange) rather than silver coloration. People began to breed the gold variety instead of the silver variety, and began to display them in small containers. The fish were not kept in the containers permanently, but would be kept in a larger body of water, such as an outdoor pond, and only for special occasions at which guests were expected would they be moved to the much smaller container.

In 1162, the Empress of the Song Dynasty ordered the construction of a pond to collect the red and gold variety of those carp. By this time, people outside the imperial family were forbidden to keep goldfish of the gold (yellow) variety, yellow being the imperial color. This is probably the reason why there are more orange goldfish than yellow goldfish, even though the latter are genetically easier to breed.

The occurrence of other colors (apart from red and gold) was first recorded in 1276. The first occurrence of fancy tailed goldfish was recorded in the Ming dynasty. In 1502, goldfish were introduced to Japan, where the Ryukin and Tosakin varieties were developed. 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 were known to symbolize good luck and fortune. It became tradition for married men to give their wives a goldfish on their year anniversary, as a symbol for the prosperous years to come. This tradition quickly died, as goldfish became more available around Europe, thus losing their sacred status. Goldfish were first introduced to North America around 1850 and quickly became popular in the United States.

The wild form of the goldfish is the Prussian carp (Carassius gibelio). Some sources claim the Crucian carp (Carassius carassius) as the wild version of the goldfish. While they are closely related, they can be differentiated by the following characteristics:

• C. auratus have a more pointed snout while the snout of a C. carassius is well rounded.
• The wild form of the Goldfish C. gibelio often has a grey/greenish color, while crucian carps 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.

Varieties of domesticated goldfish

Selective breeding over centuries has produced several color variations, some of them far removed from the "golden" color of the originally domesticated fish. There are also different body shapes, fin and eye configurations. Some 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. However, some variations are hardier, such as the Shubunkin. The main varieties are:

Common goldfish		Black Moor		Bubble Eye
Common goldfish are a type of goldfish with no other modifications from their ancestor, the Prussian carp, other than their color. Common goldfish come in a variety of colours including red, orange/gold, white, black and yellow or 'lemon' goldfish.		The Black moor is a telescope-eyed variety of fancy goldfish that has a characteristic pair of protruding eyes. It is also referred to as popeye, telescope, kuro demekin in Japan and dragon-eye in China.		The Bubble Eye is a small variety of fancy goldfish with upward pointing eyes that are accompanied by two large fluid-filled sacs.
Celestial Eye		Comet (goldfish)		Fantail (goldfish)
Celestial eye goldfish or Choten gan is a double-tailed breed of fancy goldfish that has a breed-defining pair of telescope eyes which are turned upwards, pupils gazing skyward.		The comet or comet-tailed goldfish is the most common variety of fancy goldfish in the United States. It is similar to the common goldfish, except slightly smaller and slimmer, and is mainly distinguished by its long deeply forked tail.		The Fantail goldfish is the western form of the Ryukin that possesses an egg-shaped body, a high dorsal fin, a long quadruple caudal fin, and no shoulder hump.	File:FT2.jpg
Lionhead (goldfish)		Oranda		Pearlscale
The lionhead is a hooded variety of fancy goldfish. This fish is the precursor to the ranchu.		An oranda is a fancy goldfish characterized by a prominent raspberry-like hood encasing its head. The hood or headgrowth (also known as wen) encases the whole head except for the eyes and mouth.		The pearlscale or chinshurin in Japanese, is a spherical-bodied fancy goldfish with finnage similar to the fantail.
Pompom (goldfish)		Ryukin		Shubunkin
Pompoms or pompon or hana fusa are a type of fancy goldfish that have bundles of loose fleshy outgrowths between the nostrils, on each side of the head.	File:Pompom.jpg	The ryukin is a short deep-bodied fancy goldfish with a characteristic hump in the shoulder region.		Shubunkins (朱文金) (translated literally as "red brocade") are a hardy, single-tailed fancy goldfish with nacreous scales, and a pattern known as calico. The shubunkins are of Japanese origin.
Telescope eye		Ranchu		Panda Moor
The telescope eye or demekin is a fancy goldfish characterized by its protruding eyes. It is also known as globe eye or dragon eye goldfish.		The ranchu is a hooded variety of fancy goldfish developed in Japan. It is referred to as the "king of goldfish" by the Japanese.		The panda moor is a fancy goldfish with a characteristic black-and-white color pattern and protruding eyes.
Veiltail
The veiltail is a fancy goldfish which is known for its extra-long, flowing double tail.

Chinese Goldfish classification

In Chinese goldfish keeping, goldfish are classified into 4 main types, which are not commonly used in the West.

• Dragon Eye—Goldfish with extended eyes, e.g. Black Moor, Bubble Eye, and Telescope Eye
• Egg—Goldfish without a dorsal fin. e.g. Lionhead (note that a Bubble Eye without a dorsal fin belongs to this group)
• Wen—Goldfish with dorsal fin and a fancy tail. e.g. Veiltail ("Wen" is also the name of the characteristic headgrowth on such strains as Oranda and Lionhead)
• Ce (may also be called "grass")—Goldfish without fancy anatomical features. This is the type that is usually used in Japanese carnivals, especially for "goldfish scoops".

In ponds

Goldfish coming to the surface of an outdoor pond

Goldfish are popular pond fish, since they are small, inexpensive, colourful, and very hardy. In an outdoor pond or water garden, they may even survive if brief periods of ice form on the surface, as long as there is enough oxygen remaining in the water and the pond does not freeze solid.

Common goldfish, London and Bristol shubunkins, jikin, wakin, comet and sometimes fantail goldfish can be kept in a pond all year round in temperate and subtropical climates. Moor, veiltail, oranda and lionhead can be kept safely in outdoor ponds only in the summer, and in more tropical climates.

Small to large ponds are fine though the depth should be at least 80 cm (30 in) to avoid freezing. During winter, goldfish will become sluggish, stop eating, and often stay on the bottom of the pond. This is completely normal; they will become active again in the spring. A filter is important to clear waste and keep the pond clean. Plants are essential as they act as part of the filtration system, as well as a food source for the fish. Plants are further beneficial since they raise oxygen levels in the water.

Compatible fish include rudd, tench, orfe and koi, but the latter will require specialized care. Ramshorn snails are helpful by eating any algae that grows in the pond. It is of great importance to introduce fish that will consume excess goldfish eggs in the pond, such as orfe. Without some form of population control, goldfish ponds can easily become overstocked. Koi may also interbreed with the goldfish to produce a sterile hybrid fish.

In aquariums

A shiny gold and orange goldfish with a short, bulging body, and very long, flowing fins and tail, facing left

A Fantail goldfish

Like most carp, goldfish produce a large amount of waste both in their faeces and through their gills, releasing harmful chemicals into the water. Build-up of this waste to toxic levels can occur in a relatively short period of time, which is often the cause of a goldfish's sudden death. Because of this, goldfish need a large volume of water in which to live. For common and comet varieties, each goldfish should have about 20 gallons(US) or 75 liters of water. Fancy goldfish (which are smaller) should have about 10 gallons(US) or 37.5 liters per goldfish. The amount of water surface area is also important in determining how many goldfish may live in a container, as water surface area determines how much oxygen diffuses and dissolves from the air into the water. A general rule is have one square foot of water surface area for every inch of goldfish length (370 cm²/cm). If the water is being actively aerated by way of a water pump, filter or fountain, a smaller volume of water is needed.

The goldfish is classified as a coldwater fish, and can live in unheated aquariums at a room temperature comfortable for humans. However, goldfish cannot tolerate rapid changes in temperature (for example in an office building in winter when the heat is turned off at night). The sudden shift in temperature could kill them, especially if the goldfish are kept in a small tank. Care must also be taken when adding water, as the water added may be a different temperature than the water in the tank. Temperatures under about 10°C/50°F are dangerous to fancy varieties of goldfish, though commons and comets can be exposed to slightly lower temperatures without a problem. Extremely high temperatures (over 30°C/86°F) can also be harmful to goldfish. However, higher temperatures may be helpful for fighting protozoan infestations by accelerating the parasite's life-cycle—thus eliminating it more quickly. The optimum temperature for goldfish is around 25°C/77°F.

Like all fish that are kept as pets, goldfish do not like to be petted. In fact, touching a goldfish can be quite dangerous to its health, as it can cause the protective slime coat to be damaged or removed, which opens the fish’s skin up to infection from bacteria or parasites in the water. However, goldfish will respond to pet owners by coming to the surface of the water at feeding time, and can be trained or acclimated to taking pellets or flakes from a human's fingers. The supposed reputation of goldfish dying quickly is often due to poor care amongst uninformed buyers looking for a cheap pet. The true lifespan of a well-cared-for goldfish in captivity can extend beyond 10 years.

If left in the dark for a period of time, a goldfish will turn almost gray. Goldfish have pigment production in response to light, which is almost like our tanning in the sun. Fish have cells called chromatophores that produce pigments which reflects light, and gives coloration. The color of a goldfish is determined by which pigments are in the cells, how many pigments molecules there are, and whether the pigment is grouped inside the cell or is spaced throughout the cytoplasm. So if a goldfish is kept in the dark it will appear lighter in the morning, and over a long period of time will lose its color.

Wild goldfish and relationship to Prussian carp

Fancy goldfish are unlikely to survive for long in the wild as they are handicapped by their bright fin colors; however it is not beyond the bounds of possibility that such a fish, especially the more hardy varieties such as the Shubunkin, can survive long enough to breed with its wild cousins. Common and comet goldfish can survive, and even thrive, in any climate in which a pond for them can be created. Introduction of wild goldfish can cause problems for native species. Within three breeding generations the vast majority of the goldfish spawn will have reverted to their natural olive color. Since they are carp, goldfish are also capable of breeding with certain other species of carp and creating hybrid species.

Research by Dr. Yoshiichi Matsui, a professor of fish culture at Kinki University in Japan, suggests that there are subtle differences which demonstrate that while the Prussian carp is the ancestor of the goldfish, they have sufficiently diverged to be considered separate species.

Feeding

Various types of prepared fish food

See also: Fish food

Like most fish, goldfish are opportunistic feeders and do not stop eating of their own accord. When an excess of food is offered, they will produce more waste and feces, partly due to incomplete digestion of protein. Overfed fish can sometimes be recognized by feces trailing from their cloaca. Goldfish need only be fed as much food as they can consume in three to four minutes, and no more than twice a day. Contrary to some common belief, extreme overfeeding will not increase the size of the fish but can actually be fatal, typically by bursting of the intestines. This happens most often with selectively bred goldfish, which have a convoluted intestinal tract as opposed to a straight one in common goldfish. Novice fishkeepers who have newly purchased ryukin, fantail, oranda, lionhead or other fancy goldfish will need to watch their fish carefully for a few days, as it is important to know how much the goldfish will eat in a couple minutes of time.

Special goldfish food has a lower protein and higher carbohydrate content than conventional fish food. It is sold in two consistencies—flakes that float at the top of the aquarium, and pellets that sink slowly to the bottom.

Goldfish enthusiasts will supplement this diet with shelled peas (with outer skins removed), blanched green leafy vegetables, and bloodworms. Young goldfish also benefit from the addition of brine shrimp to their diet. As with all animals, individual goldfish will display varied food preferences. In any case, it is better to feed them a variety of foods listed above.

Behavior

Behavior can vary widely both because goldfish are housed in a variety of environments, and because their behavior can be conditioned by their owners.

Scientific studies done on the matter have shown that goldfish have strong associative learning abilities, as well as social learning skills. In addition, their strong visual acuity allows them to distinguish between specific humans. It is quite possible that owners will notice the fish react favorably to them (swimming to the front of the glass, swimming rapidly around the tank, and going to the surface mouthing for food) while hiding when other people approach the tank. Over time, goldfish should learn to associate their owners and other humans with food, often "begging" for food whenever their owners approach. Auditory responses from a blind goldfish proved that it recognized one particular family member and a friend by voice, or vibration of sound. This behavior was remarkable because it showed that the fish recognized the vocal vibration or sound of two people specifically out of seven in the house. Goldfish are gregarious fish that show schooling behavior, as well as displaying the same types of feeding behaviors. Goldfish may display similar behaviors when responding to their reflections in a mirror.

Goldfish that have constant visual contact with humans also seem to stop associating them as a threat. After being kept in a tank for several weeks, sometimes months, it becomes possible to feed a goldfish by hand without it reacting in a frightened manner.

Goldfish have behaviors, both as groups and as individuals, that stem from native carp behavior. They are a generalist species with varied feeding, breeding, and predator avoidance behaviors that contribute to their success in the environment. As fish they can be described as "friendly" towards each other, very rarely will a goldfish harm another goldfish, nor do the males harm the females during breeding. The only real threat that goldfish present to each other is in food competition. Commons, comets, and other faster varieties can easily eat all the food during a feeding before fancy varieties can reach it. This can be a problem that leads to stunted growth or possible starvation of fancier varieties when they are kept in a pond with their single-tailed brethren. As a result, when mixing breeds in an aquarium environment, care should be taken to combine only breeds with similar body type and swim characteristics.

Memory

In 1994, a public experiment at the Palais de la Découverte science museum showed that goldfish could be trained to recognize and to react to light signals of different colors by using positive reinforcement. More recent research by the School of Psychology at the University of Plymouth in 2003 demonstrated that goldfish have a memory-span of at least three months and can distinguish between different shapes, colours and sounds. They were trained to push a lever to earn a food reward; when the lever was fixed to work only for an hour a day, the fish soon learned to activate it at the correct time. The Discovery Channel's show Mythbusters tested the contemporary legend that goldfish only had a memory span of 3 seconds and were able to prove that goldfish had a longer memory span than commonly believed. The experiment involved training the fish to navigate a maze. It was evident that they were able to remember the correct path of the maze after more than a month. A study at the start of the 2000s showed that fish do actually respond to certain colours, this is most evident when it comes to feeding as fish are also aware of feeding times provided they are fed at around the same time everyday.

Native environment

Goldfish natively live in ponds, and other slow or still moving bodies of water in depths up to 20 m (65 ft). Their native climate is subtropical to tropical and they live in freshwater with a pH of 6.0–8.0, a water hardness of 5.0–19.0 dGH, and a temperature range of 40–106 °F (4–41 °C) although they will not survive long at the higher temperatures. They are considered ill-suited even to live in a heated tropical fish tank, as they are used to the greater amount of oxygen in unheated tanks, and some believe that the heat burns them. However, goldfish have been observed living for centuries in outdoor ponds in which the temperature often spikes above 86 °F (30 °C). When found in nature, the goldfish are actually an olive green color, and will return to this color if domesticated and then released.

In the wild, the diet consists of crustaceans, insects, and various plant matter.

While it is true that goldfish can survive in a fairly wide temperature range, the optimal range for indoor fish is 68–75 °F (20–23 °C). Pet goldfish, as with many other fish, will usually eat more food than it needs if given, which can lead to fatal intestinal blockage. They are omnivorous and do best with a wide variety of fresh vegetables and fruit to supplement a flake or pellet diet staple.

Sudden changes in water temperature can be fatal to any fish, including the goldfish. When transferring a store-bought goldfish to a pond or a tank, the temperature in the storage container should be equalized by leaving it in the destination container for at least 20 minutes before releasing the goldfish. In addition, some temperature changes might simply be too great for even the hardy goldfish to adjust to. For example, buying a goldfish in a store, where the water might be 70 °F (approximately 21 °C), and releasing it into a garden pond at 40 °F (4 °C) will probably result in the death of the goldfish, even if one uses the slow immersion method just described. A goldfish needs a lot more time, perhaps days or weeks, to adjust to such a different temperature.

Because goldfish like to eat live plants, their presence in a planted aquarium can be quite a problem. Only a few of the aquarium plant species can survive in a tank with goldfish, for example Cryptocoryne and Anubias species, but they require special attention so that they are not uprooted. Fake plants are often more durable, but the plant branches can often irritate or harm a fish if it comes in contact with them.

Breeding

Goldfish, like all cyprinids, are egg-layers. They produce adhesive eggs that attach to aquatic vegetation. The eggs hatch within 48 to 72 hours, releasing fry large enough to be described as appearing like "an eyelash with two eyeballs". Within a week or so, the fry begin to look more like a goldfish in shape, although it can take as much as a year before they develop a mature goldfish color; until then they are a metallic brown like their wild ancestors. In their first weeks of existence, the fry grow remarkably fast—an adaptation born of the high risk of getting devoured by the adult goldfish (or other fish and insects) in their environment.

Some scientists believe goldfish only grow to sexual maturity if given enough water and the right nutrition. However, if kept well, they may breed indoors, but not in a small fishbowl. Breeding usually happens after a significant change in temperature, often in spring. Eggs are then separated into another tank, as the parents will likely eat any of their young that they happen upon. Dense plants such as Cabomba or Elodea or a spawning mop are used to catch the eggs.

Most goldfish can and will breed if left to themselves, particularly in pond settings. Males chase the females around, bumping and nudging them in order to prompt the females to release her eggs, which the males then fertilize. Due to the strange shapes of some extreme modern bred goldfish, certain types can no longer breed among themselves. In these cases, a method of artificial breeding is used called "hand stripping". This method keeps the breed going, but can be dangerous and harmful to the fish if not done correctly.

Mosquito control

Like some other popular aquarium fish, such as the guppy, goldfish and other carp are frequently added to stagnant bodies of water in order to reduce the mosquito populations in some parts of the world, especially to prevent the spread of West Nile Virus, which relies on mosquitoes to migrate. However, the introduction of goldfish has often had negative consequences for local ecosystems.

Controversy

The Japanese game of Goldfish scooping

The popular image of a goldfish in a fishbowl is an enduring one. However, some countries have banned the sale of bowls of that type under animal rights legislation due to the risk of stunting, deoxygenation and ammonia/nitrite poisoning in such a small environment. Because of their large oxygen needs and high waste output, the popular goldfish bowls of the past are no longer considered appropriate housing for goldfish.

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 this has since been amended to only prevent goldfish being given as prizes to unaccompanied minors. However, in Rome, Italy, the city passed a law in late 2005, which banned the use of goldfish or other animals as carnival prizes. Rome has also banned the keeping of goldfish in "goldfish bowls", on the premise that it's cruel to the fish to live in such a small, confined space.

In Japan, during summer festivals and religious holidays (ennichi), a traditional game called goldfish scooping is played, in which a player scoops goldfish from a basin with a special scooper. Sometimes bouncy balls are substituted for goldfish.

Although edible, goldfish are rarely eaten. A fad among American college students for many years was swallowing goldfish as a stunt and as an initiation process for fraternities. The first recorded instance was in 1939 at Harvard University. The practice gradually fell out of popularity over the course of several decades and is no longer continued.

See also

• Aquarium - different types of aquariums
• Carp
• Cyprinid - other members of carp family
• List of freshwater aquarium plant species for plant species compatible with a goldfish

References

• "Carassius auratus". Integrated Taxonomic Information System. 5 October. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)
• Froese, Rainer, and Daniel Pauly, eds. (2004). Carassius auratus auratus in FishBase. September 2004 version.
• The Common Goldfish by Les Pearce
• Background information about goldfish
• Carassius auratus
• Article on the oldest Goldfish, Goldie.

External links

A distorted view of a goldfish in a goldfish bowl

Varieties

• Goldfish Pages - Hobbyists web site that provides information on goldfish standards, goldfish varieties and goldfish care.
• Goldfish varieties: Page 1 Page 2
• Bristol Aquarists' Society - Photographs and descriptions of the different goldfish varieties
• Goldfish Genetics - A resource on the genetics of the goldfish with a focus on the originator, crucian carp, and how their basic genetic package gave rise to the varieties of modern goldfish.

Care

• Kokos Goldfish World - A website dedicated to the care of goldfish with a forum, pictures, information and a friendly community.
• Goldfish Info Great information about caring for goldfish
• Wikibook on goldfish care
• Goldfish Disease
• Fish plants
• Breeding Your Goldfish

Other

• Goldfish anatomy
• Flash-animated external fish anatomy
• Amazing goldfish training