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Goldfish
Conservation status
Template:StatusSecure
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. It may grow to a maximum length of 23 inches (59 cm and a maximum weight of 6.6 pounds (3.0 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 will only live six to eight years because owners keep them in tanks under the size of 20 US gallons (150 litres).

History

During the Tang Dynasty, it was popular for Chinese ponds to have carp. As the result of a genetic mutation one of these carp displayed "gold" (actually yellowish orange) rather than silver coloration. This mutation is associated with a dominant gene which also makes the breeding of this trait rather easy. The gold-coloured strain became popular for keeping in containers. Afterwards, the people began to breed the gold variety instead of the silver, and began to keep them in small containers to watch.

In 1162 CE, the empress ordered the building of a pond to collect the red and gold variety of those carp. By this time people outside the royal family were forbidden to keep gold fish. An order was given to the keepers to kill all fish that were gold in color because it offended the court, since this itself was the royal color. This is why there are more orange goldfish than yellow goldfish, even though genetically yellow is easier to breed.

As bred in captivity, more mutations occurred producing more colours and fancy goldfish appeared. According to old books, the occurrence of other colours were first recorded in AD/CE 1276. The first occurrence of fancy tailed goldfish was recorded in the Ming Dynasty. In AD/CE 1502, goldfish were introduced to Japan, where the the Ryukin and Tosakin varieties were developed.

In AD/CE 1611, Goldfish were introduced to Portugal and from this starting point they were introduced to other parts of Europe. The goldfish was finally introduced to North America in AD/CE 1874.

Aquarium conditions

The goldfish is quite hardy which accounts in part for its popularity. Their supposed reputation in some areas for dying quickly is often due to poor care amongst uninformed buyers, especially children, looking for a "cheap" pet. The goldfish 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.

Like most carp, goldfish produce a large amount of waste both in the feces and through their gills, releasing harmful chemicals in the water. This also happens because goldfishes cannot digest an excess of proteins, unlike most tropical fish. Build-up of this waste to toxic levels can occur in a relatively short period of time, often the cause of a fish's sudden death. Although goldfish were historically displayed in small "goldfish bowls", a healthy and happy adult goldfish requires at least 40 US gallons of water in order to live a full life. In fact, for single tailed varieties, such as commons or comets, it may even become necessary to have 55 gallons (for adult fish). Other goldfish experts say that it is the amount of water surface area, not the water volume, that decides how many goldfish may live in a container; one square foot of water surface area for every inch of goldfish length (370 cm²/cm). For example, if you had 3 goldfish of length 4 inches each, you might need 12 square feet of water surface area. Surface area is an approximate measure of how much oxygen may be absorbed into the water from the air. If the water is being further aerated by way of water pump, filter or fountain, more goldfish may be kept in the container.

An important thing to remember is that airstones do not increase the amount of dissolved oxygen in the water. You cannot simply "pump" air into the water. Rather, the ripples they create at the surface of the water increase the surface area and therefore facilitate oxygen exchange at the surface of the tank. For the beginner aquiring a goldfish, the best advice that can be given is to get a 20 gallon long tank, these are typically inexpensive, have a huge surface area, and will be a suitable fish home for over 2 years. Beginner filtration can simply be provided by a box filter hung over the back of the tank, though filtration should be rated for 60+ gallons, as the ammonia levels produced by goldfish are much higher than those produced by the tropical fish fliters are typically rate d for. It is also imperative that adequate biological filtration is provided, as the breakdown of nitrates occurs much more slowly at the colder temperatures goldfish are kept at. One useful compromise is to keep the aquarium heated to a constant 72 F, as this temperature keeps the fish active while at the same time aiding bacterial growth.

In the end, it may be easier to transfer the goldfish to a pond rather than a 100 gallon tank, as few homes can support the size. This is an area where most serious aquaculturists will agree, ponds are superior to tanks in the long run for goldfish.

Starting Aquarium

For many goldfish owners, the discovery that their cute little fishy will eventually grow into a giant carp can come as a bit of a surprise. Building a goldfish pond or aquiring a 55+ gallon tank is usually more of an investment than most pet owners were expecting. Thankfully there are inexpensive ways to keep goldfish in more humane conditions until such an environment can be arranged for them. One simple trick is to construct an emergency home for them out of a large plastic container. Any 60+ quart plastic box will do, simply rinse it well with water, fill 3/4 of the way, add water conditioner, and allow it to sit overnight before adding the fish. At 3/4 these containers are usually holding about 12~15 gallons of water, and will house your fish much better than a small bowl. Simply change 20% of the water twice a week (replacing with declorinated aged water) and use an aquarium vacuum to clean any dropping off of the bottom during water changes.

A more ideal eventual solution for the goldfish owner on a budget would be to get a 20 gallon long tank. These measure 30" x 12" x 12" and have a much larger surface area than a ten gallon tank. Increasing tank size is usually exponentially more expensive, but for goldfish the most important factor is surface area. The 20 gallon long is the smallest appropriate tank, and the fish will be much happier here than in the standard 10 gallon.

Starting filtration should be provided by a box filter that hangs on the back of the tank. Undergravel filters have their uses, but they are inappropriate in a goldfish tank as they will quickly clog with detrious. Another excellent arguement against undergravel filters is that the beneficial bacteria can sometimes die off, yet the filter will still appear to be working. The resulting spike in nitrates is often enough to kill every fish in the tank. Canister filters are another excellent choice, but usually well outside the budget of a beginning aquaculturist. Wet-dry and protein skimmer options are usually reserved for marine aquariums, so it would be extreme overkill to use them here. Simply put, the best option is to purchase a box filter rated for twice the volume of your tank, as coldfish produce copious amounts of waste due to their large size.

Lighting is the one area where someone on a budget can avoid investing money initially. Goldfish need day and night cycles to be healthy, but for tanks under 29 gallons the room lights will be sufficient, at least temporarily. Another excellent area to save money is on the full hoods often sold at a great cost than the tanks themselves at the pet store. A much more economical cover for the tank can be constructed out of the plastic mesh backing used for making loop-and-stitch rugs. This can be easily found at any craft store, and can be cut to fit the filters for your tank. Suitable covers can also be constructed out of particle board, which can be found at any hardware store.

One last point that should be made for beginning goldfish owners is on the use of a heater. Goldfish may be coldwater fish, but this does not mean they can tolerate rapid changes in temperature. The sudden shift in temperature the comes at night, for example in an office building where a goldfish might be kept in a small office tank, could do them in, especially in winter. Therefore I recommend a tank heater be set to 68 to 72 degrees F and left in the tank year round. This is especialy important for fancy varieties of goldfish, as they are less hardy than their breathern.

Tips on Care

There exists a great deal of conflicting information on the best way to care for a goldfish, or rather, on the best feasable ways to care for one. The ultimate best solution would be to build an indoor pond, as this would provide the benefits of an outdoor pond without the risk presented by racoons, kingfishers, children, and weather. As for indoor care, there are a few general tips that should be noted.

• Get a quality mechanical filtration system rated for at least twice the volume of your tank. Goldfish produce copious amounts of waste, and this must be dealt with to prevent ammonia spikes.

• Don't use undergravel filtration, these systems require up to six months to establish, and goldfish produce far too much waste. The filter plate will clog with detrious and become useless. Not only that, but these systems are only really effective in tanks under 40 gallons, while most goldfish pairs or treos will need to be moved to 55+ gallon tanks by the time they are two years old.

• Floating pellets, and eventually floating pond pellets are one of the best staple foods to feed to your fish. Uneaten food can be removed easily, the fish have no trouble finding the food before it dissolves, and it is much easier to measure out an appropriate amount of food for someone who is tank sitting.

• Starting with a twenty gallon long tank is fine. While you will eventually have to upgrade to a 55+ gallon tank, it is best for the beginner to have a tank that doesn't create additional problems. Larger tanks require more planning, much more intial invesment, and a bit of a mechanical inclination in setting it against the right walls & floor joists of the home, setting up large filtration systems, and dealing with emergencies. It is also nice in the long run to have the twenty gallon tank to use in case of emergency (such as a bigger tank breaking) or as a hospital/quarantine tank.

• Don't skimp when purchasing filtration for your tank. It is nice to plan your filter so that when you move to a larger tank the filter can handle it as well. An excellent idea when moving from a smaller (10~20 gallon) to a medium (37~55 gallon) tank is to use your old filter, and add an additional identical unit on the opposite end of the tank. Two medium size mechanical filters working in conjunction will do wonders for your water quality, as well as ensure that if a filter were to break, there is at least some filtration until a replacement can be obtained.

• Air pumps are becoming outdated for most standard filtration setups. Air-driven mechanical filters are simply not powerful enough to deal with larger tanks, and should be reserved for fry tanks. The noise of most air pumps is also annoying. Most decorations driven by these air pumps do little to improve the oxygenation of the water. Another simple arguement against the air pump is that it does not deal with the problem of tank overcrowding - if fish are gasping for air (lack of dissolved oxygen) is it almost always better to remove fish from the tank rather than resort to gimmicks to try and increase the air. You never want your fishes lives to depend on an electrical device being able to run constantly, as in the event of a failure their lives would be endangered.

• Lastly, keep the tank cold, goldfish cannot be mixed with tropical fish, and indeed it is not even a good idea to mix them with other fish. Most catfish that can be kept in coldwater get too big (plectos) to keep in the tank, and they are a danger to the goldfish. Numerous accounts can be found of cases where a goldfish was injured, and a catfish will take a liking to sucking on the wounds. There are also a few horror stories of celestial goldfishes eyeballs being sucked out by a wandering algae eater. The bottom line, don't mix.

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 and they live in freshwater with a 6.0–8.0 pH, a water hardness of 5.0–19.0 dGH, and a temperature range of 40 to 106 °F (4 to 41 °C) although they will not survive long at the higher temperatures. Indeed, 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 as well as the heat burns them. 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 plant matter.

While it is true that goldfish can survive in a fairly wide temperature range, the optimal range for indoor fish is 68 to 75 °F (20 to 23 °C). Pet goldfish, as with many other fish, will usually eat more food than it needs if given, which can lead to a 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 hoping to release it into your garden pond at 40 °F (4 °C) will probably result in the death of the goldfish, even if you use the slow immersion method just described. A goldfish will need a lot more time, perhaps days or weeks, to adjust to such a different temperature.

Because the goldfish likes to eat live plants, keeping it with plants in an aquarium can be quite a problem. Only a few of the aquarium plant species can survive in a tank with goldfishes, for example Cryptocoryne and Anubias species, but they require special attention so that they are not uprooted.

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 more robust variations such as the Shubunkin are more hardy. The main varieties are:

• Common
• Black Moor
• Bubble Eye
• Celestial Eye
• Comet
• Fantail
• Lionhead
• Oranda
• Pearlscale
• Pompom
• Ryukin
• Shubunkin
• Telescope Eye
• Ranchu
• Panda Moor
• Veiltail

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
• Ce (may also be called "grass") - Goldfish without anything fancy. Which is the type that is used for Japanese carnivals, especially for "goldfish scoops".

Goldfish in ponds

Goldfish can also be kept in ponds. Common goldfish, London and Bristol shubunkins and comet can be kept in a pond all year round in Britain. Bristol shubumkin, fantail, veiltail, oranda and lionhead are only safe in the summer. Goldfish make great pondfish. They are small, inexpensive, very hardy and add much colour to the pond.

Small to large ponds are fine though the depth should be at least 80 cm (30 in) to avoid freezing. During winter golfish will become slow, stop eating and often stay on the bottom. This is completly normal and in spring they will become active again. A filter is important to clear waste and keep the pond clean. Plants are not essential but can be added. Oxygenating plants are beneficial since they raise oxygen levels.

Compatible fish include rudd, tench, orfe and koi but the latter will require specialised care. Ramshorn snails are helpful by eating any algae that grows in the pond.

Wild Goldfish and relationship to Crucian carp

Fancy goldfish are unlikely to survive for long in the wild as they are handicapped (for example by fin colors), however it is not beyond the bounds of possiblilty that such a fish, especially the more hardy varieties such as the Shubunkin, could survive long enough to breed with its wild cousins.

Research by Dr Yoshiichi Matsui suggests that there are subtle differences which demonstrate that while the crucian carp is the ancestor of the goldfish, they are not the same fish.

Behaviour

It is often said that goldfish have a memory span 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 consciousness of what has happened on previous occasions, but may not be sure exactly what it was. They can learn to eat from a certain ring inside their tank, or even from their caretaker's hand, because they will remember that there is something good in that area, but might not remember what.

This behavior, or type of learning is an example of classical conditioning. If a predatory animal such as a heron is around, they will likely hide away for quite a while, but they probably do not know what it is they are hiding from; they simply know it is worth avoiding. Goldfish have a sense of time, and in captivity may be able to recognize a set feeding schedule, becoming excited before food even appears. Contrary to the notion that goldfish have poor memory, they will respond to a visit by a predator such as a raccoon, which may completely trash a small pond traumatizing the resident goldfish, which may remain extremely shy and jittery to any approach thereafter.

On the television show MythBusters, Jamie Hyneman and Adam Savage explored the idea by each trying to train goldfish to navigate a maze over a 45-day period. The result was that the fish could definitely be trained to navigate the maze.

Recently, a goldfish has been 'trained' to shoot a ball into a net inside his tank. The owners say that they did it by offering treats to him as soon as he performed the trick.

• Mythbusters fanclub page about this episode

Feeding

Like most fish, goldfish are opportunistic feeders, meaning they will eat whenever food is available, whether they are hungry or not. This habit can be fatal. Their digestive tract can become so jammed with food that the intestines tear open, killing the fish. Also, an excess of food means more waste and feces, which pollute the tank. Goldfish should only be fed as much food as they can consume in 3 to 4 minutes, and no more than twice a day.

A good way to tell if your goldfish is being properly fed is to look as their faeces. They should be short and chunky, the same color as the food the fish is eating. Long strings of waste that trail behind the fish as they swim could be a sign of over-feeding.

Care has to be taken when choosing the right food for them, because goldfishes need less protein (which they cannot digest in excess) and more of the easy to digest carbohydrates. However, specialised food for them can be found on the market.

The oldest known goldfish was called Fred, and lived to 49 years.

Breeding

Goldfish, like all cyprinids, are egglayers. They produce adhesive eggs which attach themselves to aquatic vegetation. The eggs hatch within 48-72 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 be as much as a year before they take their mature goldfish color, until then they are a metallic brown like their wild forebears. In their first weeks of existence, the fry grow remarkably fast; an adaptation borne of the high risk of getting devoured by the adult goldfish (or other fish and insects) in their environment.

Goldfish can only grow to sexual maturity if given enough water and the right nutrition. However if kept well, they may breed indoors. Breeding usually happens after a significant change in temperature, often in spring. Eggs should then be 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

In certain parts of the world, goldfish and other carp are frequently added to stagnant bodies of water in order to reduce the mosquito populations, especially now with the arrival of West Nile Virus which relies on mosquitoes to migrate. Their introduction often had unfortunate consequences for local ecosystems, however.

Edibility and cruelty

Although edible, the goldfish is 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.

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. 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 space.

While being otherwise unkind to fish may now be prohibited, killing fish (humanely) for human consumption or benign purposes (such as putting down an ill fish) is still legal in most countries (provided of course that the fish is not a protected fish caught in the wild, a fish in protected reserves or in water where the person concerned has no right to collect the fish). In the UK it is understood to be illegal to sell live fish, such as goldfish, as "feeder fish" for consumption by other fish or animals

Never flush a dying fish down the toilet, clorine poisoning is not a humane way to kill a goldfish. If a goldfish must be put down (get an expert opinion before you do this) using some kind of tranquilizer to render the fish unconscious, and then freezing it is the most humane way to end its life. However, a well cared for goldfish should never have to be put down. Most diseases can be prevented by avoiding overcrowding and using proper filtration.

See also

• Cyprinid - other members of carp family
• List of freshwater aquarium plant species for plant species compatible with a goldfish

External links

• Goldfish Utopia - Online Goldfish Forum, Information, And A Goldfish Store.
• GoldFish Queen - The goldfish blog regarding importing goldfish from GoldfishQueen's farm in China. There are lots of introduction with photographs regarding more than 100 different goldfish varieties updating everyday.
• Bristol Aquarists' Society - Photographs and descriptions of the different goldfish varieties

• Goldfish on DMOZ - Goldfish directory
• 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.
• 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'
• Frequently asked questions about goldfish
• Breeding Your Goldfish
• German Specialist in Fancy Goldfish and Fishhealth, with Forum and large Picture-Gallery
• http://www.kokosgoldfish.com/disease.html
• Aquarium Filter Types
• Amazing goldfish training

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

• Animals kept as pets
• Carp
• Cold-water aquarium fish
• Cyprinidae
• Fishkeeping
• Goldfish