goldfish - Varieties of domesticated goldfish, Goldfish in ponds, In the aquarium, Feeding, Behavior, Native environment, Breeding
Colourful, carp-like, freshwater fish (Carassius auratus), native to weedy rivers and lakes of Eurasia, but now very widely distributed as popular ornamental fish; body length up to 30 cm/1 ft, young fish brownish, becoming golden as they mature; mouth lacking barbels; immense variety of forms have been produced through captive breeding. (Family: Cyprinidae.)
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Carassius auratus (Linnaeus, 1758) |
The goldfish, Carassius 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.
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; By this time, people outside the royal family were forbidden to keep goldfish of the gold (yellow) variety, yellow being the royal color. This probably is the reason why there are more orange goldfish than yellow goldfish, even though the latter are genetically easier to breed.
As time passed, more mutations occurred, producing new color variations, and fancier varieties of goldfish were developed.
In 1611, goldfish were introduced to Portugal and from there to other parts of Europe.
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. 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. The main varieties are:
| Common Black moor Bubble eye Celestial eye Comet Fantail Calico 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. black moor, bubble eye, and telescope eye Egg - goldfish without a dorsal fin. lionhead (note that a bubble eye without a dorsal fin belongs to this group) Wen - goldfish with dorsal fin and a fancy tail.
Goldfish in ponds
Goldfish are popular pond fish, since they are small, inexpensive, colourful, and very hardy.
Common goldfish, London and Bristol shubunkins, jikin, wakin, comet and sometimes fantail can be kept in a pond all year round in temperate and subtropical climates. It is of great importance
to introduce fish that will consume excess goldfish eggs in the pond, such as orfe. Koi may also interbreed to produce a sterile new fish.
In the aquarium
The goldfish is usually classified as a coldwater fish, and it can live in an unheated aquarium. Like most carp, goldfish produce a large amount of waste both in their feces and through their gills, releasing harmful chemicals into the water. This also happens because goldfish cannot digest an excess of proteins, unlike most tropical fish. It may be the amount of water surface area, not the water volume, that decides how many goldfish may live in a container, because this determines how much oxygen diffuses and dissolves from the air into the water; If the water is being further aerated by way of water pump, filter or fountain, more goldfish may be kept in the container.
Goldfish may be coldwater fish, but this does not mean they can tolerate rapid changes in temperature. The sudden shift in temperature that comes at night, for example in an office building where a goldfish might be kept in a small office tank, could kill them, especially in winter. Conversely, temperatures over 25 °C (77 °F) can be extremely damaging for goldfish (this is the main reason why they shouldn't be kept in tropical tanks).
The popular image of a goldfish in a small fishbowl is an enduring one.
The supposed reputation of goldfish dying quickly is often due to poor care amongst uninformed buyers looking for a "cheap" pet.
Fancy goldfish are unlikely to survive for long in the wild as they are handicapped by their bright fin colors; 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 crucian carp is the ancestor of the goldfish, they have sufficiently diverged to be considered separate species.
Feeding
Like most fish, goldfish are opportunistic feeders. 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 ruykin, 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 few minutes of time.
Special goldfish food has a lower protein and higher carbohydrate content.
Goldfish enthusiasts will supplement this diet with shelled peas (with outer skins removed), blanched green leafy vegetables, and bloodworms.
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.
Goldfish also display a range of social behaviors.
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, it becomes possible to "pet" a goldfish on the head, feed it by hand, or even cup a hand around it without it reacting in a frightened manner.
Goldfish have behaviors, both as groups and as individuals that stem from native carp behavior. 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.
Native environment
Goldfish natively live in ponds, and other slow or still moving bodies of water in depths up to 20 m (65 ft). However, goldfish have been observed living for centuries in outdoor ponds in which the temperature often spikes above 86 °F (30 °C).
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 fatal intestinal blockage.
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. 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.
Because goldfish like to eat live plants, their presence in an 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.
Breeding
Goldfish, like all cyprinids, lay eggs. 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; 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.
Goldfish can only grow to sexual maturity if given enough water and the right nutrition.
Most goldfish can and will breed if left to themselves, particularly in pond settings.
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.
Edibility and cruelty
Although edible, goldfish are rarely eaten.
In many countries, the operators of carnivals and fairs commonly give goldfish away in plastic bags as prizes for winning games. 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.
Killing fish humanely for human consumption or benign purposes (such as putting down an ill fish) is still legal in most countries (provided 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 United Kingdom, it is illegal to sell live fish (including goldfish) as "feeder fish" for consumption by other animals.
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