During the Tang Dynasty —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.
Inthe 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. During the s, 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 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:. 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:. Goldfish are classified into 4 main types by Chinese tradition. These classifications are not commonly used in the West. Goldfish are popular pond fish, since they are small, inexpensive, colourful, and very hardy. In an outdoor pond or water gardenthey may even survive for brief periods if ice forms 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 some hardier 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.
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 ruddtenchorfe and koibut 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. 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.
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.
If the water is being actively aerated by way of a water pumpfilter or fountaina smaller volume of water is needed. The goldfish is classified as a coldwater fishand 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. However, higher temperatures may be helpful for fighting protozoan infestations by accelerating the parasite's life-cycle—thus eliminating it more quickly.
Like all fish that are kept as pets, goldfish do not like to be petted. 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. 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. 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. 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 aquariumand pellets that sink slowly to the bottom. Goldfish enthusiasts will supplement this diet with shelled peas with outer skins removedblanched green leafy vegetablesand 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 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. Blog Accueil. Conseil de pro : les carpes koï blanches ont-elles besoin d'une autre nourriture que celles qui sont rouges et blanches ou de couleur orange?
Retour au sommaire. Partagez cet article avec vos amis! Heiko Blessin. Votre avis nous est précieux. La biologie des chromatophores est également utilisée pour modéliser certaines affections humaines, comme le mélanome ou l' albinisme.
Récemment, on a découvert que le gène responsable de la spécificité des mélanophores dans la variété dorée de Poissons zèbresSlc24a5avait un équivalent chez l'humain qui présente une forte corrélation avec la couleur de la peau [ 29 ]. Les chromatophores sont aussi utilisés comme biomarqueur de la cécité chez les espèces à sang froid, car les animaux présentant certains types de déficience visuelle ne parviennent pas à réaliser l' homochromie [ 25 ].
On pense que des homologues chez l'humain des récepteurs intervenant dans la translocation de pigment des mélanophores interviendraient dans la suppression de l' appétit et dans le bronzageen faisant des cibles attrayantes pour la recherche pharmaceutique [ 30 ].
Par conséquent, les compagnies pharmaceutiques ont développé des tests biologiques pour identifier rapidement les composés bioactifs potentiels en utilisant les mélanophores d'un crapaud africain Xenopus laevis [ 31 ]. D'autres scientifiques ont développé des techniques pour utiliser les mélanophores comme biosenseurs [ 32 ]et pour une détection rapide de la coqueluche basée sur la découverte que la toxine de la coqueluche bloque l'agrégation de pigment dans les mélanophores de poissons [ 33 ].
Des applications militaires potentielles concernant les changements de couleur des chromatophores ont été proposées, principalement comme type de camouflage actif [ 34 ].
Les céphalopodes de la sous-classe des Coleoidea ont des 'organes' multicellulaires complexes qu'ils utilisent pour changer de couleur rapidement. C'est particulièrement notable chez les calmarsseiches et pieuvres aux couleurs vives. Chaque unité de chromatophores est composée d'une seule cellule pigmentaire et de nombreuses cellules musculairesnerveuseset gliales entre autres des cellules de Schwann [ 35 ].
À l'intérieur de la cellule du chromatophore, des granules de pigments sont enfermés dans un sac élastique, le sacculus cytoélastique. Pour changer de couleur, l'animal déforme le sacculus pour qu'il change de forme ou de taille par contraction musculaire, modifiant ainsi sa transluminescencesa réflectivité ou son opacité. Ce mécanisme diffère de celui rencontré chez les poissons, amphibiens et reptiles, car il ne fait pas intervenir une translocation des vésicules de pigment à l'intérieur de la cellule mais un changement de forme du sacculus.
Cependant l'effet est le même. Les poulpes actionnent leurs chromatophores par vagues, obtenant une manifestation chromatique complexe et de rapides changements de couleurs.
On pense que les nerfs commandant les chromatophores seraient situés dans le cerveau, dans une position similaire aux chromatophores qu'ils contrôlent. Cela signifie que l'ordre dans lequel s'effectue le changement de couleur correspond à l'ordre dans lequel se fait l'activation neuronale.
Ceci expliquerait pourquoi le changement de couleur se produit par vagues, parce que les neurones sont activés l'un après l'autre [ 36 ].
Comme le caméléon, les céphalopodes utilisent le changement de couleur dans leurs interactions sociales. Ils sont également parmi les plus compétents en matière d'homochromie, ayant la capacité d'adapter leur couleur et leur texture à l'environnement local avec une précision remarquable. Des chromatophores peuvent aussi être trouvés dans la membrane des bactéries phototrophes.
Utilisés principalement pour la photosynthèseils contiennent des pigments de chlorophylle bactérienne chlorophylle a et d et des caroténoïdes [ 37 ].
Chez les bactéries pourpres, par exemple Rhodospirillum rubrumles antennes collectrices sont intrinsèques aux membranes chromatophores. Cependant, chez les bactéries Chlorobiaceaeelles sont arrangées sous forme d'antennes collectrices spécialisées, les chlorosomes [ 38 ]. Un article de Wikipédia, l'encyclopédie libre. Descrizione di un particolare sistema di organi cromoforo espansivo-dermoideo e dei fenomeni che esso produce, scoperto nei molluschi cefaloso.
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