Introduction
Goldfish scientific Name: Carassius auratus
Common Names of Goldfish: Goldfish, Goldie, Skipper, Blackie, and Bubbles
Goldfish is a fish of water common in domestic fresh ponds and aquariums around the world.
It comes from an Asian goldfish or squid, the golden cyprin (Carassius auratus), so it is close to the common squid, a fish that lives in the fresh, calm and temperate waters of Europe and China. Selective breeding has made it possible to obtain varieties whose morphology has little in common with the golden cyprin.
Research is underway to determine if, and how many, Carassius auratus has evolved into subspecies. In addition, released into the wild, goldfish readily hybridize with other Cyprinids.
Species description
The Carassius auratus wild, or goldfish is a fish color gray golden simple form.
The species has evolved considerably over the centuries in breeding.
Fish red joint is the most common variety. It differs from its wild form. It can reach a size of about 30 to 45 cm. The body is elongated, while the tail and fins are small in relation to the body. It was initially golden, but with the advent of breeding in China it turned red, calico, white or black.
Each variety of goldfish has its own characteristics: the telescope, of Japanese origin, has prominent eyes; those of the sky telescope are turned upwards, etc.
The memory of the goldfish
The goldfish would have a memory of approximately three months, and would be sensitive to colors and sounds.
In France, a popular idea is that goldfish have only three seconds of memory and that they are not sad in their jars. But this turned out to be wrong.
In any case the goldfish would have the memory of pain for at least 24 hours and can be trained to retain the memory of an event for up to three months, according to a study carried out by the University of Plymouth. A subsequent study conducted at the University of Queen’s Belfast confirmed that feels pain and can learn to avoid it in an aquarium where he received electric shocks in some sectors.
They are cold water fish, but they can be kept at temperatures ranging from 1 °C to 27 °C for common goldfish ( 22 °C for spawning). For derivative varieties such as veil tail, telescopes, oranda, lion’s head, bubble eyes … which are more delicate, the temperature must be between 10 °C and 26 °C.
The water should have a rather neutral to alkaline (basic) pH of between 7.0 to 8.0, and a hardness of 5 °d GH to 15 °d GH.
Due to their size, at least 20 cm in length for the selected varieties and up to 50 cm for the classic goldfish, these animals are in great need of swimming space. Classic goldfish are suitable for large bodies of water but, with proper care and equipment, they can live in small ponds, tanks or large aquariums.
In aquariums, large volume tanks are recommended, with a minimum of 50 L per “variety” goldfish and 100 L per common goldfish. As they are gregarious animals, which live in shoals, they must be kept at least by two or three of the same variety, it is therefore necessary to provide at least 100 L at the strict minimum for selected varieties, which will turn out to be tiny when the fish will be adults. The aquarium must also be equipped with powerful filtration (approximately 4/5 times the total volume per hour).
Maintenance in a “ball” or in a small container is unsuitable. The normal life expectancy of a goldfish is about 30 years and it grows considerably… Those kept in small volumes are affected by dwarfism and very often die prematurely. Indeed during a complete cleaning (replacement of all the water) the bacterial fauna participating in the denitrification of the medium is completely destroyed. However, this is essential to maintain certain harmful materials at a level that is not detrimental to the health of the fish. This bacterial population takes about a month to reconstitute.
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Food
This fish is omnivorous. In mixed basins (water and plants) not well populated, it generally finds living and vegetable food. In overcrowded ponds, fish tanks, they will be given as a complement or as a main menu, suitable store-bought food.
The goldfish is said to be “gluttonous” since it can, when it is fed by humans, eat much more than it needs, at the risk of becoming ill. To know how much to give them, you must follow the rule “the right amount is what can be eaten in one to three minutes”. The ration can thus be adapted according to the fish, their size, their number, their appetite, the temperature, etc.
Preferably choose the granules because they flow and do not pollute the water. Avoid dried daphnia, they have no nutritional value, and bread, which swells in their gut and can cause them serious digestion problems.
If their space is not sufficiently planted, it is advisable to complete the menu with greenery (poached salad, spinach, zucchini …) and, if it is not located outside, with live and / or frozen food ( artemia, red bloodworms, mosquito larvae, etc.).
Reproduction
In the spring, when the water reaches 14 to 16 °C, the goldfish are about to reproduce. In the aquarium, it is necessary to lower the temperature during the winter if you want to attempt reproduction because the maturation cycle must go through a phase of dormancy.
The male reaches sexual maturity at two years and the female at three years. Females are rounder and fuller than males when the spawning season arrives. We recognize that they are ready to lay because the belly becomes soft and the genital opening appears prominent. At this time, males easily release milt when handled. They have rough white “wedding buttons” on the operculum as well as on the first ray of the pectoral fins which are often more developed than in females.
Reproduction is called “spawning“. The female, accompanied by several males, leans on the supports (spawning grounds) available to lay eggs. The eggs and milt are released in full water and it is at this time that fertilization must take place. On contact with water, the proteins that cover the egg begin to become sticky, the egg hydrates and swells, and the micropyle closes. Eggs that have not been fertilized at this stage are lost. The eggs then adhere to plants and surrounding surfaces. The incubation can begin. (Eggs that are too clumped together, fallen to the ground or in a poorly oxygenated cubicle are very likely to be lost for lack of pathogenic ..).
The term embryogenesis is proportional to the temperature and may require from six to three days in water of 16 respectively 24 °C. When hatching, the ends of the digestive system (mouth and anus) of the larva are not yet open, but the latter has a yolk reserve which provides it with the energy and nutrients necessary to complete its formation. .
However, not yet having a swim bladder, the larva sinks and cannot keep in water without making a considerable effort. She therefore seeks to cling to the support she finds. This so-called vesicle resorption period can take two to four days (depending on the temperature).
As soon as it is able, the larva comes to the surface to pick up an air bubble which inflates its swimming bladder and thus allows it to swim normally. From this moment, it must begin to feed (infusoria, rotifers, plant debris …).
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Health
Diseases most often appear because of poor maintenance (too small aquarium, poor filtration, inadequate food, overcrowding, etc.). Goldfish are sold in pet stores in their juvenile form, kept in good condition until they reach their adult size which is around 20 cm. The majority of these animals are placed in jars or aquariums with a very low volume and then develop a form of dwarfism, which results in malformations of organs and significantly shortens their life. In addition, the jars reduce the exchange surface between water and air, which depletes the medium in oxygen. Finally, goldfish are big polluters, and their waste is degraded by bacteria and turns into poison (see nitrogen cycle ). Fish raised under such conditions never reach sexual maturity. Some also consider the keeping of goldfish in round jars as ill-treatment; the city of Rome has even banned their use.
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