Aquarium fish: Goldfish (Carassius auratus)
Size: 10 – 20 cm
Origin: Asia
Water temperature: 16-24 ° C
Aquarium volume: 80 l

Goldfish (Carassius auratus) – undoubtedly the most popular and world-famous aquarium fish.Its breeding began in China around the 7th century AD. Goldfish is actually a colloquial, general name for numerous breeding varieties of the population of one of the subspecies of the ornamental crucian carp. The veil (Veiltail) is its characteristic variety with elongated fins.


It did not occur in nature in the wild form. It is the result of over 1000 years of selection in China, followed by Japan, Vietnam and several other countries.

As a result of deliberate (releasing fish into wild reservoirs) or accidental introduction (escapees from breeding), it appeared in inland waters of many countries around the world, in some of them creating permanent populations.

Characteristics and disposition

Goldfish are mainly bred in garden or park ponds and ponds, where they can grow up to 30 cm in length. In aquariums they reach 10 to 20 cm. The most famous varieties are: shubunkin, veil, tiger veil, telescope, comet, fish egg, black telescope, lion’s head, skygrazer and nymph. At exhibitions, veils are assessed on the basis of the required classical body and fin proportions.

Gender of young fish is difficult to distinguish. Adult females are usually slightly larger and rounder. In the male during the breeding period, a rash appears on the gill covers. Professional breeders use artificial spawning for these fish, which is more effective and allows for tight reproduction control. Gregarious, vigorous and resilient fish, unfortunately due to the greater tolerance of pollution and lower temperatures, they are often kept alone in a tight, small and unfiltered glass ball, where they often get sick and live for a short time.

Nutrition and feeding

They accept all available frozen, live, vegetable and dry foods. A varied diet will keep them in the best condition. At temperatures below 9 ° C, goldfish hibernate and do not eat. Kept in home aquariums, they must be fed throughout the winter.


The recommended minimum for one individual is an aquarium with a capacity of 80 liters , and for each subsequent one we should add about 35 liters.

Goldfish and all its varieties are cold-loving, but those with elongated fins and veils cannot tolerate temperatures below 13 ° C and should not be kept outside. The optimal temperature for delicate varieties is 18-24 ° C. They are fish quite resistant to water pollution, but at the same time they dirty it incredibly quickly, which is why the tank must have a very efficient filter. Regular (weekly) fresh water changes (approx. 25%) are also recommended.

In such conditions, goldfish have a chance for proper and healthy development as well as a long life. They eagerly dig in the ground, so a good choice will be a gravel ground and floating plants, as well as durable, broad-leaved species attached to decorative elements. It is best to keep them in a species aquarium or with other coldwater fish. A Chinese Cardinal will be a good company .


Reproduction is not very common in aquariums.

Selected adult individuals aged about 3-4 years are placed in tanks in pairs or groups with a predominance of males. A distinct feature of males is a spawning rash on the gill covers during this period. The bottom of the tank should be planted with plants and dry branches or synthetic lining. It is also worth shading the aquarium a bit with floating plants. The fish spawn after periodically cooling the water.

They will be encouraged to reproduce by increased temperature and a high-protein diet. The water parameters are rather not important for these fish, but it must be clean and well-oxygenated. The eggs are most often laid near the bottom among the vegetation. The roe is tiny and very sticky. At a temperature of about 25 ° C, hatching takes about 3 days.

After spawning, the adult specimens should be separated. Initially, the young can be fed brine shrimp larvae, plankton and micro-sized artificial food, in later stages chopped tubs, granulated and flake food.

Experimental research

Goldfish were used as a research object in laboratories. It has been used, inter alia, for research on the behavior of this species in a weightless state with the use of a jet plane that can achieve acceleration greater than 1 g.


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