Japanese fish and their characteristics

Koi fish farming is attributed to Niigata Prefecture, which is considered "the house of koi". For its part, ornamental breeding is attributed to Koriyama, where the first goldfish breeders for recreational use were installed.

Aquaculture is an ancestral technique that has its origins in Asia and thanks to it it has been possible to domesticate for the first time several species of fish. At first this method was used for production and consumption purposes, but soon changed to breed organisms with beautiful colors. Thanks to this, some Japanese fish are famous, because their splendid characteristics attract attention.

Although the fish that are called Japanese are not native to Japan, they are known as such because in this country their ornamental use began. In other words, selective crossing to obtain the typical colors of these organisms occurred thanks to the Japanese. Keep reading and learn more about the characteristics of these beautiful fish.

Characteristics of Japanese fish

Japanese fish have become the emblem of that country, as they are usually recognized for the number of varieties they present. These animals were used as food in the beginning, because in this region the resources of animal origin were scarce. As time passed, some breeders became aware of their beautiful colors and began to cross them selectively.

Specifically, the fish that are referred to as Japanese are koi carp and goldfish. Both organisms belong to the same group of animals (Cyprinidae), which are closely related to the common carp (Cyprinus carpio). These specimens share distinctive characteristics that confirm their kinship. Some of them are the following:

Great resistance to the environment: this group exhibits a great resistance to different temperatures, conditions and chemical parameters of the water. For this reason, Japanese fish are usually taken as an excellent pet or an organism for production.

Elongated oval body: Typically, these fish exhibit an oval body that lengthens as they grow. In the case of the koi fish it is observed a little wider, while the specimens of the goldfish are flatter.

Body of large sizes: the specimens can reach measures of up to 80 or 90 centimeters in length. This characteristic is not usually taken into account, because the growth of each individual depends on the size of your aquarium or pond.

Bright and diverse colors: thanks to domestication and selective crossing, there is a great diversity of colors and shapes in Japanese fish.

Very obvious scales: as with common carp, the ornamental forms of Japanese fish exhibit scales that are very evident. This feature confirms the physical similarity they have with their closest relatives (carps).

As mentioned at the beginning, Japan is not the country of origin of koi fish or goldfish. Despite this, they are called "Japanese" because in this place the main variants that exist in the world were created.

Koi fish (Cyprinus carpio koi)

These specimens are a variety of common carp, which has its origin in Asia and Europe. At first, carp was raised as a food for the population, since it was easy to raise and maintain. For their part, the Japanese took advantage of rice crops to produce these fish, as the flooded areas served as ponds.

As time went on, farmers realized that some fish had a brighter coloration, which made them easy prey for predators. For this reason, they began to remove them and separate them from the rest, since otherwise they lost their supplies. At some point, the colors of the animal began to attract attention, so selective breeding was initiated to transform it into the koi fish.

Characteristics and varieties of koi fish

The koi fish is a fairly long and heavy organism, as it usually exceeds 60 centimeters in length with a mass of 40 kilograms. These traits make it very difficult to have in small aquariums, so outdoor ponds are usually used to breed them. Thanks to the fact that they resist well to different temperatures and water conditions, it is not necessary to take meticulous care of their habitat.

As for its coloration, the various selective crosses have led to the appearance of many variants, so there are different types of koi fish today.

Among the most common we have the following:

• Kawarimon: they are specimens with non-metallic colors that have different patterns. They can exhibit a single tone or more than one, so they have a huge variety.
• Bekko: individuals of this type have a red, white or orange skin with several black spots.
• Goshiki: these specimens have a white body with a black "grid" pattern, which makes the scales black in their center, but white at the edge. In addition to this, they have several red-orange spots that shine a lot.
• Koromo: they are the product of the crossing of koi fish type asagi and kohaku, so they keep the body white, but with red or black spots and quite obvious scales.
• Shusui: exhibit a combination of red, blue, black and white colors, which highlight their back with dark tones. The color patterns are a little different between each specimen, but they usually respect the presence of a white head with colored spots on the rest of the body.
• Asagi: These fish feature a pattern of blue and gray tones on the back, while their head has a white spot above. In addition, both the fins and part of the body have the typical orange coloration of the koi, but with different patterns or in the form of spots. The scales of this type of koi are more evident than normal.
• Gin-Rin: these organisms have a skin with bright silver and gold colors, so their shape is myy striking.
• Showa: These individuals exhibit a pattern of large red, white and black spots all over the body.
• Tancho: these specimens are quite peculiar, because they do not have so many colors. They are characterized by having a single orange-reddish spot on the head, which does not usually extend to the back. For its part, the body exhibits a uniform silver or gray hue in its entirety.
• Kohaku: this type of koi has a white body with very well-defined red spots, which usually have uniform and attractive contours.

The goldfish (Carassius auratus)

Goldfish have a different history, because when they arrived in Japan, they were already ornamental fish. Prior to the Second World War, China maintained close trade relations with this country, so it was normal for animals of this type to arrive. Thanks to this, they were very quickly accepted by royalty and the elite of society, which made the species popular at the time.

Once the Second World War began, Japan went through a period of isolation, so trade was very reduced. This caused a shortage of goldfish, which led to the appearance of the first breeders in the country. This also allowed new varieties to be created that were unique to the nation.

Although China was the country where goldfish were domesticated and originated, the appearance of different varieties was thanks to Japan. These fish became popular by easily raising the species, which greatly reduced their costs in the market. In this way, when trade was restored, goldfish became even more famous thanks to the Japanese.

Characteristics and varieties of goldfish

The goldfish is an organism that is usually quite small, since its normal size is between 15 and 20 centimeters. Despite this, these animals can reach more impressive sizes, because in larger habitats they manage to exhibit sizes of maximum 90 centimeters in length.

The body of this fish is quite similar to that of a carp, with the difference that its fins are more elongated and present fascinating colorations. However, this depends on the variety that is spoken, since there are remarkable distinctions between each of them.

Listed below are some common varieties of goldfish:

• Bubble: It is characterized by carrying two large sacs under its eyes, which are vesicles with liquids that look like bubbles. In addition, these fish do not exhibit dorsal fin, but their tail is usually a little more elongated than that of other varieties.
• Celestial: these specimens are characterized by the shape and position of their eyes, which look like protrusions next to their face. The coloration of these organisms can vary between yellow, orange, red and white.
• Eggfish: they have a fairly oval body and without a dorsal fin, which enhances their peculiar shape.
• Comet: it is similar to the common variety, but with the difference that its orange-red body has white spots and fins. In addition, their fins are larger, so they simulate a kind of "comet tail".
• Oranda: this type of goldfish is characterized by an ornament on the head that gives it a rounded appearance.
• Ryukin: these organisms have well-developed fins, so they are observed almost in the form of a veil. In addition to this, its back seems to have a kind of "hump" that gives it a peculiar appearance.
• Jikin: These individuals exhibit a forkless tail, which is also known as a peacock tail. This type of goldfish has a white coloration with red spots on some parts of the body, which highlights its scales.
• Fan tail: this variety is characterized by a caudal fin (tail) shaped like a fan, while its other fins have a normal growth. On the other hand, its body appears rounder than that of other varieties, with intense colorations of red, white or orange.

The invasion of Japanese fish

Although beautiful, Japanese fish have a great ability to withstand diverse environments, which transforms them into potential invasive species. In fact, goldfish are already considered a threat to nature, as their accidental or intentional release into other habitats is already an ecological problem.

Remember that this type of fish should not be released for any reason, because, although they can survive in the environment, this causes serious problems for native species. If for some reason you can no longer have your pet with you, try giving it up for adoption to someone who can take care of it. The life of these small animals depends entirely on their owners, so always try to see for their well-being.

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