Ryukin Goldfish

Fancy Goldfish

Family: Cyprinidae Ryukin Goldfish, Fancy Goldfish, Carassius auratusCarassius auratus auratusPhoto © Animal-World: Courtesy David Brough
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We have a reddish/orange Ryukin that was the size of a 10 cent when we got it . Some 4years later , it is a bulging healthy 3 inches long magnificent species now.... (more)  Ray Bullock

The Ryukin Goldfish is a captivating novelty with a very round body shape and pretty colors!

The beautiful Ryukin Goldfish are considered a Japanese version of the Fantail Goldfish. They were developed from the common Fantail Goldfish and like their Fantail counterpart, they are one of the more rounded or egg-shaped fancy gold fish.

The Ryukin Fancy Goldfish differs from the Fantail in that they have an extremely high back, often described as a dorsal hump. It starts in the neck region and gives them a more pointed appearance to the head, They also have a wider caudal fin than the Fantail. A distinguishing feature common to both the Fantail and the Ryukin Goldfish are their split or double caudal (tail) fin.

Red and White Ryukin Goldfish
Red and White Ryukin Goldfish

A long-tailed version of this fish has also been developed and is called the Fringe-tail or Ribbon-tail Ryukin. Colors they come in are red, red and white, tri-color, calico, white, and chocolate.

Both Fantail Goldfish and Ryukin Goldfish are recommended for the beginner, but like all the goldfish with this rounded body shape they can be susceptible to swim bladder problems. Other good beginner fancy goldfish are Common Goldfish, Comet Goldfish, the Shubunkin, and the Black Moor.

These beginner goldfish can tolerate temperatures a few degrees above freezing, as long as the cooling drops only a few degrees a day. Their hardiness and ability to live at colder temperatures makes them ideal for outdoor ponds. The Black Moor is the only possible exception to this, not because it lacks hardiness but because of its telescopic eyes. These eyes cause it to have poor vision so it is not a good competitor for food, and they are subject to injury and infection.

For more goldfish information, see:
Goldfish Care: Fancy Goldfish and Goldfish Diseases

Geographic Distribution
Carassius auratus auratus
Data provided by FishBase.org
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Cypriniformes
  • Family: Cyprinidae
  • Genus: Carassius
  • Species: auratus auratus
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Ryukin Goldfish - Quick Aquarium Care
  • Aquarist Experience Level: Beginner
  • Size of fish - inches: 6.0 inches (15.24 cm)
  • Minimum Tank Size: 10 gal (38 L)
  • Temperament: Semi-aggressive
  • Aquarium Hardiness: Very Hardy
  • Temperature: 65.0 to 72.0° F (18.3 to 22.2° C)
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Habitat: Distribution / Background

The goldfish of today are descendants of a species of wild carp known as the Prussian Carp, Silver Prussian carp, or Gibel Carp Carassius gibelio (syn: Carassius auratus gibelio), which was described by Bloch in 1782. These wild carp originated in Asia; Central Asia (Siberia). They inhabit the slow moving and stagnant waters of rivers, lakes, ponds, and ditches feeding on plants, detritus, small crustaceans, and insects.

For many years, it was believed that goldfish had originated from the Crucian Carp Carassius carassius described by Linnaeus in 1758. This fish has a wide range across the waters of the European continent, running west to east from England to Russia, north to Scandinavian countries in the Arctic Circle and as far south as the central France and the Black Sea. However, recent genetic research points to C. gibelio as a more likely ancestor.

Goldfish were originally developed in China. By the 1500s, goldfish were traded to Japan, arriving in Europe in the 1600s and America in the 1800s. The majority of the fancy goldfish were developed by Asian breeders. We can see the results of this centuries-long endeavor in the wonderful colors and shapes of goldfish today.

Today domesticated goldfish are distributed world-wide. The Ryukin Goldfish is one of the more than 125 captive bred fancy gold fish varieties.

  • Scientific Name: Carassius auratus auratus
  • Social Grouping: Groups - Can be kept singly or in groups.
  • IUCN Red List: NE - Not Evaluated or not listed - There are no wild populations of this captive bred variety.


The Ryukin Goldfish is an egg-shaped variety of goldfish. The body is short and stubby. They have an extremely high back, often described as a dorsal hump, that starts in the neck region giving them a more pointed appearance to the head.

The distinguishing feature common to both the Ryukin Goldfish and the Fantail Goldfish are their split or double caudal (tail) fin. A long-tailed version of the Ryukin has also been developed and is called the Fringe-tail or Ribbon-tail Ryukin. They are available in red, red and white, tri-color, calico, white, and chocolate.

Calico Ryukin Goldfish

Both of these goldfish will generally reach about 6 inches (15 cm), though some hobbyist report their Ryukins reaching up to a whopping 10" (25 cm). The average goldfish lifespan is 10 – 15 years, though living 20 years or more is not uncommon in well maintained goldfish aquariums and ponds.

  • Size of fish - inches: 6.0 inches (15.24 cm) - Average size is 6" (15 cm), but have been reported to reach 10" (25 cm) in an exceedingly well maintained tank or pond.
  • Lifespan: 15 years - The average goldfish lifespan is 10 – 15 years, but they have been known to live 20 years of more when well maintained.

Fish Keeping Difficulty

Ryukin Goldfish are some of the hardier species of goldfish.

Calico Ryukin Goldfish

They are very undemanding of water quality and temperature, and recommended for the beginner. They can do well in goldfish aquariums as well as ponds as long as the environment is safe and their tank mates are not competitive.

Many people will keep goldfish in an aquarium with no heater or filtration. But for the best success in keeping these goldfish, provide them the same filtration, especially biological filtration, that other aquarium residents enjoy.

  • Aquarium Hardiness: Very Hardy
  • Aquarist Experience Level: Beginner

Foods and Feeding

Since they are omnivorous, the Ryukin Goldfish will generally eat all kinds of fresh, frozen, and flake foods.

Tri-color Ryukin Goldfish

To care for your Ryukin goldfish, keep a good balance by giving them a high quality flake food everyday. Feed brine shrimp (either live or frozen), blood worms, Daphnia, or tubifex worms as a treat. It is usually better to feed freeze-dried foods as opposed to live foods to avoid parasites and bacterial infections that could be present in live foods.

  • Diet Type: Omnivore
  • Flake Food: Yes
  • Tablet / Pellet: Yes
  • Live foods (fishes, shrimps, worms): Some of Diet
  • Vegetable Food: Some of Diet
  • Meaty Food: Some of Diet
  • Feeding Frequency: Several feedings per day

Aquarium Care

These goldfish are hardy and easy to keep in a well maintained tank. Minimum tank size is 10 gallons, so make sure water changes are frequent in such as small tank. Regular weekly water changes of 1/4 to 1/3 is strongly recommended to keep these fish healthy. Snails can be added as they reduce the algae in the tank, helping to keep it clean.

  • Water Changes: Weekly - Goldfish produce more waste than most other freshwater fish and benefit greatly from more frequent water changes.

Aquarium Setup

Setting up a goldfish aquarium in a manner that will keep your fish happy and healthy is the first step to success. The shape and size of the aquarium is important and depends upon the number of goldfish you are going to keep. These fish need a lot of oxygen and produce a lot of waste. Good filtration, especially biological filtration, is very helpful in maintaining the water quality of the aquarium. A filtration system will remove much of the detritus, excess foods, and waste, which keeps the tank clean and maintains the general health of the goldfish.

  • Tank parameters to consider when choosing a goldfish aquarium:
    • Tank size
      Ten gallons is the absolute minimum required to house a Ryukin Goldfish. It's best to start with a 20 - 30 gallon tank for your first goldfish and then increase the size of the tank by 10 gallons for each additional goldfish. Providing a large amount of water per fish will help dilute the amount of waste and reduce the number of water changes needed.
    • Tank Shape
      Always provide the maximum amount of surface area. A large surface area minimizes the possibility that the goldfish will suffer from an oxygen shortage. Surface area is determined by the shape of the tank. For example an elongated tank offers more surface area (and oxygen) than a tall tank. Oval or round tanks that are wide in the middle and narrower toward the top might be filled less than full to maximize the surface area.
    • Number of fish
      For juveniles a general rule of thumb is 1 inch of fish (2.54 cm) per 1 gallon of water. However, this rule only applies to young fish. Larger gold fish consume much more oxygen than young fish so maintaining this formula for growing fish will stunt them and could contribute to disease and even death.
    • Fish size and growth
      To allow for proper growth, either buy fewer fish than the maximum number or be prepared to get a larger tank. To prevent stunted growth and other health problems, don't overstock the aquarium.

Goldfish are a cold water fish and will do best at temperatures between 65 - 72° F (18°- 22° C). The Ryukin Goldfish are one of the hardiest varieties of goldfish and can tolerate temperatures a few degrees above freezing, as long as the cooling drops only a few degrees a day. A quick temperature drop can kill them, so if you live in a very cold climate a heater is advisable.

Provide a gravel substrate to help create a natural and comfortable environment for your fish. You can add some decor, but make sure that all ornamentation is smooth with no protruding points or sharp edges. Smooth rocks or driftwood, should be used sparingly if at all. Aquarium plants would be the best choice of aquarium decor for goldfish, but unfortunately these fish are diggers. Consequently live plants may be uprooted. Artificial plants make a good substitute and silk plants are safer than plastic ones.

Most aquariums come with a cover that includes lighting. A cover for the tank is desirable as it reduces evaporation and though they are not prone to jumping, on occasion some gold fish will jump out. Lighting is not essential for goldfish, but does make the aquarium a nice show piece and lighting will help if you have live plants.

Goldfish are freshwater fish, but they have some tolerance for slightly brackish water. The salinity level for C. auratus must be kept low, below 10% with a specific gravity of less than 1.002.

  • Minimum Tank Size: 10 gal (38 L) - Ten gallons is the absolute minimum required to house this fish. It has high oxygen requirements, produces a lot of waste. It will have very stunted growth if it is kept in a smaller aquarium.
  • Suitable for Nano Tank: Sometimes
  • Substrate Type: Any - A medium sized gravel works best.
  • Lighting Needs: Moderate - normal lighting
  • Temperature: 65.0 to 72.0° F (18.3 to 22.2° C)
  • Breeding Temperature: - In the wild, goldfish spawn in the spring when water temperatures reach about 68° F (20° C).
  • Range ph: 6.0-8.0
  • Hardness Range: 5 - 19 dGH
  • Brackish: Sometimes - The salinity for C. auratus must be kept below 10%, a specific gravity of less than 1.002.
  • Water Movement: Moderate
  • Water Region: All - These fish will swim in all areas of the aquarium.

Social Behaviors

Goldfish are very social animals and thrive in a community. Not only are they a great community fish but they are great scavengers as well. It is really not necessary to add other scavengers or other bottom feeders to the aquarium when you have goldfish.

The Ryukin Goldfish, along with the Fantails, are some of the only egg-shaped goldfish that can readily compete for food with the elongated goldfish such as the Common or Shubunkin Goldfish, so can be housed with them. LIke most fancy goldfish, they will thrive in both freshwater and tropical aquariums as long as there are no aggressive or territorial fish in the tank. Some good tank mates for fancy goldfish are the Chinese Blue Bitterling and the Northern Redbelly Dace.

  • Venomous: No
  • Temperament: Semi-aggressive - This fish tends to be more aggressive than other Fancy Goldfish.
  • Compatible with:
    • Same species - conspecifics: Yes
    • Peaceful fish (): Monitor
    • Semi-Aggressive (): Threat
    • Semi-Aggressive (): Threat
    • Shrimps, Crabs, Snails: Safe - not aggressive
    • Plants: Threat - Goldfish will eat many kinds of aquatic plants, and their constant search for food can end up uprooting plants that they don't eat.

Sex: Sexual differences

During the breeding season the male has white prickles, called breeding tubercles, on its gill covers and head. Seen from above a female will have a fatter appearance when she is carrying eggs. It is impossible to sex Goldfish when they are young and not in breeding season, but generally the male is smaller and more slender than the female.

Breeding / Reproduction

Ryukin Goldfish are egg layers that spawn readily in the right conditions. They can be bred in groups as small as five individuals, but they are very social animals and likely to breed in larger groups as well. The only time Goldfish will spawn in the wild is when spring arrives. To spawn them in the aquarium, you will need to mimic the conditions found in nature.

Provide an aquarium that is at least 20 gallons and make sure the fish are healthy and disease free. Some breeders suggest you treat them for parasites. Many breeders will also separate the males and females for a few weeks prior to breeding to help increase their interest in spawning. Introduce the fish into the breeding tank at the same time. The tank will need a lush environment with solid surfaces for the spawning process and for the eggs to adhere to. Bushy, oxygenating plants, such as Anacharis, work well for this, though artificial plants or fibrous spawning mops can also be used.

To induce spawning, the temperature can be slowly dropped to around 60° F (11° C) and then slowly warmed at a rate of 3° F (2° C) per day until they spawn. Spawning generally begins when the temperatures are between 68° and 74° F (20°-23° C). Feeding lots of high protein food such live brine shrimp and worms during this time will also induce spawning. Feed small amounts three times a day, but don't overfeed. Uneaten scraps will sink to the bottom and foul the water. Maintain the breeding tank with partial water changes of up to about 20% per day.

Before spawning, as the temperature increases, the male will chase the female around the aquarium in a non-aggressive way. This can go on for several days, and the fish will intensify in color. During the spawn, the fish will gyrate from side to side, and the male will push the female against the plants. This stimulates the female to drop tiny eggs which the male will then fertilize. The eggs will adhere by sticky threads to the plants or spawn mop. Spawning can last two or three hours and can produce up to 10,000 eggs.

At this point the parents will start to eat as many eggs as they can find. For this reason, it is best to remove the parents after spawning is complete. The fertilized eggs will hatch in 4 to 7 days, depending on the temperature. You can feed the newly hatched goldfish specialty fry foods until they become big enough to eat flake or brine shrimp, or you can offer the same food as you feed the parents as long as it is crushed very small. At first, the fry are a dark brown or black color in order to better hide and not be eaten by larger fish. They gain their adult color after several months and can be put in with larger fish once they reach about 1 inch long. See Breeding Freshwater Fish - Goldfish for more information on breeding Goldfish.

  • Ease of Breeding: Moderate

Fish Diseases

In properly maintained goldfish aquariums or ponds, goldfish illness is largely preventable. Even so, goldfish illnesses can occur, and if left untreated, may prove fatal. Goldfish are hardy, though, and if treated in a timely manner, most will make a full recovery.

When treating individuals, it is usually best to move the afflicted fish into a separate tank with no gravel or plants and do regular partial water changes. However, if the disease is apparent throughout the main tank, it may be best to do the treatments there. Whether treating in a hospital tank or your main tank, read and follow the manufacturer's instructions for any medication. Some medications can adversely affect the water quality by destroying beneficial bacteria. You may also need to remove the carbon from the filtration system, as carbon will absorb many medications, making the treatment ineffective.

Goldfish diseases are mostly the same as those that afflict other freshwater fish, and the symptoms and treatment of goldfish are also similar. The main types of fish diseases include bacterial infections, fungal infections, parasites, and protozoa. There are also other ailments caused by injury, poor nutrition, or bad water conditions.

One of the more common problems is Ich, which is a protozoan disease. Ich is easy to identify because your fish looks like it is sprinkled with salt. Though Ich is easily treated, like other protozoan diseases, it can be fatal if not caught quickly. Some other protozoan diseases are Costia, which causes a cloudiness of the skin, and Chilodonella, which will cause a blue-white cloudiness on the skin.

External parasites are fairly common, too, but pretty easy to treat and usually not fatal when treated. These include flukes, which are flatworms about 1 mm long with hooks around their mouths. They infest the gills or body of the fish. Another type of parasite is fish lice (Argulus), flattened, mite-like crustaceans about 5 mm long that attach themselves to the body of the goldfish. Lastly, anchor worms look like threads coming out of the fish.

Some bacterial infections include Dropsy, an infection in the kidneys that can be fatal if not treated quickly. Fish Tuberculosis is indicated by the fish becoming emaciated (having a hollow belly). For this illness, there is no absolute treatment, and it can be fatal. Tail/Fin Rot may also be bacterial, though the reduced tail or fins can be caused by a number of factors as well. There is also fungus, a fungal infection, and Black Spot or Black Ich, which is a parasitic infection.

SSwim Bladder Disease is an ailment indicated by fish swimming in abnormal patterns and having difficulty maintaining their balance. This can be caused by a number of things: constipation, poor nutrition, a physical deformity, or a parasitic infection. Feeding frozen peas (defrosted) has been noted to help alleviate the symptoms and correct the problem in some cases.

Other miscellaneous ailments include Cloudy Eye, which can be caused by a variety of things ranging from poor nutrition, bad water quality, and rough handling. It can also be the result of other illnesses, such as bacterial infections. Constipation is indicated by a loss of appetite and swelling of the body, and the cause is almost always diet. Then there are wounds and ulcers. Wounds can become infected, creating ulcers. Wounds can develop either bacterial or fungal infections, or both, and must be treated. There are treatments for each of these diseases individually and treatments that handle both. For more in-depth information about goldfish diseases and illnesses, see Goldfish Care; Fancy Goldfish and Goldfish Diseases.


The Ryukin Goldfish are readily available in fish stores and on-line, but cost more than other fancy goldfish. They come in red, red and white, calico, tri-color, white, and chocolate, with the red and white variety being the least expensive.  The long-tail varieties are more rare..


Author: David Brough CFS
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Lastest Animal Stories on Ryukin Goldfish

Ray Bullock - 2015-07-29
We have a reddish/orange Ryukin that was the size of a 10 cent when we got it . Some 4years later , it is a bulging healthy 3 inches long magnificent species now. Just loves feeding time . Hope it lives a long long life.

Howard - 2010-06-21
We would like to breed our ryukin goldfish. We were wondering how to sex them, also how to measure size, as I've read they need to be 3-4 inches to be mature enough to breed ( including tail or not) We so enjoy and love our calico fantail ryukin. How can I find out if there are any goldfish shows. Hoping to hear from you soon. Thank you for your anticipated help.

  • Heath - 2011-09-19
    Yeah good luck sexing them. I asked and they told me the only way to tell really is when its time the male will get these very small white dots on its gills said its almost too hard to notice. I am still trying to sex my two 2 yr olds Goldy and Nemo
  • Emily Hair - 2012-06-10
    Male goldfish have little tubes sticking up above their nose
  • Jeremy Roche - 2012-10-26

    During the breeding season the male has white prickles, called breeding tubercles, on its gill covers and head. Seen from above a female will have a fatter appearance when she is carrying eggs. It is impossible to sex Goldfish when they are young and not in breeding season, but generally the male is smaller and more slender than the female.

  • Watha - 2015-04-03
    Go to Solidgoldfish.com. Jennie is a wealth of information when it comes to goldfish, including the breeding process. She has numerous tutorials on youtube. Solid Gold
Anonymous - 2013-02-28
My Ryukin is about 1/2 now. And just rating today he can't keep swimming or up in the tank. He tries to stay level but he sinks to the bottom and lays upside down. Can someone help me with what's wrong with him? ): Please and thank you!

  • karen - 2013-03-14
    Swim bladder is a common problem with the ryukin goldfish. Jungle used to make a pond fungus eliminator that was great for this issue. Unfortunately, Jungle products discontinued this product (which came with alot of upset from breeders and hobbyists). frozen peas that have been thawed and fed to the goldfish seems to help some.
  • Kathryn - 2013-09-15
    Try feeding him shelled green peas. Works best if you thaw frozen ones. Do this for at least one day, or until he starts swimming right side up.
  • Sylvia Villa - 2014-03-25
    I own 2, a calico which is over 6 inches, the other a red about 4 inches. I always notice that the calico always starts acting strange and sluggish when the filters need a good rinse. After I clean the filters it's back to normal. The other day I thought I was losing him, he was just staying towards the bottom and not swimming straight. The other fish was getting underneath him and holding him up because he could not swim right or stay up. I quickly cleaned another tank that I have and got it ready for him. I put both in there not wanting to separate them. He has been fine ever since. I think the water he was in was the culprit. It looked clean in the tank but wasn't. I was so scared to lose him, I've had them for about a year now. The smaller one never has these problems. Now I am making sure the water is kept really clean. Hope my experience helps you. It's worth a try.
Linda W. - 2005-05-23
I just bought 2 Ryukin Goldfish--calicos. They are so pretty!! I have them in a 2.5g tank along with a yellow mystery snail and a "sucker" fish. They all seem very happy! I hope I have better luck with these than I did with my others. These are very colorful and very fat! I didn't know what they were until I saw this page. The fish in the picture looks just like my fish!! Wish me luck!

  • Steve - 2013-09-09
    If you don't have better luck with your fish, it is because one calico ryukin goldfish needs 20 gallons to prosper and can live up to ten years.. and then add 10 gallons for each one after that... two would need a minum of a 30 gallon tank.