Telescope Goldfish

Demekin, Dragon Eye Goldfish, Globe Eye Goldfish

Family: Cyprinidae TTelescope Goldfish, Globe Eye Goldfish, Demekin, Dragon Eye GoldfishCalico Telescope GoldfishCarassius auratus auratusPhoto © Animal-World: Courtesy Tammy
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hi, i was brought 2 telescope eye goldfish the other day in a bowl.. i know thats waayyyy too small for them but the guy in the shop said they'd be fine. I'm... (more)  Amy Bannister

The Telescope Goldfish is a bizarre-looking fish, with eyes perched on stalks sticking out from its head!

The eyes are the most curious characteristic of the Telescope Goldfish. Their large eyes are set on top of long telescope or cone-like stalks mounted on the sides of its head. On some individuals, these stalks can extend out as far as 3/4 of an inch (19 - 20 cm), but they don't really start to protrude until these fish are about 6 months old.

The Telescope Goldfish are believed to have been first developed in China in the early 1700s when they were named the Dragon Eye Goldfish or Dragonfish. Later in that century, in Japan, they were given the name Demekin, which the Japanese still call them today.

The Telescope Goldfish is one of the more rounded or egg-shaped fancy goldfish. It is very similar to the Fantail Goldfish except for its telescoping eyes and slightly smaller size. The body is short and stubby with a very wide head and a split caudal (tail) fin that is moderate in length and slightly forked. Today, they are also available with long flowing fins and a couple other tail fin styles: veil tail, broadtail, and butterfly tail.

The Telescope Goldfish is available in many different colors in both metallic and nacreous scale types, but seldom in a matte scale type. These include solids of red, blue, chocolate, or white; tri-colored and calico; and bi-colored versions in red/white and black/white. The bi-colored black/white version is affectionately known as the Panda Telescope Goldfish, and one unique chocolate version has orange pompoms. The well known and very popular Black Moor Goldfish is basically a black version of the Telescope Goldfish, though its eyes don't protrude quite as far.

Like the Black Moor, the Telescope Goldfish can live at colder temperatures, but unlike the Black Moor, the Telescope are not considered good beginner fish. This is not because they lack general hardiness, but because of their extremely telescopic eyes. Their eyes cause them to have poor vision, so they are not a good competitor for food. Their eyes are also subject to injury and infection. These fish will thrive best housed with the other similarly handicapped fish, including the Black Moor and the less hardy Bubble Eye Goldfish, Lionhead Goldfish, and Celestial Goldfish.

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

Geographic Distribution
Carassius auratus auratus
Data provided by
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Actinopterygii
  • Order: Cypriniformes
  • Family: Cyprinidae
  • Genus: Carassius
  • Species: auratus auratus
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Telescope Goldfish - Quick Aquarium Care
  • Aquarist Experience Level: Intermediate
  • Size of fish - inches: 8.0 inches (20.32 cm)
  • Minimum Tank Size: 10 gal (38 L)
  • Temperament: Peaceful
  • Aquarium Hardiness: Moderately 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.

The Telescope Goldfish is also known as the Demekin, Dragon Eye Goldfish, and Globe Eye Goldfish. It is believed to have been developed in China in the early 1700s where it was known as the Dragon Eyes or the Dragonfish. In the later part of the 1700s, it was produced in Japan where it is known as the Demekin. The Black Moor is still referred to as the Dragon Eye Goldfish as well as the Black Demekin. Today, domesticated goldfish are distributed world-wide, and the Telescope Goldfish is one of more than 125 captive-bred fancy goldfish 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 Telescope Goldfish is an egg-shaped variety of goldfish. Other than its telescoping eyes and slightly smaller size, a basic Telescope Goldfish is very similar to the Fantail Goldfish. The body is short and stubby with a very wide head and a split caudal (tail) fin that is moderate in length and slightly forked.

Telescope Goldfish will generally reach up to about 5  inches (12.7 cm), though they have been known to grow much larger in many aquarists' tanks. With optimal conditions, they can reach a length of up to 8 inches (20.32 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.

Their large eyes are set on top of long telescope or cone-like stalks protruding from the sides of the head. On some fish, these stalks can extend out as far as 3/4 of an inch (19 - 20 cm), but they don't really start to stick out until these fish are about 6 months old. Today, the Telescope Goldfish are also available with long flowing fins and a couple other tail fin styles: veil tail, broadtail, and butterfly.

These fish come in many different colors in both metallic and nacreous scale types, but seldom in a matte scale type. These include solids of red, blue, chocolate, or white; tri-colored and calico; and bi-colored fish in red/white and black/white.

The bi-colored black/white version is affectionately known as the Panda Telescope Goldfish, and one a unique chocolate version has orange pompoms. The well known and very popular Black Moor Goldfish is basically a black version of the Telescope Goldfish, though its eyes don't protrude quite as far.

  • Size of fish - inches: 8.0 inches (20.32 cm) - Telescope Goldfish rarely exceed five inches in the home aquarium; however, given optimal conditions, they can grow up to eight inches in length.
  • 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

The Telescope Goldfish are not considered a good beginner fish. This is not because they lack general hardiness, but rather because of their extremely telescopic eyes. Besides causing them to have poor vision, their eyes are subject to injury and infection.

These fish are very undemanding of water quality and temperature. They can do well in a goldfish aquarium or even a pond if the environment is safe, well maintained, and tankmates are not competitive. When it comes to feeding, the Telescope Goldfish will not thrive with fast, competitive tankmates.

Many people will keep goldfish in an aquarium with no heater or filtration, but for the best success, provide them the same filtration, especially biological filtration, that other aquarium residents enjoy. Be careful when netting these fish, as their eyes are easily damaged. 

  • Aquarium Hardiness: Moderately hardy
  • Aquarist Experience Level: Intermediate

Foods and Feeding

Since they are omnivorous, the Telescope Goldfish will generally eat all kinds of fresh, frozen, and flake foods. To keep a good balance give 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. Due to the protruding eyes they have poor vision and a harder time seeing their food, so need extra time to feed.

  • 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 - This fish has poor vision and is a poor swimmer. As such, it might easily be out-competed for food by swift tankmates.

Aquarium Care

These goldfish are hardy and easy to keep in a well-maintained tank as long as the decor has no protruding points that can injure their eyes. Minimum tank size is 10 gallons, but make sure water changes are frequent in such a small tank. Regular weekly water changes of 1/4 to 1/3 are 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 Telescope 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 Telescope Goldfish 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 keep in mind that the eyes of the Telescope Goldfish are a handicap. These fish have very poor vision, so 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 these fish are diggers and may uproot live plants. 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 goldfish will jump out. Lighting is not essential for goldfish, but does make the aquarium a nice showpiece and 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, and produces a lot of waste. It will have very stunted growth if it is kept in a smaller aquarium.
  • Suitable for Nano Tank: Sometimes - A Nano tank is fine as long as it is 10 gallons or more.
  • 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. The Telescope Goldfish, along with the Black Moor Goldfish, Bubble Eye Goldfish, and the Celestial Goldfish, are all visually handicapped. They cannot readily compete for food with other types of goldfish so may not fare well if housed with them, but they will do well housed together. Goldfish are great scavengers, so it is really not necessary to add other scavengers or other bottom feeders to the aquarium when you have goldfish.

  • Venomous: No
  • Temperament: Peaceful
  • Compatible with:
    • Same species - conspecifics: Yes
    • Peaceful fish (): Safe
    • Semi-Aggressive (): Threat
    • Semi-Aggressive (): Threat
    • Shrimps, Crabs, Snails: Safe - not aggressive
    • Plants: Threat - Goldfish will eat many kinds of aquatic plants. In their constant search for food, they 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

Telescope 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.

Swim 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 Telescope Goldfish is inexpensive and readily available in fish stores and online.


Author: David Brough CFS
Lastest Animal Stories on Telescope Goldfish

Amy Bannister - 2014-09-09
hi, i was brought 2 telescope eye goldfish the other day in a bowl.. i know thats waayyyy too small for them but the guy in the shop said they'd be fine. I'm looking to upsize for them but really can't stretch to a 10 or 20 gallon tank at the moment. they are only about an inch ling each. will a 15L or 20L be enough for the time being, with a filter and airstone put into it. also could you suggest the best food for them a few people have said sinking pellets but they don't seem to be finding them very well

Emilly - 2011-09-10
Hi I got my telescopic eyed Goldfish and her name is Bow, last night just before I went to bed I checked on her and she seemed to be resting in the bottom corner? Was she just resting or sleeping or is something wrong with her ..... she seems to be fine when I feed her and then she is fine ..... I hope she is okay?

  • Clarice Brough - 2011-09-12
    Well, if she seems fine most of the time, she probably is fine. But I would keep and eye on her just to be sure. Staying in a corner all the time would indicate something's wrong, like the water quality is bad, or another fish picking on her.
  • Anonymous - 2013-06-26
    I have a similar problem with my little fish, was slim like a shark, now has a big belly, rests in the corner. We have had our horn snail laying eggs and I think little fish has eaten some! I'm really worried about my little fish. Is there anything I can do? I changed the water and two days later he has a big belly and resting on the bottom. It takes little gulps at the surface, but not eaten food!
  • Anonymous - 2013-07-07
    Your little fishy may have swallowed some air when eating food, considering he/she has a big tummy. You should feed your fish frozen peas, not flakes or pellets, which may make the fish's stomach fill with air. Hope I helped! =)
  • Gary - 2013-08-11
    Hi, I have had a few globeyes and 1 has died. My 1st fish 'Horatio' had his problems at the start but he got through them. With regards to your fish resting on the bottom, they do rest from time to time and do sleep for a while, so don't be worried about that. The fish's belly will grow large due to its breed. Make sure the water quality is good and do regular changes with the recommended solutions.
  • Anonymous - 2014-06-03
    Hi, I have the same problem too I think. My goldfish is fine most of the time but when I get home from work it's in the corner. It's not fat or anything though.
  • John - 2014-07-31
    I have the same problem but they don't rest in the corner they rest at the bottom is there something I should be worried about and yes I have 2
Brenda - 2014-07-13
I have two telescope Goldfish & was wondering if I can use well water & what solutions are best??

  • Clarice Brough - 2014-07-22
    The advantage of using your own well water is there won't be any chlorine or chloramine, so it can work well without adding the typical water conditioners. However I would check the hardness range and make sure it's between 5 - 19 dGH. If higher or lower, you may need to adjust it.
ted - 2013-11-09
I have had a telescope eye goldfish for about 9 days now and it seems to have grown a penis, can anybody help me on this? Is this normal? It doesn't seem right.

  • Clarice Brough - 2013-12-10
    Goldfish are susceptible to anchor worms, that may be the problem.
bettybloop - 2011-11-15
I wanted to name our little friend xray because you can see right thru his eye and out the other side. Cool little buddy. bloop bloop bloop... :) hunnys daughter named him col. sanders.? these fish are cool!! We're down to 2 (had 4) that are doing very well. New tank and just's not quite as simple as we thought it would be. Buy tank, add water, add fish. Learning that there's a little more to it than that. Sorry lenny (fish 1) and wigga (fish 2). And RIP Red. (poor little betta..learning curve..oops. and where can we buy a panda telescope? Anybody know? :) bloop bloop bloop...

  • Charlie Roche - 2011-11-17
    X-Ray is a great name.