Cold Water Fish

Telescope Fish

  • Scientific name: Carassius auratus
  • Common Name: Telescope Fish, Ojones Fish, Demekin, Dragon Eye Goldifish
  • Aquarium size: 200 liters
  • Temperament: Calm
  • Temperature:  Between 18º and 22ºC
  • pH: Between 6 and 8
  • Diet: Omnivores
  • Length: Up to 20 cms


The Telescope fish is a variation or mutation of the famous Goldfish , Carassius Auratus , Red fish, Goldfish … come on, the red carp that we see in hundreds of ponds, throughout the world.
The Telescope fish is also known as the Ojones fish, due to the main characteristic of its most striking morphology: its bulging eyes.
As if we were talking about a bad joke, it turns out that they have pretty bad vision , so they are not good competitors for food.
It is believed that this Goldfish mutation has its origin in China (like almost everything that has to do with Carassius Auratus) around 1,700, when they began to be called Dragon Eye Goldfish or Dragonfish, although later they began to be raised in Japan, where they have been given the popular name of Demekin.


In an aquarium, the Telescope fish does not usually exceed 13 centimeters , although in a pond (or a good-size aquarium) and with the right conditions, it can reach about 20 centimeters.
Within the Goldfish, it is one of the most rounded fish, it has a certain egg shape, it is plump and chubby.
His head is the most striking thing, it is very wide and his eyes attract attention, which stand out as if they were two cones.
Interestingly, the eyes do not start to protrude from the head until the fish is about six months old.
So far they would be the common characteristics, because then we can find all kinds of variants of the Telescope fish.There are different colors: blue, chocolate, white, even with mixtures of two or three colors: white and black (Panda Telescope fish), red and white …
Regarding their morphology, there are some with a caudal veil tail, horsetail, butterfly, flow fins, etc.
One of the most appreciated variants, although it is not the most striking is the black option of the Telescope fish, although its eyes are not the ones that stand out the most.

Distribution and habitat

The origin of the goldfish, from which the Telescope fish comes, is in Asia and Central Asia , in stagnant and slow waters of rivers, lakes and ponds.
The Goldfish that we know today have their origin in China, later passing to Japan and finally to Europe and America.

Everything you need to maintain your aquarium

  • Best digital pH meter
  • Best Aquarium Test
  • Best anti-algae
  • Best bacteria for aquarium
  • Best siphoner for aquarium
  • Best Aquarium Water Clarifiers
  • Best reverse osmosis filters for aquarium
  • Best UV lamps for aquariums

Aquarium conditions

Aquariums for Goldfish have a lot to do with the size of the fish. These fish tend to grow quite large, and also have a high life expectancy (10 to 15 years or more), so you can start with a minimum aquarium of 40 liters, although ideally a size of at least 80 liters would be better for a adult specimen and as we have more specimens, about 40 liters for each more specimen.
For example, if we want to have 4 fish, the size of the aquarium should be about 200 liters.
They are cold water fish , but that does not mean that we do not have a certain control over the temperature, which should be between 18ºC and 22ºC, with a pH between 6 and 8.
The Telescope fish, like all Goldfish, produces a greater amount of waste than the rest of the fish, so we must have a good water filtration and the aquarium water must be renewed periodically.
The bottom of the aquarium should be gravel. For decoration, the low visibility of the Telescope fish must be taken into account, it is necessary to avoid elements with edges or protruding points , which could accidentally injure it.
A good idea is to add a good amount of plants, although it is usually recommended that they be artificial, because they are fish that tend to dig into the substrate and would eventually eliminate all natural plants.


They are omnivores, so they admit all kinds of fresh and frozen food and also those dry products specially designed for goldfish.
To maintain good hygiene in the aquarium, parasite attacks and infections, it is recommended to use dry food, instead of live food, leaving it for special occasions, such as breeding.
Due to their low visibility, they need time to find their food and finish their meal.

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Behavior and compatibility

it does not see very well, so you should share space with other similar fish, so you do not have a problem with food.
The fish that the Telescope fish will be perfect with are the Black Moor Goldfish, Bubble Eye Goldfish and the Celestial Goldfish , all with a similar vision problem, and with the that will not enter the competition.

Fish compatible with telescope fish

Compatible fish without restrictions

  • Neon Tetra
  • Snail Apple
  • Ancistrus
  • Monjita Fish
  • Molly fish
  • Danio rerio
  • Female betta
  • Corydoras
  • Tiger Barbel
  • Harlequin fish

Compatible fish without restrictions

  • Otocinclo
  • Botia Clown
  • Gourami Pearl

Restricted Compatible Fish

  • Koi Carp
  • Platy
  • Drunk
  • Killi
  • Kribensis
  • Climb
  • Ramirezi


The Carassius auratus reproduce in freedom, only when spring arrives, if we want to reproduce them in the aquarium, we have to imitate the favorable conditions.

  • To start with the Telescope fish, we need an aquarium that has at least 80 liters.
  • We must provide a suitable environment that facilitates spawning and provides surfaces where fish lay their eggs. For this purpose,  bushy plants are usually used, although they can also be made of plastic.
  • The temperature must be lowered to 11ºC, and then increased by 2ºC per day until reaching 20-23ºC, which is the ideal temperature for spawning.
  • In the diet we will add foods rich in proteins, such as shrimp and worms. They will be fed in small amounts, three times a day.
  • We will change 20% of the water every day.
  • Spawning will begin when the temperature rises. The male will chase the female around the aquarium. This ritual can last several days, in which we will observe how the male’s color intensifies.
  • During spawning, the male will roll from side to side and push the female against the plants , causing the female to release her eggs, which will later be fertilized by the male. Spawning can last between two and three hours.
  • Once spawning has occurred, the adults should be removed as they will eat the eggs.
  • The eggs hatch between 4 and 7 days after being fertilized.
  • Once the fry are born, they must be fed with suitable products, until they reach the appropriate size.


The advice that I can offer you for the breeding and conservation of the Telescope fish, have to do with what is exposed in the article.
They are fish that swim quite badly due to their lack of vision, so we should not mix them with other species, with which they have to compete for food.
Their maintenance is relatively simple, except that they are very dirty and you have to be very careful that the aquarium is clean, to avoid the appearance of any type of disease.
Otherwise, Telescope fish farming is simple and can be very successful.

Telescope fish photos

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