Red Telescope Moor Goldfish (Carassius auratus)

Choose a solid red telescope goldfish

The Red Telescope Moor is a red telescope goldfish: a fancy Carassius auratus with eyes that bulge out from the sides of the head, a short, rounded body and a divided double tail, coloured metallic red from nose to fin tips. Practical Fishkeeping describes telescopes as essentially fantails with protruding eyes, and their care does not change with colour.

Telescope-eyed goldfish have a long history. The Bristol Aquarists’ Society records that they are known as dragon eyes in the Far East, where they reportedly first appeared around 1592, and as telescope eyes in the USA. A 2025 study linked the protruding eye to changes in the LRP2 gene and confirmed that it is recessive to the normal eye.

Tell a telescope from a show Moor

In the UK, a metallic telescope-eyed fish shown under the globe eye standard must be black, and the Moor standard is black only. The society notes, though, that self-coloured metallic telescopes are popular elsewhere and increasingly seen in the UK. So this fish is a pet colour form sold under the familiar trade name. Compare it with our classic Black Moor and the patterned Red and Black Telescope Moor, or browse every variety in our cold water oranda and fancy goldfish category.

Understand exactly what arrives

Each purchase is one live Red Telescope Moor of about 4–5 cm. It is a young fish, well short of the 5.5 cm minimum body length that UK telescope standards set before a fish is judged, so its body depth, eyes and tail are still developing. The sex is not specified. If you would like a group, order each fish separately and size the aquarium for all of them as adults.

The photographs are representative images of the colour form, based on a reference picture; they are not photographs of the fish you will receive. Eye size, body shape and the shade of red vary from fish to fish.

Allow for colour that is still settling

The Bristol Aquarists’ Society explains that most goldfish start life black or grey and change to their adult colours as they lose black pigment cells. A young red fish can therefore still carry some darker edges on the fins or scales that fade over time. Red goldfish are rich in red pigment cells, and their metallic shine comes from a reflective layer under transparent scales. Light is the most important outside influence on colour: a fish kept dim looks pale, while good light gives a deep red. Colour-enhancing foods exist, but their effect varies.

Size the tank for the fish it becomes

A telescope that fits in your hand today will not stay small. OATA expects fancy goldfish to grow to about 20 cm, and Practical Fishkeeping gives telescopes about 20 cm of body length before the fins are counted. That is the size to plan around.

The published minimums differ. OATA wants at least 100 litres for one adult and 50 litres more for every additional adult. The RSPCA asks for at least 60 litres per goldfish and rules out bowls and small decorative tanks altogether. Practical Fishkeeping recommends a tank of at least 120 × 60 cm for three adult telescopes. FishBase notes that the species is usually kept in tanks of 100 cm or more. Take the largest figure that applies to your plans.

Measure the footprint before the volume

1. Measure the inside length and width of the tank. Floor area matters more than height for slow, deep-bodied goldfish.
2. Convert to litres with our tank volume tool, remembering that gravel and decor take up part of it.
3. Add up the adults: for example, two adult fancy goldfish need at least 150 litres by OATA’s rule.
4. Check the result against Practical Fishkeeping’s 120 × 60 cm for three adults if you plan a trio.

The RSPCA adds that wide tanks give better oxygen exchange than tall, narrow ones, which suits goldfish well.

Make every surface safe for protruding eyes

The eyes of a telescope goldfish sit out from the head where they meet anything the fish swims past. Practical Fishkeeping warns that sharp decor and plants can damage them, and OATA warns against ornaments with sharp or rough edges for the same reason. Build the aquarium with that single risk in mind.

Choose materials by risk

Practical Fishkeeping adds that the gravel should be small enough to be mouthed without lodging in the fish’s mouth, as goldfish sift through it for food. Use overhead lighting to give a regular day and night, and keep the tank out of direct sunlight and away from radiators and draughts, as OATA advises.

Hold steady coldwater values

A red telescope is a coldwater fish that needs no tropical heating. OATA suggests a heater only if the room gets very cold; the RSPCA notes that a thermostatic heater set at the low end of the range can smooth out swings if you are worried. Aim for steady conditions rather than perfect numbers.

Test your supply water against these values

Treat tap water with a dechlorinator before it goes in, and let it reach room temperature first, as Practical Fishkeeping suggests. Our water matcher tool compares your test results with these values, and the water chemistry care guide explains pH, hardness and the nitrogen readings in plain terms.

Pair a strong filter with gentle flow

OATA calls a filter essential for every goldfish but notes that fancy breeds prefer gentle water movement, so keep the output moderate or spread it with a spray bar. Practical Fishkeeping recommends an external filter rated at 1,000 litres per hour or more for telescopes, plus an airstone, and suggests activated carbon because goldfish tanks can smell. Our article on aquarium filtration explained compares filter types.

Keep a simple maintenance log

New aquariums need time before any fish goes in. The RSPCA recommends fishless cycling for at least two weeks; our nitrogen cycle guide explains the process step by step.

Feed so a slow fish gets its share

Telescopes are slow and deliberate feeders. Practical Fishkeeping recommends sinking goldfish pellets, which settle where a telescope can find them instead of being taken at the surface by quicker fish. OATA advises a food made for goldfish, which need more carbohydrate than many fish, fed once a day in an amount eaten within a few minutes. Extras such as daphnia, bloodworm, brine shrimp, soft plants, blanched lettuce or thawed, shelled peas add variety.

Portion the daily ration

1. Drop in a small pinch of sinking food, such as Tropical Super Goldfish Mini Sticks, where the fish can see it.
2. Watch for a few minutes and add a little more only if it is eaten quickly.
3. On some days, swap part of the meal for a frozen food such as Koi and Goldfish Special frozen food.
4. Siphon out anything left after a few minutes.

If the fish floats tail-up or struggles to stay level after eating, OATA suggests a different or slow-sinking food. Read our article on buoyancy problems for further steps.

Introduce it to a cycled aquarium

Before the fish arrives, OATA asks you to confirm that ammonia and nitrite read zero, and to stock gradually so the filter bacteria can keep pace. Adding too many fish at once can cause what OATA calls new tank syndrome.

Arrival checklist

1. Switch the aquarium lights off.
2. Float the sealed bag on the surface for about 10 minutes so the temperatures meet.
3. Open the bag and add small amounts of aquarium water over up to 20 minutes.
4. Net the fish into the aquarium, leaving the bag water behind, and dispose of it.
5. Watch closely for the first week and test the water more often than usual.

Our guide to acclimatising new fish adds tips for a calm first day, and our delivery information sets out dispatch days and the Live Arrival Guarantee.

Spot trouble early

OATA’s list of warning signs applies to every goldfish: hanging at the surface or resting on the bottom, unusual colour, faster or slower breathing, white spots, fluffy growths, torn fins or lost scales, clamped fins, flicking against objects, weight change and loss of appetite. On a telescope, check the eyes first: they are the most exposed part of the fish.

Match signs to responses

A 2025 study notes that telescope-eyed goldfish are reported to have thinner retinas than normal-eyed fish, so treat any eye injury seriously and prevent it where you can.

Choose companions that move at its pace

A red telescope competes poorly with fast fish. OATA advises keeping fancy goldfish alone or with other fancy goldfish and not with common goldfish, which outcompete them for food and sometimes nip their fins. The RSPCA agrees that single- and twin-tailed goldfish should not be mixed, and adds that a goldfish does not need companions at all. FishBase, in contrast, suggests groups of five or more, so the sources differ: a single telescope is acceptable, and a small group is fine in a tank big enough for every adult.

Run through a compatibility check

Our tank mates checker flags combinations to avoid before you buy, and the fancy goldfish and coldwater fish collection shows the slow-swimming varieties we stock.

Keep telescopes indoors

OATA advises that fancy goldfish are best kept in indoor aquariums only. A garden pond exposes protruding eyes to rough stone edges and leaves a slow fish competing with faster pond goldfish, which OATA and the RSPCA both warn against. Every goldfish is also a non-native species in the UK, and OATA reminds keepers that releasing any aquarium fish into the wild is illegal.

If your other goldfish live outdoors

Keep the telescope as a separate indoor aquarium fish rather than moving it between pond and tank. If you keep pond fish too, our page of cold water fish for sale lists the hardier coldwater species that suit outdoor keeping.

Answer red telescope goldfish questions

What is a red telescope moor?

It is a red telescope goldfish: a fancy form of Carassius auratus with protruding eyes, a short rounded body and a divided double tail, in solid metallic red. “Telescope moor” is the trade name it is sold under.

Why is it called a moor if it is red?

Shops use “moor” for telescope-eyed goldfish of many colours. In the UK show standards a Moor is black only and a metallic telescope-eyed fish shown under the globe eye standard must also be black, so a red fish is a pet colour form rather than a show Moor. Its care is exactly the same.

How big does a red telescope goldfish get?

OATA puts fancy goldfish at about 20 cm at most, and Practical Fishkeeping gives telescopes about 20 cm of body length, not counting the fins. The fish you receive is about 4–5 cm, so plan for the adult.

What size tank does it need?

OATA advises at least 100 litres for one adult fancy goldfish plus 50 litres for each additional adult. The RSPCA gives at least 60 litres per goldfish, and Practical Fishkeeping suggests at least 120 × 60 cm of floor space for three adult telescopes.

Will my red telescope stay red?

Most goldfish start dark and lose their black pigment cells as they mature, so a young red fish can still show some dark edges that fade. Light has the biggest effect on how strong the red looks: fish kept dim look pale. We cannot guarantee how the colour will develop.

Does a telescope goldfish need a heater?

Not normally. OATA gives 4–25°C with 15–23°C as the best range and suggests a heater only in a very cold room; the RSPCA gives 10–21°C for goldfish.

What should I feed it?

A goldfish pellet or granule once a day, giving only what is eaten within a few minutes, with daphnia, bloodworm, brine shrimp or shelled peas as extras. Practical Fishkeeping recommends sinking goldfish pellets for telescopes.

Which fish can live with it?

Other slow twin-tailed fancy goldfish: moors, other telescopes, fantails, ryukins, orandas and broadtails. Do not add common goldfish, comets or shubunkins, which are faster and take the food.

Can a red telescope live in a pond?

We advise against it. OATA says fancy goldfish are best kept in indoor aquariums, and protruding eyes are easily damaged in a pond with rough edges and fast fish.

Consult the care references

• Bristol Aquarists’ Society: Globe eye goldfish — telescope eye names and history, UK colour rules and popularity of self-coloured metallic telescopes
• Bristol Aquarists’ Society: Broadtail moor — the UK Moor standard, black only, and Far Eastern names
• Bristol Aquarists’ Society: Goldfish information — colour development in young goldfish, metallic scales and the effect of light on colour
• OATA: How to look after fancy goldfish — adult size, water values, tank volume, filtration, feeding, acclimatisation, warning signs and compatibility
• Practical Fishkeeping: How do I keep telescope eye goldfish? — adult size, tank footprint, filter, gravel, safe decor, sinking pellets and companions
• RSPCA: Choosing an aquarium for pet fish — space per goldfish, temperature range, wide tanks and fishless cycling
• RSPCA: Keeping pet fish together — keeping goldfish alone and not mixing single- and twin-tailed varieties
• FishBase: Carassius auratus — family, native range, species water values and aquarium notes
• Li et al. 2025, International Journal of Molecular Sciences — the LRP2 gene, recessive inheritance of telescope eyes and retinal thickness
• Tropical Fish Co delivery policy — current dispatch and Live Arrival Guarantee terms.