Calico Telescope Moor Goldfish (Carassius auratus)

Choose a calico telescope goldfish with a one-off pattern

The Calico Telescope Moor is a calico telescope goldfish: a fancy Carassius auratus with protruding eyes, a short, rounded body and a divided twin tail, painted in a patchwork of blue-grey, orange, white and black. No two calicos carry the same pattern, so each fish is a one-off.

Telescope-eyed goldfish are known as dragon eyes in the Far East, where the Bristol Aquarists’ Society reports that they first appeared around 1592. The protruding eye is inherited as a recessive trait, which a 2025 study linked to the LRP2 gene. Calico is one of the two colour groups that the UK globe eye (telescope) standard accepts, alongside metallic black, so this colour form has a recognised place in British shows. The trade name “moor” is the only loose fit: the UK Moor standard is for black fish alone.

Read the calico colours

The society also notes that Chinese calico telescopes differ from the British ideal, which calls for a taller dorsal fin and longer, more pointed paired and anal fins. Pet-quality fish are not bred to a show standard, so fin length and shape vary from fish to fish.

See how calico scales differ

Goldfish colour depends not only on pigment but on what lies beneath each transparent scale. The Bristol Aquarists’ Society describes three scale types, and calico is defined by its mixture of them.

A calico has mostly matt scales, some nacreous scales and only a few reflective ones. That is why its colours look softer than those of a shiny metallic goldfish, and why the blue tones show through at all. If you prefer bold, solid colour, compare our Red and Black Telescope Moor.

Expect a pattern that is still maturing

The society explains that most goldfish start life dark and change as they lose black pigment cells, while some types keep theirs into adulthood. It also notes that light is the most important outside influence on colour: dim surroundings give a washed-out fish, and good lighting gives saturated colour. Diet has a smaller effect. On a young calico the balance of orange, blue and black can still change as it grows, so we cannot promise that the pattern will stay as it is on arrival.

Check what your order includes

One purchase is one live Calico Telescope Moor of about 4–5 cm. At that size the fish is young: the UK standard sets a minimum body length of 5.5 cm before a telescope is judged, and the eyes, body and tail are still filling out. Sex is not specified. OATA notes that adult males show small white tubercles on the gill covers and pectoral fins in spring and summer, and females have deeper bodies, but these signs appear with maturity.

The images on this page show the calico telescope colour form and are based on a reference picture. They do not show the fish you will receive, which will have its own unique pattern.

Plan a group from single purchases

Each unit you add to the basket is one more fish. Before ordering several, total up the space that the adults will need using our stocking calculator, and remember any fish already living in the tank.

Plan space for the adult fish

A telescope sold at 4–5 cm grows to about 20 cm. That is OATA’s figure for fancy goldfish, and Practical Fishkeeping gives the same body length for telescopes, before the fins are counted. The published space guidance differs, so it is worth seeing the figures side by side.

Compare the published minimums

For two adults, OATA’s rule gives 150 litres, against the RSPCA’s 120 litres. Plan for the higher number, and choose a long, wide tank over a tall one: Practical Fishkeeping says depth matters little, and the RSPCA notes that wide tanks exchange oxygen better.

Furnish the tank around the eyes

A calico telescope cannot pull its eyes out of the way. OATA warns against decor with sharp or rough edges, which can damage delicate eyes and fins, and Practical Fishkeeping says the same about sharp ornaments and spiky plants. A plain, open layout also shows off the pattern better than a crowded one.

Run a five-point decor check

1. Substrate: small, round, inert gravel that cannot lodge in the mouth, or aquarium sand.
2. Stones: smooth, water-worn pebbles only; feel every edge with a fingertip.
3. Wood: at most one smooth, water-worn piece with no splinters or points.
4. Plants: tough plants such as Anubias fixed to wood, or soft plastic plants with no pointed tips. OATA notes that goldfish may eat delicate live plants.
5. Lighting and position: overhead lighting for a day and night rhythm, with the tank away from windows, heaters and draughts.

Keep the water clean, cool and steady

OATA’s fancy goldfish values are the ones to follow. FishBase gives the species a pH of 6.0–8.0 and hardness of 5–19 dH, and the RSPCA gives 10–21°C, so all three sources agree on a cool, moderately hard, near-neutral to alkaline water.

Condition tap water in three steps

1. Test your tap water once so you know its pH and hardness, and compare the results on our water matcher.
2. Treat every bucket with a dechlorinator from our water care and treatments range, as OATA and Practical Fishkeeping both advise.
3. Bring the new water to the aquarium temperature before it goes in, as the RSPCA recommends.

Our article on water chemistry explained covers what each reading tells you. A heater is not normally needed; OATA suggests one only for a very cold room.

Run an efficient filter with a soft return

Every goldfish tank needs a filter, OATA says, but fancy goldfish do best in gentle flow, so turn the output down or spread it with a spray bar. Practical Fishkeeping suggests an external filter rated at 1,000 litres per hour or more for telescopes, an airstone for extra oxygen and activated carbon against the smell that goldfish tanks can develop.

Work through the weekly routine in order

1. Test ammonia, nitrite and nitrate (OATA advises weekly testing).
2. Siphon debris from the gravel while you draw off water: 25% a week by OATA’s guidance, or up to 50% if possible, as Practical Fishkeeping suggests.
3. Squeeze out filter media in the removed tank water, never in tap water.
4. Refill with dechlorinated water at tank temperature.
5. Check each fish’s eyes, fins and breathing.

If the aquarium is new, cycle it before the fish arrives. The RSPCA advises fishless cycling for at least two weeks; our guide to cycling a new aquarium sets out the method.

Feed sinking food once a day

OATA recommends a goldfish-specific flake, granule or pellet, because goldfish need more carbohydrate than many other fish, and asks keepers to feed only what is eaten within a few minutes, once a day. Practical Fishkeeping suggests sinking goldfish pellets for telescopes, so the food comes to rest where a slow fish can find it. For variety, OATA lists daphnia, bloodworm, brine shrimp, aquatic plants, blanched lettuce and thawed, shelled peas.

Plan a simple feeding rotation

If the fish gulps air and floats or tilts after a meal, OATA suggests switching to a different or slow-sinking food. Our article on swimming sideways explains other causes to rule out.

Bring it home gently

OATA asks you to check that ammonia and nitrite read zero before adding fish, to add fish a few at a time so the filter is not overwhelmed, and to keep a close eye on newcomers for the first week. Avoid buying any fish from a tank where others look unwell.

Follow the first-week plan

For more detail see our guide on how to acclimatise new fish, and read our delivery and Live Arrival Guarantee terms before you order.

Learn the early warning signs

A calico’s mottled colouring can hide small changes, so look closely during your daily check. OATA’s warning signs are: hanging at the surface or sitting on the bottom, colour unusually dark or pale, faster or slower breathing, white spots, fluffy growths, damaged fins or missing scales, clamped fins, rubbing against objects, change in weight and reduced appetite.

Act on what you see

Telescope-eyed goldfish are reported to have thinner retinas than normal-eyed goldfish, according to research summarised in a 2025 study, so protecting the eyes is the most valuable thing you can do.

Keep it with slow twin-tailed fancies

OATA says fancy goldfish can live alone or with other fancy goldfish, but advises against common goldfish, which are faster, take most of the food and sometimes nip fins. The RSPCA gives the same advice about mixing single- and twin-tailed goldfish and says a goldfish can be kept on its own. FishBase suggests groups of five or more, so sources differ; a single calico is fine, and a group simply needs more space.

Screen each companion

Use our tank mates tool to check a planned group, and browse the whole fancy goldfish range or our wider goldfish and coldwater fish collection for companions.

Breed calico telescopes only if you can rear the young

OATA recommends attempting goldfish breeding in a large home aquarium, with two males for each female. Warming the water slowly to about 20°C, often after a partial water change, usually triggers spawning. The eggs stick to plants or a spawning mop, which should go into a separate tank because the parents eat eggs and fry; they usually hatch in about three days. Telescope eyes are recessive, so young only show them when both parents pass the trait on. Rearing fry needs a dedicated set-up and specialist fry food, and you will need homes for the young.

Answer calico telescope goldfish questions

What is a calico telescope goldfish?

A fancy goldfish, Carassius auratus, with protruding telescope eyes, a short rounded body and a divided double tail, coloured calico: a bluish background with patches of orange, red, white and other colours, spotted with black. It is sold in the trade as a Calico Telescope Moor.

What does calico mean in goldfish?

Calico describes a mix of colours and scale types. The Bristol Aquarists’ Society explains that calico fish have mostly matt (non-reflective) scales, some nacreous (pearly) scales and only a few metallic ones, which gives the soft, mottled look.

Is a calico telescope a recognised variety in the UK?

Yes. The UK globe eye (telescope) standard accepts calico as well as metallic black. The trade name “moor” is the only part that does not fit, because the UK Moor standard is black only.

Will my calico telescope look like the photo?

No two calicos are alike. The pictures show the colour form, not your fish, and the pattern on a young fish can still develop as it grows. Good lighting brings out the colours most strongly.

How big does a calico telescope get?

About 20 cm, according to OATA’s figure for fancy goldfish and Practical Fishkeeping’s figure for telescope body length, not counting the fins. You receive a young fish of about 4–5 cm.

How many litres does it need?

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

What temperature does it need?

Unheated room temperature in most homes. OATA gives 4–25°C with 15–23°C as the best range; the RSPCA gives 10–21°C. A heater is only needed in a very cold room.

Can it share a tank with comets or common goldfish?

No. OATA and the RSPCA both advise keeping slow twin-tailed goldfish apart from fast single-tailed ones, which take the food and may nip fins. Choose other telescopes, moors, fantails, ryukins or orandas instead.

Can I keep a calico telescope outdoors?

We advise an indoor aquarium. OATA says fancy goldfish are best kept indoors, and the exposed eyes are at risk from rough pond edges and fast pond fish.

Consult the care references

• Bristol Aquarists’ Society: Globe eye goldfish — telescope eye history and names, the UK colour groups (calico and black) and Chinese calico type
• Bristol Aquarists’ Society: Goldfish information — metallic, nacreous and matt scales, the calico mixture and how light and diet affect colour
• Bristol Aquarists’ Society: Broadtail moor — the UK Moor standard, black only
• OATA: How to look after fancy goldfish — adult size, water values, tank volume, filtration, feeding, acclimatisation, warning signs, compatibility and breeding
• 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 — goldfish kept alone and single- versus twin-tailed varieties
• FishBase: Carassius auratus — family, species water values and aquarium notes
• Li et al. 2025, International Journal of Molecular Sciences — recessive inheritance of telescope eyes, the LRP2 gene and retinal thickness
• Tropical Fish Co delivery policy — current dispatch and Live Arrival Guarantee terms.