Black Moor Goldfish (Carassius auratus)

Choose the classic black moor goldfish

The Black Moor goldfish is the velvet-black, telescope-eyed classic of the fancy goldfish world. It is a form of Carassius auratus, the same species as the common goldfish, bred for large eyes that bulge from the sides of the head, a short, deep body and a long, divided double tail. OATA’s fancy goldfish care sheet names Black Moors alongside orandas and ryukins as varieties bred for finnage, body shape and colour, and notes that fancy goldfish are more delicate than common goldfish.

Goldfish belong to the carp family, Cyprinidae. Genome research published in 2020 shows that they were domesticated from crucian carp in ancient China and selectively bred for more than 1,000 years, and FishBase gives the species’ native range as East Asia. The Black Moor has no wild population: it exists only because breeders have kept and refined it.

Know the UK standard from the shop moor

The Bristol Aquarists’ Society’s moor notes describe the UK broadtail moor as, in effect, a jet black veiltail with spherical protruding eyes, known in the Far East as the black dragon eye or black peony. The society’s variety list records the moor as uncommon in the UK in its show form, while the Far Eastern type is common. Our moors are pet-quality fish rather than show-graded stock, and the gallery images show the variety, not the individual you will receive.

See the rest of our goldfish and coldwater fish, or browse the fancy goldfish category for the orandas, ryukins and broadtails that share its care.

Pick the size that suits your set-up

One purchase supplies one live Black Moor in the size you select: 3–4 cm, 5–6 cm or 8–10 cm. All three are the same variety and grow towards the same adult size, so the choice is about budget and how developed you would like the fish to be on arrival, not about how much space it will eventually need.

Compare the three sizes

OATA puts fancy goldfish at about 20 cm at most, and Practical Fishkeeping gives about 20 cm of body length for telescope-eyed goldfish, not counting the fins. If you plan a group, choose fish of a similar size so the smaller ones are not outcompeted at feeding time.

Understand how the black colour behaves

The Bristol Aquarists’ Society explains that most goldfish reach their adult colours as black pigment cells are gradually lost, but moors and pandas keep those cells into adulthood. Black fish with many pigment cells close to the skin look matt and velvety; where reflective guanine is also present they look metallic black. The UK moor standard lists bronzing on the belly as the usual fault, so shade varies from fish to fish and we cannot promise that a moor will never show bronze or lighter areas as it grows.

Prepare the aquarium before ordering, and check our delivery and Live Arrival Guarantee terms so you are ready on the day the fish arrives.

Give a 20 cm adult enough water

OATA advises the largest aquarium practical, with at least 100 litres for one adult and 50 litres for each additional adult, or a plan to upgrade as the fish grows. A bigger volume dilutes waste and holds its temperature more steadily, which suits a fish that copes poorly with sudden changes.

Practical Fishkeeping suggests at least 120 × 60 cm of floor space for three adult telescope-eyed goldfish long term, and says depth is not important. The RSPCA uses a different yardstick: 2 litres of water per 0.5 cm of goldfish length and at least 60 litres per goldfish. These figures do not agree exactly, so treat the largest as your target and the smallest as a floor you should never go below.

Size the aquarium for the group you intend

The example dimensions are gross volumes before gravel and decor: 80 × 35 × 40 cm is 112 litres and 100 × 40 × 40 cm is 160 litres. Use the tank volume calculator for your own aquarium and the stocking calculator before adding fish. A goldfish bowl is never suitable; the RSPCA explains that small volumes cannot provide a stable environment.

Light and decorate the tank for a dark, big-eyed fish

Those eyes are easily injured. OATA warns against decor with sharp or rough edges that could damage long fins or delicate eyes, and Practical Fishkeeping advises small, round, inert gravel that the fish can dig into and mouth without it getting stuck, smooth pebbles and perhaps a piece of water-worn wood. Hardy Anubias attached to the wood, or plastic plants that are not spiky, give cover without risk.

A black fish can be hard to see against dark decor; a paler rounded gravel or a light background shows a moor off, although that is a matter of taste rather than a care requirement. OATA notes that goldfish readily eat soft live plants, and that plant pots or caves can provide shelter where live plants are not used. Make every opening wide enough that a fish cannot wedge itself in.

Check the layout for eye hazards

• Run your fingertips over every stone, ornament and piece of wood; anything that catches skin can catch an eye.
• Use rounded gravel or sand only; avoid sharp chippings and crushed rock.
• Remove stiff artificial plants with pointed tips.
• Check that filter intakes, heater guards and clips sit flush and cannot rub the fish.
• Leave a clear swimming lane so the fish does not have to weave through tight gaps.

Use overhead lighting to give a regular day and night, as OATA recommends; the RSPCA suggests eight to ten hours a day for most species, switched off at night. Keep the aquarium away from windows, radiators, draughts and constant vibration.

Hold the water values steady

These are OATA’s values for fancy goldfish. OATA adds that goldfish can adapt to wider ranges of temperature, pH and hardness over time; what harms them is sudden change, so keep conditions steady rather than chasing an exact figure.

The RSPCA’s goldfish range is 10–21°C, narrower than OATA’s. The overlap, 15–21°C, satisfies both. OATA says a heater is only needed if the room is very cold; where one is used, the RSPCA suggests setting it at the lower end of the range to prevent swings rather than to warm the water.

Use your tap water safely

Treat every water change with a tap water conditioner that removes chlorine or chloramine; our water care range has suitable conditioners. UK tap water ranges from soft to very hard depending on where you live, so test your own GH, KH and pH once and keep the result. The water matcher compares those numbers with this fish’s range, and our water chemistry guide explains how pH, hardness and nitrate interact.

Size the filter for waste, not for current

OATA says a filter is always essential and that fancy goldfish prefer a 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, plus an air stone, for three telescopes in a 120 × 60 × 45 cm tank. A strong filter with a spray bar gives the waste-processing capacity of the first without the current that would push a short-bodied moor around.

Mature the filter first. The RSPCA recommends fishless cycling, which takes at least two weeks, and Practical Fishkeeping gives the same advice; our guide to the nitrogen cycle explains what happens during those weeks.

Keep a weekly log

Feed it where it can find the food

OATA recommends a specialised goldfish food, because goldfish need more carbohydrate than many species, fed once a day and only as much as is eaten within a few minutes. Practical Fishkeeping advises sinking pellets for telescope-eyed goldfish. Our Tropical Goldfish Pellet is a sinking pellet suited to fancy varieties, and Tropical Super Goldfish Mini Sticks are sinking sticks made for fancy goldfish.

OATA also lists daphnia, bloodworm, brine shrimp, aquatic plants, blanched lettuce and thawed, shelled peas as supplements. Koi and Goldfish Special frozen food is portioned in blisters, which makes a weekly frozen meal easy to measure. Researchers have found thinner retinas and raised pressure inside the eye in telescope-eyed goldfish (Li et al. 2025); whatever the effect on sight, a moor should never have to race a faster fish for its food.

Portion one daily meal

1. Feed at a regular time each day.
2. Drop a small pinch close to the fish; sinking food lets it feed from the bottom without gulping air.
3. Watch for two or three minutes and stop when it loses interest.
4. Siphon out anything left behind, since uneaten food decays into toxic waste.
5. If the fish floats awkwardly or struggles to stay level after meals, try a different or slower-sinking food, as OATA suggests.

Introduce it calmly to a mature aquarium

Before delivery, confirm that ammonia and nitrite are zero and the temperature is inside the range above. OATA’s floating-bag method avoids temperature shock: switch the lights off, float the sealed bag for 10 minutes, then add small amounts of aquarium water to the bag over up to 20 minutes before releasing the fish and leaving the bag water behind. Our step-by-step guide to acclimatising new fish covers the same process with pictures.

Run through the arrival checklist

• The day before: test the water and finish any changes to decor or equipment.
• On arrival: keep the box closed until the aquarium lights are off.
• First 30 minutes: float, add aquarium water a little at a time, release the fish.
• First two days: feed lightly and watch breathing, swimming and both eyes.
• By day seven: retest ammonia and nitrite, then return to the weekly routine.

Add fish gradually when building a group. OATA warns that stocking too fast causes new tank syndrome, in which the filter bacteria cannot keep up and ammonia and nitrite rise.

Read the warning signs early

A healthy Black Moor has clear, bright eyes, undamaged fins, intact scales, no ulcers or bumps, normal swimming and steady breathing. OATA lists the changes to watch for: hanging at the surface, sitting on the bottom, erratic swimming, a darker or paler colour than normal, faster or slower gill movement, white spots, fluffy growths, lost scales, weight change and reduced appetite.

Match the sign to a first response

If a problem persists after you have checked the water, contact us with your readings, the aquarium volume and the other fish it shares with; that information is far more useful than a photograph alone.

Pair it with other slow fancy goldfish

OATA says fancy goldfish can be kept alone or with other fancy goldfish, but not with common goldfish, which swim faster, outcompete them for food and sometimes nip their fins. The RSPCA agrees that single-tailed and twin-tailed goldfish should not share a tank, because the twin-tails are slower and miss out on food. Practical Fishkeeping notes that ryukins and fantails can be mixed with telescopes.

A Black Moor looks its best beside brighter fancy goldfish such as the Red and Black Oranda, the Blue Oranda or the Red and White Ryukin. Check any other combination with our tank mates tool.

Check tank mates against this list

Remember OATA’s extra 50 litres for each additional adult before you add a companion.

Keep it indoors rather than in the garden pond

OATA advises that fancy goldfish are best kept indoors in aquaria only, and its pond fish care sheet names single-tailed varieties such as the shubunkin, sarasa and red comet as the pond goldfish. A Black Moor’s eyes, short body and long fins make it the wrong fish for a pond, where it would have to compete with fast single-tails.

If you already keep pond fish

• Keep moors and other fancy goldfish in an indoor aquarium, and leave the pond to single-tails; our guide to comet goldfish explains what a pond variety needs.
• For an unheated indoor tank of smaller fish instead of goldfish, compare the options in our guide to cold water fish for sale.
• Never move fish between a pond and an aquarium without matching the temperature first.

OATA is clear that aquarium fish must never be released into the wild: it is illegal and usually fatal for the fish.

Answer Black Moor goldfish questions

What is a Black Moor goldfish?

A black, telescope-eyed fancy goldfish, Carassius auratus, with a short deep body and a long divided double tail. The UK standard describes it as, in effect, a jet black veiltail with spherical protruding eyes.

How big do Black Moor goldfish get?

OATA puts fancy goldfish at about 20 cm at most, and Practical Fishkeeping gives about 20 cm of body length for telescope-eyed goldfish, not counting the fins. All three sizes we sell grow towards that adult size.

Which size should I choose?

Choose 3–4 cm, 5–6 cm or 8–10 cm by budget and by how developed you want the fish to be on arrival. The aquarium must be planned for a 20 cm adult whichever size you pick.

Do Black Moors need a heater?

Usually not. OATA gives 4–25°C, with 15–23°C as the optimum, and says a heater is only needed in a very cold room. The RSPCA gives 10–21°C for goldfish.

Will my Black Moor stay black?

Moors keep their black pigment cells into adulthood, unlike most goldfish, but the UK society lists bronzing on the belly as the usual fault. Shade varies from fish to fish, so we cannot guarantee that a fish will never show bronze or lighter areas.

What tank size does a Black Moor need?

OATA advises at least 100 litres for one adult and 50 litres more for each additional adult. Practical Fishkeeping suggests at least 120 × 60 cm of floor space for three adult telescope-eyed goldfish.

What do Black Moors eat?

A goldfish food once a day, giving only what is eaten within a few minutes. Practical Fishkeeping recommends sinking pellets for telescope-eyed goldfish, with daphnia, bloodworm, brine shrimp and peas as extras.

Can a Black Moor live with other goldfish?

Yes, with other slow fancy goldfish such as orandas, ryukins, fantails and other telescopes. Keep it apart from common goldfish, comets and shubunkins.

Can a Black Moor live in a pond?

OATA advises keeping fancy goldfish indoors in aquaria only. Single-tailed goldfish such as comets and shubunkins are the pond varieties.

Consult the care references

• OATA: How to look after fancy goldfish: UK care sheet naming the Black Moor as a fancy goldfish; source of the water values, aquarium size, gentle flow, feeding, acclimatisation and warning signs.
• Practical Fishkeeping: How do I keep telescope eye goldfish?: size, tank footprint, filter rating, eye-safe substrate and decor, sinking pellets, weekly water changes and suitable fancy tank mates.
• Bristol Aquarists’ Society: Broadtail moor: the UK moor standard, Far Eastern names, Far Eastern versus UK type and the common colour faults.
• Bristol Aquarists’ Society: Fancy goldfish varieties: how common the moor is in the UK, the Far East and the USA.
• Bristol Aquarists’ Society: Goldfish information: how goldfish colours develop and why moors keep their black pigment cells; metallic, nacreous and matt scales.
• OATA: How to look after goldfish in tanks: general goldfish aquarium guidance and the advice not to keep comets with fancy goldfish.
• OATA: How to look after pond fish: the goldfish varieties suited to ponds.
• FishBase: Carassius auratus: family, native range and maximum recorded size and age of the species.
• Chen et al. 2020, PNAS: domestication of goldfish from crucian carp in ancient China.
• Li et al. 2025, International Journal of Molecular Sciences: the LRP2 gene behind telescope eyes and the eye differences found in telescope-eyed fish.
• RSPCA: Choosing an aquarium for pet fish: goldfish space guideline, 10–21°C, fishless cycling, lighting hours and tank position.
• RSPCA: Keeping pet fish together: keeping single-tailed and twin-tailed goldfish apart.