Black Lionhead Ranchu Goldfish (Carassius auratus)

Meet the Black Lionhead Ranchu goldfish

The Black Lionhead Ranchu is a fancy goldfish (Carassius auratus, family Cyprinidae) with no dorsal fin, an egg-shaped body, a short divided tail and a soft, raspberry-textured hood that thickens on the head as the fish matures. This listing is the all-black colour form: a velvety charcoal fish whose hood, fins and body share the same deep shade. It is a domesticated variety rather than a wild fish; FishBase places the species’ native range in East Asia, and every fancy shape seen today was created by breeders.

The Bristol Aquarists’ Society’s goldfish history records gold colouring in the Jin dynasty, goldfish kept in monastery ponds during the Tang dynasty and indoor bowl-keeping by the Ming dynasty, with the first goldfish reaching Japan in 1603. A peer-reviewed review by Ota and Abe dates strong selection for body shape to the Song dynasty, more than a thousand years ago, and lists the ranchu among the dorsal-finless strains.

“Lionhead ranchu” is a trade name that joins two show varieties. The Bristol Aquarists’ Society ranchu standard says the ranchu was developed in China and then further developed in Japan, where it is also called a buffalo-head; the lionhead is the flatter-backed Chinese form. Practical Fishkeeping notes that most ranchu sold in shops come from China, so a fish sold as a black lionhead ranchu usually sits somewhere between the two standards. You may also see it called a black ranchu or a black lionhead.

Tell a ranchu from a lionhead

The angles and depths come from the Bristol standards and from goldfish judge Paul Green in Practical Fishkeeping. At 3–4 cm these differences are only beginning to show, so judge the shape of the back and tail as the fish grows rather than on the day it arrives.

Know what arrives with each order

Each purchase is one live Black Lionhead Ranchu with a body of about 3–4 cm. That is a young fish: the Bristol standards set a minimum show length of 5.5 cm for ranchu and lionheads, and the hood on a fish this size is a low cap rather than a full mane. Sex is not chosen or guaranteed.

The gallery images are representative pictures of the variety, made from a reference photograph, and do not show the individual fish you will receive. Expect the same black colour form and dorsal-less shape, with natural variation in hood texture, tail spread and body depth. You can compare it with every variety in our goldfish and coldwater fish range or browse the oranda and fancy goldfish category.

Expect the colour to keep developing

Black in goldfish comes from pigment cells called melanophores lying close to the skin. The Bristol society explains that fish without reflective guanine under the scales look matt and velvety, while those with it look metallic black. Young goldfish of the wild type gradually lose melanophores as they colour up, whereas moors and pandas keep them into adulthood.

Practical Fishkeeping adds that a ranchu’s colour can change almost completely as it matures and that many goldfish whiten with age. We therefore do not promise that a black ranchu stays solid black for life. Many keep their colour; some develop bronze or orange areas over the years, which is a natural change rather than a sign of illness.

These fish are sold singly, so add as many as your aquarium can hold at adult size. The stocking calculator helps you check that before you order.

Size the aquarium for a 20 cm adult

OATA’s fancy goldfish care sheet gives an adult size of about 20 cm and asks for at least 100 litres for one adult plus 50 litres for each additional adult. The RSPCA suggests at least 60 litres per goldfish and a guideline of 2 litres of water for every 0.5 cm of fish, which works out at 80 litres for a 20 cm adult. The Maidenhead Aquatics database prefers a tank around 1.2 metres long and points out that length and width matter more than height.

Sources disagree on the upper size. Practical Fishkeeping notes that ranchu of 30 cm are not uncommon on the showbench, so the 20 cm figure is a sensible planning size, not a ceiling. Give well-bred fish more space if you can.

Work out the volume for your group

We use the larger figure in each row. Measure the real water volume with the tank volume calculator rather than trusting the label, because gravel and décor take up space.

Shape matters for a dorsal-less fish. The ranchu breeders interviewed by Practical Fishkeeping keep their fish in vats with water around 25 cm deep, and a long, wide aquarium of moderate depth suits it better than a tall column of water. Never use a bowl: the RSPCA calls bowls unsuitable because they are too small, leave no room for an efficient filter, have little surface for oxygen exchange and change temperature quickly.

Keep it indoors in cool, steady water

OATA says fancy goldfish are best kept in indoor aquaria only, and that a heater is usually unnecessary unless the room is very cold. The RSPCA gives 10–21°C for goldfish and suggests a heater set at the lower limit only if you are worried about the room cooling sharply. Both bodies warn against draughts, nearby heat sources and direct sunlight.

One honest exception: the Bristol lionhead breeders raise young lionheads in ponds in the mild south-west of Britain and bring them inside in severe weather. That is a specialist breeding system with fish houses and selected stock, not the way to keep a single 3–4 cm black ranchu. We sell this fish for an indoor aquarium.

Choose the right spot before you fill the tank

• Away from windows, radiators, fires and outside doors, so the temperature does not swing.
• On a level stand rated for the full weight of water, gravel and glass.
• Away from loud speakers, slamming doors and constant foot traffic, which OATA lists as stressors.
• With an overhead light on a timer; the RSPCA suggests 8–10 hours of light a day with darkness at night.

Set the water values

Goldfish adapt to a wide range of water, but the published ranges do not agree exactly. The table shows each source side by side and the steady target we suggest for this ranchu.

Match your UK tap water

Treat every drop of new water with a conditioner that removes chlorine and chloramine, as OATA advises. The RSPCA notes that chlorine also leaves water left standing for 24 hours, but standing does not deal with chloramine, so the conditioner is the safer habit. Our water care range has suitable treatments.

Test your tap water for pH and hardness once, then the aquarium weekly. The water matcher compares your readings with the ranges above, and our water chemistry guide explains what each reading means. Aim for stability rather than chasing a perfect number.

Filter hard, but keep the current gentle

Goldfish are large, messy fish; the Maidenhead database asks for efficient filtration and weekly partial water changes to keep nitrate low, and for good oxygen during warm spells. OATA calls a filter essential but adds that fancy breeds prefer a gentle current, so avoid a powerful outlet or spread the flow with a spray bar.

Current matters more than usual for this fish. Ota and Abe report that ranchu have 19–23 vertebrae compared with 25–29 in the ryukin, matching its short, compact build, and Practical Fishkeeping describes traditional Chinese ranchu as often ungraceful swimmers. Choose a filter rated well above the tank volume and diffuse its return.

Mature the filter before the fish arrives. The RSPCA explains that bacteria turn ammonia into nitrite and then into less harmful nitrate, and recommends fishless cycling for at least two weeks, testing every other day, until ammonia and nitrite have risen and fallen back to zero. Our nitrogen cycle guide and filtration guide walk through both steps.

Follow a weekly routine

1. Test ammonia, nitrite and nitrate before you touch anything.
2. Change 25% of the water, as OATA advises; the RSPCA suggests 30%, and either works when readings stay good.
3. Siphon droppings and food from the gravel while you drain.
4. Add conditioned water at the same temperature as the tank.
5. Rinse filter sponges in the removed tank water, never under the tap.
6. Check that the outlet still runs gently and the intake is clear.

Practical Fishkeeping describes ranchu breeders changing all the water every 6–7 days in unfiltered vats, though the magazine itself recommends filtering. That system relies on understocking and daily attention; in a home aquarium with a mature filter, regular partial changes are the safer choice.

Furnish the tank with smooth, safe décor

OATA recommends aquarium gravel or sand and warns against sharp or rough décor that could damage long fins or delicate eyes. A ranchu’s hood is soft living tissue, so the same caution applies to its head. Choose rounded gravel or smooth sand, smooth wood and rounded stones, and leave out rough rock, sharp slate edges and ornaments with narrow holes a growing hood could catch in.

Live plants are welcome, but OATA warns that goldfish may eat them. Tough-leaved plants fixed to wood or stone last longer than soft stem plants, and artificial plants or smooth pots can provide shelter when live plants do not survive.

Lay out the space by function

Feed small, sinking, high-fibre meals

OATA recommends a good flake, granule or pellet made for goldfish, because they need more carbohydrate than many fish, supplemented with daphnia, bloodworm, brine shrimp, blanched lettuce or thawed, shelled peas. Feed once a day and give only what the fish finish within a few minutes. The Maidenhead database stresses a high-fibre diet with sinking pellets or sticks, because goldfish swallow air while feeding at the surface and this is linked to buoyancy problems.

Ranchu breeders interviewed by Practical Fishkeeping feed twice a day, and up to six times a day for young or show fish, but they change all the water weekly. In a home aquarium, follow OATA’s once-a-day guide, or split the same daily amount into two small meals.

Build one measured meal

• Start with a sinking staple such as sinking goldfish mini sticks or a small goldfish pellet.
• Add variety two or three times a week with frozen daphnia or a frozen koi and goldfish mix, thawed first.
• Watch the fish eat and stop when interest fades.
• Remove leftovers within a few minutes so they do not foul the water.

If the fish floats tail-up or struggles to stay level after meals, OATA suggests trying a different or slow-sinking food. Our guide to fish swimming sideways explains how to separate a feeding problem from a water problem.

Settle it in during the first week

Before the fish arrives, confirm that ammonia and nitrite read zero and that the water sits within the target range. Then follow OATA’s floating-bag method: switch the aquarium lights off, float the sealed bag for about 10 minutes to match temperature, add small amounts of tank water to the bag over up to 20 minutes, and release the fish. Our acclimatisation guide shows each step, and our delivery and Live Arrival Guarantee page explains what to do if anything is wrong on arrival.

Use a first-week checklist

Choose tank mates that swim at its pace

OATA says fancy goldfish can live alone or with other fancy goldfish, while the Maidenhead database calls the ranchu sociable and suggests a group of its own kind or other fancies. Most keepers choose two or more, with the tank sized for every adult. OATA advises against common goldfish with fancy varieties, because they swim faster, out-compete fancies for food and sometimes nip their fins.

Screen every companion

Faster twin-tails such as the Red and White Ryukin can share a large tank with a ranchu, but watch feeding time closely so the slower fish still gets its share. The Red and Black Oranda and Blue Oranda are calmer choices. Our comet goldfish guide explains why single-tailed goldfish belong in a separate tank or pond, and the tank mates tool checks any other pairing.

Watch its health and act early

OATA describes a healthy fancy goldfish as having clear, bright eyes, undamaged fins, intact scales, no ulcers or lumps, normal swimming and steady breathing. Check your ranchu at feeding time in good light; on a black fish, small marks and white spots are easier to see from the side than from above.

Pair each sign with an action

The Bristol lionhead breeders name gill flukes as a recurring problem and control them with lower stocking and regular water changes. Bronze patches appearing on an otherwise healthy, eating black fish are usually colour change, not disease. If signs continue after you have corrected the water, contact us with your readings, tank size and a description of what has changed.

Breed lionhead ranchu with realistic expectations

OATA says fancy goldfish spawn most readily in large tanks with about two males to each female, often after a slow rise to around 20°C and a partial water change. Eggs hatch in about three days, and the adults will eat both eggs and fry, so one or the other must be moved. In the breeding season males show white tubercles on the gill covers and pectoral fins, and females are deeper in the body. Practical Fishkeeping’s ranchu breeders also spawn their fish at 20°C.

Few youngsters match their parents. The Bristol lionhead breeders keep about 50 of every 1,000 fry and expect about five to reach show standard, and they find the divided tail and the clean back with no trace of a dorsal fin the hardest traits to hold. A 2020 genome study by Kon and colleagues of 27 goldfish strains located genetic regions linked to dorsal fin loss, which helps explain why careful selection is needed to keep the trait.

Answer Black Lionhead Ranchu buying questions

What is a Black Lionhead Ranchu?

It is a fancy goldfish, Carassius auratus, bred without a dorsal fin and with a soft hood that grows on the head with age. This one is the black colour form. “Lionhead ranchu” is a trade name that joins the Chinese lionhead and the Japanese ranchu, two show varieties that differ mainly in the curve of the back and the angle of the tail.

How big will it get?

Plan for about 20 cm, the adult size OATA and the Maidenhead Aquatics database give for fancy goldfish. Practical Fishkeeping notes that well-grown ranchu of 30 cm are not uncommon on the showbench, so give more room if you can.

What size aquarium does one need?

OATA advises at least 100 litres for one adult fancy goldfish and 50 litres more for each extra adult; the RSPCA gives at least 60 litres per goldfish. A long, wide tank of moderate depth suits a dorsal-less fish better than a tall one.

Will it stay black?

We cannot promise that. Black colour in goldfish comes from pigment cells near the skin, and Practical Fishkeeping notes that a ranchu’s colour can change almost completely as it matures. Some black fish keep their colour for life and some develop bronze or orange areas.

Does it need a heater?

Usually not. OATA says a heater is only needed in a very cold room, and the RSPCA gives 10–21°C for goldfish. Keep it indoors, away from radiators, windows and draughts, and aim for a steady 15–21°C.

Can it go in a garden pond?

We sell it as an indoor aquarium fish. OATA says fancy goldfish are best kept in indoor aquaria only. A slow, dorsal-less fish loses out to faster pond fish and is exposed to cold, predators and rough surfaces outside.

Which fish can live with it?

Other slow fancy goldfish such as lionheads, ranchu, orandas and pearlscales. Avoid common goldfish, comets and shubunkins, which OATA warns swim faster, take the food and sometimes nip fins, and avoid tropical fish that need heated water.

How many fish come with one purchase?

One live Black Lionhead Ranchu at 3–4 cm. Sex is not chosen or guaranteed, and the hood is only starting to form at this size.

Read the care references

• OATA: How to look after fancy goldfish — UK trade guidance on fancy goldfish water values, tank size, flow, décor, feeding, acclimatisation, warning signs, companions and breeding.
• RSPCA: Aquarium environment for fish — welfare guidance on goldfish space, temperature, the nitrogen cycle, fishless cycling, lighting, water changes and why bowls are unsuitable.
• FishBase: Carassius auratus — accepted identity, family, native range, environmental ranges, maximum recorded length and age of the species.
• Bristol Aquarists’ Society: Ranchu — the ranchu show standard: origin, body depth, missing dorsal fin, hood, tail, colours, minimum size and how it differs from the lionhead.
• Bristol Aquarists’ Society: Lionhead — the lionhead standard and breeders’ notes: flat back, hood, colours, lifespan, gill flukes and how few fry reach show quality.
• Bristol Aquarists’ Society: Goldfish information — goldfish history from the Jin to the Ming dynasty, scale types, and how black pigment and guanine create colour.
• Practical Fishkeeping: What’s the difference between a Ranchu and a Lionhead? — Paul Green on the back, tail angle and head growth that separate the Chinese lionhead from the Japanese ranchu.
• Practical Fishkeeping: Ranchu, king of goldfish — how ranchu are bred, kept, fed, judged and how their colour changes with age.
• Maidenhead Aquatics fish database (fishkeeper.co.uk): Ranchu — aquarium values, tank length, diet, buoyancy and lifespan notes for the ranchu.
• Ota & Abe (2016): Goldfish morphology as a model for evolutionary developmental biology — peer-reviewed review of goldfish breeding history and the anatomy of dorsal-less, bubble-eyed and pearl-scaled strains.
• Kon et al. (2020): The genetic basis of morphological diversity in domesticated goldfish — peer-reviewed genome study of 27 goldfish strains locating the genetic regions linked to dorsal fin loss and other traits.
• Tropical Fish Co delivery policy — current dispatch days and Live Arrival Guarantee terms.