Fantail Goldfish, Assorted Colours (Carassius auratus)

Choose a hardy twin-tailed fancy goldfish

The fantail goldfish is one of the oldest and sturdiest of the twin-tailed fancy goldfish. It has a short, rounded body, a smooth outline from nose to dorsal fin and a divided, forked tail that is held high and opens like a fan when you look down on it. If you want your first fancy goldfish, or a calm, colourful fish for a coldwater aquarium, the fantail goldfish is a sensible place to start. This listing is for assorted fantails: the colour is not chosen, so each fish is a small surprise.

Every fantail is Carassius auratus, the same species as the common goldfish. OATA explains that fancy goldfish are varieties produced by selective breeding for finnage, body shape and colour, and that they are more delicate than common goldfish and need greater care. Practical Fishkeeping notes that goldfish were domesticated from a dark greyish-brown wild carp native to Asia and first bred for colour in China more than 1,000 years ago, and FishBase places the wild species in East Asia, China and Japan.

The Bristol Aquarists’ Society (BAS), whose goldfish standards are widely used by UK breeders, calls the fantail relatively easy to breed among the twin-tails and points out that fairly good fantails, unlike most other twin-tailed types, can be bought from many shops at a reasonable price. That is exactly why it suits a first fancy goldfish aquarium.

Know the fantail from its relatives

Compare it with the hooded Red Oranda Goldfish or browse our full oranda and fancy goldfish category to see how the twin-tailed varieties differ.

Select the size and number of fish

One purchase supplies one live fantail goldfish at the size you select: 3–4 cm, 5–6 cm or 8–10 cm. The price is for one fish. All three sizes are young fish of the same variety; the larger sizes simply give you a fish that is further on in its growth and finnage.

The size you select is the size supplied, not the adult size. OATA says fancy goldfish are unlikely to grow larger than 20 cm, so plan every fantail as a fish of up to 20 cm, whichever size you buy.

Because this is an assorted listing, we do not choose the colour. BAS lists the colours a fantail may show: metallic fish can be self-coloured (red, orange, yellow, blue, brown or black) or variegated in a mix of those colours and white, and calico fish have a blue background with patches of violet, red, orange, yellow, brown and white, spotted with black. The photographs show an orange-and-white example of the variety, not the fish you will receive.

Sex is not chosen or guaranteed. OATA explains that fancy goldfish can be sexed only in the breeding season in spring and summer, when males develop small white tubercles on their gill covers and pectoral fins and females look deeper-bodied.

Plan the group before you order

• One fantail: the RSPCA says goldfish do not need the company of other fish and can be kept on their own. Plan at least 100 litres for one adult.
• Two or three fantails: a popular choice; plan about 150 or 200 litres respectively under the OATA guide.
• A larger group: FishBase notes goldfish in aquariums in groups of five or more. Five adults would need about 300 litres under the OATA guide.

The sources do not agree on whether goldfish need company, so let your aquarium size decide the number. Before ordering, read our delivery and Live Arrival Guarantee information so the aquarium is ready on the day the fish arrive.

Plan the aquarium around a 20 cm adult

Goldfish are large, hungry fish that produce a lot of waste, so space is the single most important decision. OATA advises at least 100 litres for one adult goldfish, plus 50 litres for each additional adult, and adds that the larger the aquarium, the more stable its temperature and water quality. The RSPCA gives a different rule of thumb, 2 litres of water for every 0.5 cm of goldfish length, which works out at 80 litres for a 20 cm fish. FishBase records a minimum aquarium length of 100 cm for goldfish. We use the most generous of these figures, the OATA one.

Shape matters as much as volume. The RSPCA explains that oxygen enters the water at the surface, so a wide tank with a large surface is better than a tall one of the same volume. A fantail is a slow, deep-bodied swimmer and appreciates open water along the front of the aquarium.

Run a three-step space check

1. Measure the inside length, width and water depth and work out the real water volume with our tank volume calculator. Gravel and ornaments take up space, so the true volume is lower than the nominal size.
2. Count every goldfish already in the aquarium at its adult size, not its current size.
3. Check the total against the table, then confirm the stocking level with our stocking calculator. If the numbers are tight, buy fewer fish or plan a larger aquarium.

Furnish the tank for long fins and big appetites

OATA recommends aquarium gravel or sand, and ideally live plants, while warning that fancy goldfish readily eat live plants; tough plants or good artificial plants, plant pots and model caves give shelter. To protect long fins and eyes, avoid ornaments and artificial plants with sharp or very rough edges. Keep the floor open enough for the fish to forage, because goldfish spend much of the day sifting the bottom for food.

Place the aquarium carefully. OATA says fancy goldfish do not tolerate extreme fluctuations in water temperature, so keep the tank away from draughts, radiators and direct sunlight, and away from loud noises, vibration and sudden movement. Overhead lighting keeps a proper day-night cycle; the RSPCA suggests eight to ten hours of light a day. A secure lid is optional but recommended in OATA’s equipment list.

Divide the floor by function

• Open front: clear swimming room and a feeding area where you can see every fish eat.
• Planted back and sides: robust plants or smooth artificial plants that will survive grazing.
• Smooth décor: rounded stones, wood or ornaments with no sharp edges for the tail to catch on.
• Filter outlet: spread along the back with a spray bar so the current stays gentle.

Keep cool, clean, medium-hard water

Fancy goldfish are not tolerant of poor water. OATA sets out the values below, and notes that the fish can acclimatise to a wider range of temperature, pH and hardness over time. The table also shows where the RSPCA and FishBase give different figures, so you can see the full picture.

Where the ranges overlap, 15–21°C and pH 6.5–8.0 satisfy every source. A heater is not needed unless the room is very cold, according to OATA. If you worry about swings in a cold room, the RSPCA suggests a thermostatic heater set at the lower end of the range.

Match your tap water to the range

Treat every drop of new water with a tap water conditioner, because chlorine or chloramine in tap water harms fish and filter bacteria; our water care range has conditioners and test kits. Test your tap water for pH, hardness and nitrate, then compare the results with the table using our water matcher. Our water chemistry guide explains what each reading means. Change water at the same temperature as the aquarium, so the fish never feel a sudden swing.

Filter for a heavy feeder and change water every week

A filter is always essential, OATA says, but fancy goldfish prefer a gentle current, so choose a filter rated for a heavy load of fish and spread its output with a spray bar. The aquarium must be fully cycled before any fish go in: the RSPCA recommends fishless cycling, testing every other day, and says cycling takes at least two weeks. Add fish only once ammonia and nitrite have risen and fallen back to zero. Our nitrogen cycle guide walks through the process, and our guide to aquarium filtration explains how to choose a filter.

Stock slowly. OATA warns that adding too many fish too quickly causes “new tank syndrome”, when there are not yet enough beneficial bacteria to cope with the extra waste and ammonia and nitrite rise to harmful levels.

Follow a weekly routine

1. Test ammonia, nitrite, nitrate, pH and hardness once a week and write the results down so you notice a change early.
2. Change at least 25% of the water every week, as OATA strongly recommends, siphoning solid waste from the gravel as you go.
3. Treat the new water with conditioner and match its temperature.
4. Check the filter flow. If the media needs cleaning, rinse it lightly in the aquarium water you have just removed, never under the tap.
5. Look at every fish while you work: fins, eyes, breathing and swimming.

Feed one measured meal a day

Fantails take most foods. OATA recommends a good-quality goldfish flake, granule or pellet, because goldfish need more carbohydrate than many other fish, and advises feeding only what the fish eat within a few minutes, once a day. Goldfish always act hungry, so it is easy to overfeed; uneaten food breaks down and poisons the water.

Some fancy goldfish swallow air when they feed at the surface and briefly lose their balance afterwards. OATA suggests trying a different food or a slow-sinking type if you see this. Small sinking foods such as Tropical Super Goldfish Mini Sticks suit 3–4 cm fish, and Tropical Goldfish Pellet suits larger fantails.

Build one measured meal

Introduce new fantails calmly

Transport is stressful, so get the box open and the fish into the aquarium without delay. OATA describes the floating-bag method: switch off the aquarium lights, take the bag out of its outer wrapping away from bright light and float it for 10 minutes so the temperatures match. Then add small amounts of aquarium water to the bag over up to 20 minutes, and net the fish into the tank with as little bag water as possible. Our guide on how to acclimatise new fish shows each step.

Use a first-week checkpoint plan

Choose slow, twin-tailed companions

Fantails are peaceful and unhurried. The RSPCA describes fancy goldfish as slow-moving, short-bodied fish with a twin tail, and OATA advises against keeping common goldfish with fancy varieties because the faster common fish out-compete them for food and boisterous ones sometimes nip their fins. Tropical fish are not suitable either: the RSPCA keeps goldfish at 10–21°C, well below the temperatures most tropical fish need.

Screen each companion

Before mixing, ask four questions: does the companion share the same temperature, does it swim at the same slow pace, will it reach a similar adult size, and does the aquarium have room for all of them as adults? Our tank mates tool checks a planned mix for you. Our Mixed Long-Fin Goldfish are another twin-tailed option. For the difference between fancy and pond goldfish, read our guides to comet goldfish and choosing cold water fish, or browse all our goldfish and coldwater fish.

Decide between an aquarium and a pond

This is where the sources disagree most. OATA says fancy goldfish are best kept in indoor aquaria only. BAS, on the other hand, describes fantails as hardy fish that live happily outdoors in ponds, and its breeder notes describe young fantails being brought on in ponds where they overwinter. In Practical Fishkeeping, fantail breeder Ray Rich writes that goldfish are easily tough enough to survive our winters.

Our advice is to keep fantails in an indoor aquarium, where you can see them every day, control the water and feed them without competition. If you do want them outdoors:

Set the pond up for slow fancy goldfish

• Keep them only with other twin-tailed fancy goldfish, never with comets, shubunkins or koi.
• OATA’s pond guide recommends a depth of at least 45–60 cm, which keeps the temperature more stable through hot spells and freezing weather.
• Net the pond against herons and other predators, and to stop new fish jumping out in their first weeks.
• Do not move fish from a warm room straight into a cold pond. Make the change in late spring when the pond has warmed.
• In winter, the RSPCA advises keeping a hole in the ice with a pond heater or de-icer, and never breaking ice by force.

Watch health signs 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. Most problems start with water quality, so test first whenever something looks wrong.

Pair each sign with an action

With good care fancy goldfish live a long time. OATA reports many fish living 6–8 years and rare reports of 20 years or more; BAS says fantails live for about 10 years. FishBase gives 41 years as the maximum reported age for the species as a whole.

Breed fantails in spring

Fantails spawn as the water warms in spring, and the sources give slightly different recipes. OATA suggests two males to each female and a slow rise in temperature to about 20°C, and notes that spawning often follows a partial water change. Practical Fishkeeping’s breeder starts around the beginning of March, warms the water to about 17°C, spawns one female with three males over plenty of hornwort, then raises the temperature to about 22°C once the adults are removed; the eggs hatch in three to four days. OATA gives about three days.

Remove the eggs or the adults straight after spawning, because fancy goldfish eat their eggs and fry. Feed the fry newly hatched brine shrimp and keep their water very clean. Expect to rear many more fry than you keep: Practical Fishkeeping’s breeder selects for properly divided tails from about two weeks old, and a BAS breeder keeps only about 20 fish from 3,000 fry a year. Interestingly, the two sources disagree on difficulty: BAS calls the fantail relatively easy to breed, while Practical Fishkeeping says it can be very challenging to breed well and consistently.

Answer fantail goldfish buying questions

What is a fantail goldfish?

A fancy goldfish, Carassius auratus, with a short, rounded body and a divided, forked twin tail that is held high and spreads like a fan when seen from above. It has a single dorsal fin and paired anal fins. It is the same species as the common goldfish, shaped by selective breeding.

What colour will my assorted fantail be?

The colour is not chosen. Fantails come in self colours such as red, orange, yellow, blue, brown or black, in variegated metallic mixes such as red and white, and in calico. The photographs show an orange-and-white example of the form, not the fish you will receive.

How big does a fantail goldfish get?

OATA says fancy goldfish are unlikely to grow larger than 20 cm. The size you choose (3–4 cm, 5–6 cm or 8–10 cm) is the size supplied, not the adult size, so plan the aquarium for a fish of up to 20 cm.

What size tank does a fantail need?

OATA advises at least 100 litres for one adult goldfish and an extra 50 litres for each additional adult, so two fantails need about 150 litres and three about 200 litres. A wide tank with a large water surface is better than a tall, narrow one.

Does a fantail goldfish need a heater?

No. OATA gives 4–25°C with 15–23°C as the optimum and says a heater is not needed unless the room is very cold. Avoid sudden temperature changes, draughts, radiators and direct sunlight.

Can fantails live in a garden pond?

Sources disagree. OATA says fancy goldfish are best kept in indoor aquaria only. The Bristol Aquarists’ Society describes fantails as hardy fish that live happily outdoors in ponds. We recommend an indoor aquarium; a summer pond is possible only with other slow fancy goldfish, never with comets or koi.

Can fantails live with comets or common goldfish?

It is better not to. OATA advises against keeping common goldfish with fancy varieties because the faster fish out-compete them for food and some nip their fins. Keep fantails with other twin-tailed fancy goldfish.

How many fantail goldfish should I buy?

The RSPCA says goldfish do not need the company of other fish, while FishBase notes goldfish in aquariums in groups of five or more. Many keepers choose two or three; the deciding factor is space, at about 50 extra litres per adult.

Consult the care references

• OATA: How to look after fancy goldfish and the printable care sheet — water values, size, tank volume, feeding, acclimatisation, companions, health and breeding.
• Bristol Aquarists’ Society: Fantail — the fantail standard, its colours, hardiness, lifespan and a breeder’s methods.
• Practical Fishkeeping: How to breed fantail goldfish — show points, common faults and a step-by-step spawning and rearing method.
• FishBase: Carassius auratus — native range, maximum size and age, pH and hardness range and aquarium notes for the species.
• RSPCA: Choosing an aquarium, Keeping fish together and Caring for fish in winter — space per goldfish, temperature, cycling, company and winter pond care.
• OATA: How to look after pond fish — pond depth, netting and winter care for goldfish outdoors.
• Cefas (GOV.UK): Spring viraemia of carp — signs and the legal duty to report this notifiable disease.
• Tropical Fish Co delivery policy — current dispatch days and Live Arrival Guarantee terms.