Canary Yellow Goldfish (Carassius auratus)

Choose a canary yellow goldfish for the garden pond

The Canary Yellow Goldfish is a lemon-yellow colour form of the goldfish, Carassius auratus, the domesticated member of the carp family Cyprinidae. OATA records that goldfish were first kept in bowls in China in the third century and reached Europe in the 1700s, and it lists yellow among today’s goldfish colours alongside red, orange, white, black and blue. This yellow goldfish is a single-tailed type, with a long, streamlined body built for swimming rather than the short, round shape of the fancy varieties, which is why it suits an outdoor pond.

The fish in our photographs has the long fins and deeply forked tail of a comet-type goldfish. Comets were developed in the United States in the 1880s from the common goldfish; they are slimmer than commons, very active and often described as the goldfish best suited to ponds. Fin length varies between individuals of this colour form, so we sell it as a single-tailed yellow goldfish and do not promise comet finnage.

Know which kind of goldfish you are buying

Compare it with the other single-tailed goldfish in our Goldfish category and the wider goldfish and coldwater fish range, and read our comet goldfish guide for more on how single-tailed goldfish grow. The gallery photographs are representative of the colour form; none shows the exact fish you will receive.

Select the size and the number of fish

One purchase quantity supplies one live goldfish of the size you select: 2–3 in (about 5–8 cm), 3–4 in (about 8–10 cm), 4–5 in (about 10–13 cm) or 5–6 in (about 13–15 cm). Sizes are approximate, and shade, fin length and body shape vary from fish to fish. Every size grows into the same adult: OATA’s pond fish care sheet gives a most common maximum body length of up to 30 cm for goldfish.

Match the size to where the fish will live

Young goldfish cannot be sexed by eye, so sex is not specified. In spring and summer, OATA notes, males develop small white tubercles on the gill covers and pectoral fins and females become deeper-bodied.

Colour can change with age. In a Practical Fishkeeping answer, Paul Green notes that goldfish colours shift as fish mature and that many become whiter with age, though the rate varies from fish to fish. A canary yellow fish may become paler or deeper over the years; the photographs show the colour form when it is sold, not a guarantee for life.

Plan the pond for a 30 cm fish

Goldfish stay smaller than koi, orfe and tench, which is why OATA describes them as suitable for most smaller pond systems. Plan for an adult of up to 30 cm, and remember that goldfish can live for many years: OATA cites reports of goldfish living up to 20 years, and FishBase records a maximum reported age of 41 years.

Depth is the most important measurement. OATA advises a fish pond at least 45–60 cm deep: deeper water keeps temperatures more stable, gives a cool zone at the bottom in hot spells and a warmer refuge at the bottom in freezing winters.

Check the pond against OATA’s list

If you plan to add bigger fish later, OATA recommends a pond of 4,500 litres or more for koi, tench and orfe, which can reach 75 cm. Goldfish on their own do not need that volume, but stock slowly so the filter keeps up, and ask us if you are unsure how many fish your pond can hold.

Grow young fish on indoors when it helps

Young single-tailed goldfish can spend their first months in an aquarium. OATA gives at least 100 litres for one goldfish plus 50 litres for each further adult, a filter in every tank and no heater unless the room is very cold, and notes that non-fancy goldfish can later move to an outdoor pond. In aquariums OATA says up to 25 cm is the more common size, with reports of goldfish passing 40 cm, so a single-tailed goldfish will outgrow most home aquariums in time.

Use an unheated aquarium as a nursery

• A filtered, cycled aquarium of at least 100 litres; work out its real volume with our tank volume calculator.
• Rounded gravel, hardy plants and plenty of open swimming space.
• A small goldfish food such as Tropical Super Goldfish Mini Sticks once a day.
• Weekly tests, and a change of at least 25% of the water every week.
• A move outdoors in the warmer months, matching temperatures with the floating-bag method.

If your fish arrive in deep winter, when a pond may be close to freezing and OATA suggests feeding may stop below about 8°C, growing them on indoors until spring is a sensible option. A fish moved from a warm room into near-freezing water faces a much larger temperature change than it would in late spring.

Keep pond water within goldfish values

OATA notes that pond fish tolerate a range of conditions, but ponds are exposed to weather and other outside changes, so frequent testing is essential. Its values for pond fish are below; OATA’s aquarium goldfish sheet gives 4–25°C and pH 6.0–8.0 for goldfish kept indoors.

Test against one table

FishBase records goldfish in the wild across 0–41°C, but that is a survival range, not a target: stable water inside OATA’s range is what keeps pond fish healthy. Nitrate and phosphate also feed blanketweed and green water, so keeping them low improves the view as well as the fish’s health.

UK tap water varies from soft to very hard by region. Test yours and compare it with these values in our water matcher; our aquarium water parameters guide explains each reading. Treat tap water used to top up the pond with a conditioner that removes chlorine and chloramine.

Maintain the pond through the seasons

Goldfish metabolism and appetite follow the water temperature, so pond care changes with the seasons. These tasks come from OATA’s pond care sheet.

Follow a seasonal routine

Service the filter according to its type, size and stocking, and watch its flow as a sign it is working. Never rinse filter media under the tap: rinse it lightly in pond water removed during a partial water change so the bacteria survive. If the system has an ultraviolet clarifier, OATA advises replacing the bulb yearly unless the manufacturer says otherwise.

Feed your yellow goldfish by water temperature

Most pond fish are omnivores; in the wild FishBase records goldfish eating plankton, bottom-living invertebrates, plant material and detritus. OATA advises feeding pond fish only what they eat within a few minutes, once a day, and notes that goldfish may prefer a balanced floating food.

Match the food to the season

Overfeeding is the most common pond mistake: uneaten food breaks down and releases toxic waste, and OATA warns against over-feeding in very warm summers. Colour-enhancing foods are available if you want to bring out the yellow, but a varied, measured diet matters more.

Introduce the fish to the pond

Before the fish arrive, check that ammonia and nitrite are zero and that the pond is filtered and mature. Add fish gradually: every addition increases the waste the filter bacteria must handle, and stocking too fast can cause what OATA calls new pond syndrome, with rising ammonia and nitrite that can make fish ill or kill them.

Use the floating-bag method

1. Unpack the bag away from bright light.
2. Float the sealed bag in the pond for about 10 minutes so the temperatures match.
3. Slowly add small amounts of pond water to the bag.
4. Release the fish with as little bag water as possible.
5. Dispose of the bag and its water appropriately.
6. Watch the fish and the water quality closely for the first week.

Fish often try to jump out in their first couple of weeks in a new pond, so OATA suggests netting it after adding fish. Our guide to acclimatising new fish covers the method in more detail, and our delivery information explains delivery days and the Live Arrival Guarantee.

Choose pond companions

OATA describes most pond fish as compatible with one another, but their needs differ. Single-tailed goldfish of similar size are the simplest companions. Larger species need a bigger pond: koi, tench and orfe can reach 75 cm and are best in 4,500 litres or more, and orfe should be kept in groups of four or five. Rudd stay smaller, rarely over 40 cm, and also benefit from a group.

Use a suits and avoid list

Our tank mate checker screens other species, and our cold water fish buying guide compares the main pond and coldwater fish. Never release goldfish or any pond fish into the wild: OATA points out that it is illegal, and survivors can harm native wildlife.

Watch the fish and act on changes

OATA describes healthy pond fish as having clear, bright eyes, undamaged fins, intact scales, no ulcers or bumps, normal swimming and steady breathing. Check them at feeding time, when they gather at the surface.

Pair each sign with an action

Do not diagnose from a single sign. If a problem continues after the water checks, contact us with the pond volume, depth, temperature, pH, ammonia, nitrite and nitrate readings and the other fish in the pond.

Expect spawning in a planted pond

OATA describes goldfish as the pond fish most likely to breed. Spawning is likeliest when there are more adult males than females and the water warms in late spring. FishBase notes that females lay sticky eggs on submerged plants, and OATA’s aquarium sheet says the eggs hatch within three days, with dark-coloured fry visible within a few days.

Help some fry survive

• Provide a shallow, heavily planted area, as OATA recommends, so some fry can hide.
• Expect losses: goldfish are poor parents and eat their own eggs and fry.
• Look closely: the fry are dark-coloured at first and easy to miss.
• Plan homes for extra fish before the pond fills up; never release them into the wild.

Answer Canary Yellow Goldfish buying questions

Is the Canary Yellow Goldfish a pond fish?

Yes. It is a single-tailed goldfish, and single-tailed goldfish can live outdoors all year in the UK in a filtered pond at least 45–60 cm deep, with part of the surface kept free of ice in winter.

How big does a yellow goldfish grow?

OATA gives a most common maximum of up to 30 cm for goldfish in ponds; in aquariums up to 25 cm is more common. Every size we sell grows to the same adult size.

How long do goldfish live?

Many years in good water. OATA cites reports of goldfish living up to 20 years, and FishBase records a maximum reported age of 41 years.

Can I keep a Canary Yellow Goldfish in an aquarium?

Young fish can be grown on in an unheated, filtered aquarium of at least 100 litres, plus 50 litres for each further adult, but a single-tailed goldfish eventually needs a pond or a very large aquarium.

Can it live with fancy goldfish?

It is better not to mix them. Single-tailed goldfish swim faster and take most of the food from slower fancy varieties, and some boisterous goldfish nip their fins.

What should I feed pond goldfish in winter?

Switch to a lower-protein wheatgerm food as the water cools in autumn. Below about 8°C it may be better not to feed at all; restart slowly in spring.

Will it stay yellow?

Goldfish colours can change with age, and many goldfish become whiter as they mature, so the yellow may pale or deepen over the years.

Which sizes can I choose?

2–3 in, 3–4 in, 4–5 in or 5–6 in, roughly 5 to 15 cm. One purchase quantity is one fish.

Consult the care references

• OATA: How to care for pond fish (September 2022) — pond values, depth, size, equipment, seasons, feeding, compatibility and breeding.
• OATA: How to look after goldfish in an aquarium — history and colours, aquarium size and values, sexing and egg hatching.
• OATA: How to look after fancy goldfish — fancy goldfish size and indoor keeping, for comparison.
• FishBase: Carassius auratus — family, wild diet, eggs, temperature tolerance and maximum reported age.
• Wikipedia: Comet (goldfish) — origin and shape of the comet type and its suitability for ponds.
• Practical Fishkeeping: Will my red, black and white goldfish lose the black colour with age? — colour change with age.