Not furry, but we like them anyway.
Sarasa Comet
Carassius auratus
Also called Sarasa comet goldfish, Red-and-white comet
From Colour form of the comet goldfish; the comet type was developed in the USA in the 1880s, while the red-and-white sarasa colouring is described as originating in China, with a Japanese-derived name12
At a glance the quick version
Looks how to spot one
Scaled fish with metallic scales and a single, long, deeply forked tail
A slim, streamlined goldfish with a single tail that is long and deeply forked, ending in pointed tips that spread like an open pair of scissors. The body is shallower than a common goldfish. The sarasa colouring is a crisp mix of bright red and clean white, often arranged in bold patches much like a red-and-white koi.132
Personality what they are like
Lively, playful and curious. Comets like to dash back and forth and are peaceful with other fish of similar size and speed.14
Daily activity how busy a day looks
High. A quick, energetic swimmer that needs long, open swimming space; it is very much at home in a garden pond.13
Grooming and care the hands-on bits
A coldwater fish that normally needs no heater; about 16 to 21 C suits single-tailed goldfish, and pH guidance ranges from 6.0 to 8.0 (FishBase) to 7.0 to 8.4 (Aqueon). Good filtration and regular partial water changes with dechlorinated water are part of routine care.456
Home where they are happiest
Plenty of room: about 75 litres (20 US gallons) per adult is a common guideline, and FishBase gives a minimum tank length of 100 cm for the species. Fast single-tailed goldfish do especially well in a well-kept garden pond once mature, and in temperate climates they can stay outdoors all year.457
Food basics what goes in the bowl
Omnivores. Offer a goldfish-specific pellet as the staple, which suits their need for less protein and more carbohydrate than many fish foods. Add chopped vegetables such as peas or spinach and small amounts of daphnia or brine shrimp as treats. Feed two or three small meals a day, giving only what is eaten within two to five minutes.87
Company who they like around
Sociable and peaceful with similar-sized fish; FishBase suggests groups of five or more goldfish. Best kept with other fast, single-tailed goldfish such as common goldfish, comets and shubunkins, or in a pond, rather than with slow fancy twin-tailed types.549
The story where it all began
The comet goldfish first turned up in the 1880s in the ponds of the U.S. Government Fish Commission in Washington, D.C., and Hugo Mulertt went on to breed and popularise it. The red-and-white sarasa form is described as coming from China, though its name is Japanese, and it became one of the best-loved comet colours for ponds.1
Fun facts for the dinner table
- 1
The sarasa pattern looks so much like a red-and-white koi that the two are often compared side by side.1
- 2
The comet is one of the few goldfish types created in the West rather than in China or Japan, and it became the most common variety in the United States.10
- 3
A show comet's tail should ideally reach about three quarters of its body length.3
- 4
In East Asia comets are sometimes called swallowtails because of their scissor-like tails.3
Recognised by the official bits
- Goldfish Society of Great Britain (GSGB)
- The comet is one of the society's standard varieties; red-and-white sarasa fish fall under the variegated metallic colouring allowed for comets2
- Bristol Aquarists' Society / goldfish-types.info
- Comet standard: slender body about 35% as deep as long, single deeply forked tail with pointed lobes, minimum body length 7.5 cm; metallic fish may be self-coloured or variegated3
The care rhythm Furry Diary remembers it for you
A typical home-care rhythm for a Sarasa Comet. It is our own starting plan, not a vet's advice, and you can change every line in the app.
- Feedingevery day
- Water changeAbout 25 to 30% of the waterevery week
- Water testevery week
- Glass cleanevery week
- Filter rinseevery month
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Where this comes from
Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at support@furrydiary.app and we will fix it.
- Comet (goldfish) - Wikipedia en.wikipedia.orgused for origin, history, sarasa colouring, lifespan, temperament
- Goldfish Society of Great Britain - Varieties goldfishsociety.co.ukused for comet standard listing and variegated colouring
- Comet goldfish standard - goldfish-types.info (successor to the Bristol Aquarists' Society site) goldfish-types.infoused for comet standard, tail, swallowtail name
- Aqueon - Goldfish care sheet aqueon.comused for temperature, pH, tank volume, diet
- Carassius auratus - FishBase fishbase.seused for pH, tank size, group size
- RSPCA - Fish environment rspca.org.ukused for tank volume, water changes, filtration
- Goldfish - Wikipedia en.wikipedia.orgused for general goldfish care, lifespan, temperature, diet
- RSPCA - Fish diet rspca.org.ukused for diet and feeding routine
- RSPCA - Keeping fish together rspca.org.ukused for social needs
- List of goldfish varieties - Wikipedia en.wikipedia.orgused for variety summary
Checked 2026-09-30. Text is written in our own words from these sources.