Comet goldfish, Carassius auratus auratus


The Comet goldfish makes a great choice for the pond or larger aquarium.

Common name: Comet goldfish

Scientific name: Carassius auratus auratus

Origin: China

Size: To 35cm/14”

Diet: Natural foods include insects and their larvae, aquatic invertebrates, plants and detritus. In the aquarium or pond they will accept a wide range of dry and frozen foods.

Water: Goldfish and their varieties prefer slightly hard, alkaline water, pH 7.5-8.5. In nature they experience seasonal variations from 4°C/39°F to the 20s°C/75°+F, though are happiest between 10°C/50°F and 20°C/68°F.

Notes: Comets are now the world’s most common goldfish variety, as many standard single-tail goldfish we buy for tanks and ponds have an elongated, comet tail. They are large fish, regularly reaching 30cm/12” in length, and so are best kept in filtered outdoor ponds or very large aquaria.

Like all single-tail goldfish they are naturally hardy, though often abused through ignorance.

Popular is the red and white pond fish known as Sarasa comet. Having deep red and pure white coloration, they are attractive, hardy and large fish.

Left to their own devices, comets will breed and cross-breed with short-tailed Common goldfish and Shubunkins.

To line breed for finnage and colour these fish must be selected and culled where necessary to prevent them reverting back to olive green, wild type goldfish.

The correct comet tail should be forked and well spread, and not droop or overlap.

Avoid fish with blood visible in fins as this may be a result of poor water quality and/or poor health.

Aquarium: Best kept in a pond, though if indoors the larger the aquarium the better — preferably 120cm/48” minimum, though 150cm/60” or even 180cm/72” are best long term.

All goldfish are messy, especially when large, so an external is the best filter.

Don’t think of combining these with twin-tailed fancy goldfish as the faster comets may outcompete them.

Sexing: Males develop breeding tubercles, white spots on the gill covers, and ridges on their pectoral fins. Females become plump with eggs and become lopsided when viewed from above. Males are more slender.

Identification: Any goldfish with the characteristic comet tail is classed as a comet, be it metallic orange, red and white or calico.

Availability: Widely available from anywhere that sells aquarium and pond fish.

Price: £1 each upwards, though a lot more for larger and high quality fish.