Comet goldfish

Carassius auratus

Slender body with a long, deeply forked single tail

The long pointed lobes form one caudal fin, not a divided double tail. Compared with common goldfish, comets have a slimmer outline and much longer tail. Calico forms also occur, so colour alone does not establish the variety.

Adult length: About 10 cm
Lifespan: Up to 30 years
pH: 7–8.4
Hardness: 5–19 dGH

Natural habitat: Wild habitats include rivers, lakes, ponds and ditches, often in vegetated still or slow water; ornamental goldfish are domesticated forms.

Active swimming and feeding can disadvantage smaller, slower double-tailed fish. Pond suitability is conditional on climate, depth and maintenance. Swimming and feeding ability vary among forms. A shared species name or overlapping temperatures does not establish compatibility. Provide filtration, oxygenation and maintenance.

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Appearance and identification

The comet has a longer, more deeply forked tail with pointed lobes than the common goldfish.

Same-species behaviour

Assess individual swimming and feeding; a group size suitable for every form remains unknown.

Space requirements

A dimensioned adult housing plan remains unverified. Avoid small, unfiltered containers.

Diet and feeding

Use an appropriate goldfish diet with suitable varied foods, adjusting to condition and water quality.

Compatibility limits

Active single-tailed fish may outcompete slower double-tailed forms. Avoid fin nippers and overly competitive companions.

Aquarium environment

Goldfish may eat or uproot plants; aquarium illustrations do not establish plant safety.

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