Broadtail moor

Carassius auratus

Black colour, prominent eyes and a broad flowing double tail

The British broadtail-moor standard emphasizes black colour, spherical protruding eyes and a broad veil-like double tail. Black telescope fish sold elsewhere may have other tail shapes; black colour alone is insufficient. The broad veil tail versus the more clearly forked globe-eye tail is a form-standard distinction, not a species split.

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.

Protect protruding eyes and long fins from sharp or abrasive decor, and monitor feeding access with faster companions. 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 British broadtail-moor standard emphasizes a broad, minimally forked veil tail; the globe-eye standard retains a more clearly forked tail. Regional eye shapes and trade names overlap.

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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