Fantail Goldfish

Carassius auratus

Also known as: Fantail, Fancy fantail

Water Parameters

• Temperature: 16–24°C
• pH: 7–8.4
• Hardness (GH): 89–357 ppm (5–20 dGH)

Values above are general hardness (GH). For carbonate hardness (KH), the buffer that keeps pH stable, see the water parameters guide.

Care Summary

The gateway to fancy goldfish: an egg-bodied, twin-tailed variety with a graceful split, forked fantail, and the sturdiest constitution of any of the fancies. Where the round-bodied goldfish are prone to swim bladder and balance problems, the fantail is comparatively robust, which makes it the sensible first choice for anyone moving from single-tails into the fancy world. It reaches 15 to 20cm, carries a heavy bioload like all goldfish, and needs a roomy, filtered aquarium with cool, clean, stable water rather than the bowl it is so often sold for. Kept with other similarly-paced fancies and fed a sinking, easily-digested diet to spare its compressed gut, it is a hardy, personable, long-lived fish, and much the safest way to begin keeping fancy goldfish.

Tankmates

The hardiest of the fancy goldfish and the best fancy for a first-time keeper, but still a fancy, which means it must not be mixed with single-tailed goldfish (commons, comets, shubunkins), whose speed lets them outcompete and stress the slower, round-bodied fantail at feeding. It pairs well with other robust fancies of similar swimming ability, such as ryukins and orandas. Avoid the slowest, most delicate fancies (bubble eyes, pearlscales, ranchu), which even a fantail will outcompete, and avoid nano fish and shrimp, which are eaten or outmuscled. A fancy goldfish needs a spacious, well-filtered aquarium rather than a bowl, and does best in cool but not cold water.

Compatible with

• Ryukin
• Oranda

Avoid keeping with

• Common Goldfish
• Comet Goldfish
• Shubunkin
• Ranchu
• Bubble Eye
• Pearlscale
• Cherry Shrimp
• Tropical Warm Water Species

Common Problems

• swim bladder and buoyancy issues (though less than other fancies)
• being outcompeted by faster single-tailed goldfish
• constipation and bloat from floating or protein-heavy food
• heavy bioload demanding strong filtration

Sources: seriouslyfish.com, fishbase.org · Last updated: 2026-06-20