Ryukin

Carassius auratus

Also known as: Ryukin goldfish, Japanese ryukin

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

One of the most distinctive fancy goldfish, the ryukin is instantly recognisable by the dramatic, pointed hump that rises steeply behind its head, giving it a deep, almost triangular body. It is one of the hardier and more robust fancies, an active and greedy feeder that competes well against other fancy varieties, and it comes in vivid red, red-and-white, and calico forms. Reaching 15 to 20cm, it carries the usual heavy goldfish bioload and needs a roomy, well-filtered aquarium with cool, clean, stable water. Its deep body makes it, like all round-bodied goldfish, somewhat prone to buoyancy and digestive trouble, best headed off with a sinking, easily-digested diet. A bold, colourful, and comparatively sturdy fancy, well-suited to a keeper stepping beyond the fantail.

Tankmates

A robust fancy goldfish that must be kept with other fancies of similar swimming ability, never with single-tailed goldfish (commons, comets, shubunkins), which are far too fast and outcompete it at every meal. It sits comfortably alongside fantails and orandas. Avoid the slowest, most delicate fancies (bubble eyes, ranchu, pearlscales), which even a ryukin will beat to food, and avoid small fish and shrimp. Like all fancies it needs a spacious, well-filtered aquarium and cool but not cold, very stable water.

Compatible with

• Fantail Goldfish
• Oranda

Avoid keeping with

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

Common Problems

• swim bladder and buoyancy issues from its deep body
• 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