Koi tank mates
Cyprinus rubrofuscus
6 rated pairings from the Koi care guide. Compatibility here means water, temperament, tank zone and adult size all line up — the note on each card says why. Koi needs at least 250 gallons on its own; every companion adds to that.
Excellent matches
3 · Same water, complementary zones, no conflict.Comet Goldfish
Carassius auratus
40 gal min · 12" adult · Peaceful
Similar water temperature requirements and peaceful temperament; both are large, hardy pond fish
Shubunkin Goldfish
Carassius auratus
40 gal min · 12" adult · Peaceful
Shares the same cool-water preferences and peaceful nature, thrives alongside koi
Common Goldfish
Carassius auratus
50 gal min · 12" adult · Peaceful
Compatible water parameters and temperament; both species coexist well in large setups
Good matches
2 · Compatible with normal care — watch space and numbers.Dojo Loach
Misgurnus anguillicaudatus
30 gal min · 6" adult · Peaceful
Prefers similar cool water temperatures and is large enough not to be threatened by koi
Chinese Trapdoor Snail
Bellamya chinensis
20 gal min · 2.5" adult · Peaceful
Hardy snail that tolerates cool water and helps with algae control in koi ponds
Use caution
1 · Works in the right setup; read the note before combining.Also recommended alongside Koi
Species whose own guides list Koi as a tank mate.
Planning this tank?
Run the whole stock list through the calculator — it checks bioload and schooling numbers, not just pairings.