Koi care

Water temperature

59–77°F

Koi are pond fish. They do best at 59–77°F and pH 7–8.5, and adults outgrow any indoor tank. Good tank mates include goldfish, black ghost knives, bichirs.

A pond fish. Indoor tanks are too small for adults.

Cyprinus rubrofuscus

pH: 7–8.5
Minimum tank: Pond
Adult size: 24.0 in
Temperament: Peaceful
Group: Groups of 3+
Lifespan: 25–35 years
Swims at: All levels
Diet: Omnivore

Best tank mates

Full koi tank mate chart: 8 yes, 50 with care, 40 no

Koi water compared

Koi next to its best tank mates. Overlap is what lets two species share a heater setting.

pH range. Tap water in most US cities sits between 7 and 8.

Adult size to scale.

Fish to keep away from koi

Axolotl Fish nibble at axolotl gills, and axolotls swallow small fish. Keep axolotls on their own.
Betta Koi are coldwater animals (59–77°F); bettas need 76–82°F. They overlap only at 76–77°F, the edge of both ranges.
Cherry shrimp A koi is big enough to swallow adult cherry shrimp.
Ghost shrimp A koi is big enough to swallow adult ghost shrimp.
Pea puffer Koi are coldwater animals (59–77°F); pea puffers need 74–82°F. They overlap only at 74–77°F, the edge of both ranges.
Oscar Koi are coldwater animals (59–77°F); oscars need 74–81°F. They overlap only at 74–77°F, the edge of both ranges.
Amano shrimp A koi is big enough to swallow adult amano shrimp.
Angelfish Koi are coldwater animals (59–77°F); angelfish need 76–84°F. They overlap only at 76–77°F, the edge of both ranges.