Koi tank mates

Good matches

8 of 98

The safest picks for koi are goldfish, black ghost knives and bichirs. Each match shares koi' temperature and pH and leaves them alone.

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

Temperature

59–77°F

pH

7–8.5

Temperament

Peaceful

Minimum tank

Pond

With care

50

Avoid

40

Good tank mates

• Goldfish60–74°F
• Black ghost knife73–77°F
• Bichir72–77°F
• Bala shark72–77°F
• Kissing gourami72–77°F
• Common pleco72–77°F
• Tinfoil barb72–77°F
• Elephant nose fish73–77°F

Possible, with care

• Crayfish A grown koi may treat small crayfish as food, especially at night.
• Mystery snail Large koi crack or pick at small snails. A big mystery snail has better odds than a ramshorn.
• Zebra danio At 24 inches a koi can swallow a small zebra danio. Fast, alert fish usually stay out of reach.
• White cloud minnow At 24 inches a koi can swallow a small white cloud minnow. Fast, alert fish usually stay out of reach.
• Paradise fish At 24 inches a koi can swallow a small paradise fish. Fast, alert fish usually stay out of reach.
• Dojo loach A grown koi may treat small dojo loaches as food, especially at night.
• Gold barb At 24 inches a koi can swallow a small gold barb. Fast, alert fish usually stay out of reach.
• Guppy At 24 inches a koi can swallow a small guppy. Fast, alert fish usually stay out of reach.
• Platy At 24 inches a koi can swallow a small platy. Fast, alert fish usually stay out of reach.
• Nerite snail Large koi crack or pick at small snails. A big mystery snail has better odds than a ramshorn.
• Rosy barb At 24 inches a koi can swallow a small rosy barb. Fast, alert fish usually stay out of reach.
• Corydoras At 24 inches a koi can swallow a small corydoras. Fast, alert fish usually stay out of reach.
• Panda cory At 24 inches a koi can swallow a small panda cory. Fast, alert fish usually stay out of reach.
• Fancy goldfish A grown koi may treat small fancy goldfish as food, especially at night.
• Hillstream loach At 24 inches a koi can swallow a small hillstream loach. Fast, alert fish usually stay out of reach.
• Ramshorn snail Large koi crack or pick at small snails. A big mystery snail has better odds than a ramshorn.
• Swordtail A grown koi may treat small swordtails as food, especially at night.
• Molly At 24 inches a koi can swallow a small molly. Fast, alert fish usually stay out of reach.
• Blue gourami A grown koi may treat small blue gouramis as food, especially at night.
• Tiger barb At 24 inches a koi can swallow a small tiger barb. Fast, alert fish usually stay out of reach.
• Black skirt tetra At 24 inches a koi can swallow a small black skirt tetra. Fast, alert fish usually stay out of reach.
• Jack Dempsey Jack dempseys are aggressive, though koi are big enough to shrug most of it off.
• Rainbow shark A grown koi may treat small rainbow sharks as food, especially at night.
• Odessa barb At 24 inches a koi can swallow a small odessa barb. Fast, alert fish usually stay out of reach.
• Red tail shark A grown koi may treat small red tail sharks as food, especially at night.
• Honey gourami At 24 inches a koi can swallow a small honey gourami. Fast, alert fish usually stay out of reach.
• Pictus catfish A grown koi may treat small pictus catfish as food, especially at night.
• Neon tetra Water chemistry is a squeeze. The only pH that suits both is around 7.
• Endler's livebearer At 24 inches a koi can swallow a small endler's livebearer. Fast, alert fish usually stay out of reach.
• Celestial pearl danio At 24 inches a koi can swallow a small celestial pearl danio. Fast, alert fish usually stay out of reach.
• Bolivian ram At 24 inches a koi can swallow a small bolivian ram. Fast, alert fish usually stay out of reach.
• Bristlenose pleco A grown koi may treat small bristlenose plecos as food, especially at night.
• Otocinclus At 24 inches a koi can swallow a small otocinclus. Fast, alert fish usually stay out of reach.
• African dwarf frog At 24 inches a koi can swallow a small african dwarf frog. Fast, alert fish usually stay out of reach.
• Sparkling gourami At 24 inches a koi can swallow a small sparkling gourami. Fast, alert fish usually stay out of reach.
• Killifish Water chemistry is a squeeze. The only pH that suits both is around 7.
• Harlequin rasbora At 24 inches a koi can swallow a small harlequin rasbora. Fast, alert fish usually stay out of reach.
• Upside down catfish At 24 inches a koi can swallow a small upside down catfish. Fast, alert fish usually stay out of reach.
• Serpae tetra At 24 inches a koi can swallow a small serpae tetra. Fast, alert fish usually stay out of reach.
• Electric blue acara A grown koi may treat small electric blue acaras as food, especially at night.
• Congo tetra At 24 inches a koi can swallow a small congo tetra. Fast, alert fish usually stay out of reach.
• Cherry barb At 24 inches a koi can swallow a small cherry barb. Fast, alert fish usually stay out of reach.
• Lemon tetra At 24 inches a koi can swallow a small lemon tetra. Fast, alert fish usually stay out of reach.
• Dwarf gourami At 24 inches a koi can swallow a small dwarf gourami. Fast, alert fish usually stay out of reach.
• GloFish tetra At 24 inches a koi can swallow a small glofish tetra. Fast, alert fish usually stay out of reach.
• Pygmy cory At 24 inches a koi can swallow a small pygmy cory. Fast, alert fish usually stay out of reach.
• Clown pleco At 24 inches a koi can swallow a small clown pleco. Fast, alert fish usually stay out of reach.
• Zebra loach At 24 inches a koi can swallow a small zebra loach. Fast, alert fish usually stay out of reach.
• Black neon tetra At 24 inches a koi can swallow a small black neon tetra. Fast, alert fish usually stay out of reach.
• Ember tetra Water chemistry is a squeeze. The only pH that suits both is around 7.

Avoid

• 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.
• Convict cichlid Koi are coldwater animals (59–77°F); convict cichlids need 74–82°F. They overlap only at 74–77°F, the edge of both ranges.
• Chinese algae eater Koi are coldwater animals (59–77°F); chinese algae eaters need 74–80°F. They overlap only at 74–77°F, the edge of both ranges.
• Kuhli loach Koi are coldwater animals (59–77°F); kuhli loaches need 75–86°F. They overlap only at 75–77°F, the edge of both ranges.
• Firemouth cichlid Koi are coldwater animals (59–77°F); firemouth cichlids need 75–86°F. They overlap only at 75–77°F, the edge of both ranges.
• Bamboo shrimp A koi is big enough to swallow adult bamboo shrimp.
• Boesemani rainbowfish Koi are coldwater animals (59–77°F); boesemani rainbowfish need 75–82°F. They overlap only at 75–77°F, the edge of both ranges.
• Flowerhorn Koi are coldwater animals (59–77°F); flowerhorns need 80–89°F. No temperature suits both.
• Assassin snail Koi are coldwater animals (59–77°F); assassin snails need 75–80°F. They overlap only at 75–77°F, the edge of both ranges.
• Yoyo loach Koi are coldwater animals (59–77°F); yoyo loaches need 75–86°F. They overlap only at 75–77°F, the edge of both ranges.
• Blood parrot Koi are coldwater animals (59–77°F); blood parrots need 76–80°F. They overlap only at 76–77°F, the edge of both ranges.
• Siamese algae eater Koi are coldwater animals (59–77°F); siamese algae eaters need 75–79°F. They overlap only at 75–77°F, the edge of both ranges.
• Glowlight tetra Koi are coldwater animals (59–77°F); glowlight tetras need 74–80°F. They overlap only at 74–77°F, the edge of both ranges.
• Glass catfish Koi are coldwater animals (59–77°F); glass catfish need 75–80°F. They overlap only at 75–77°F, the edge of both ranges.
• Kribensis Koi are coldwater animals (59–77°F); kribensis need 75–80°F. They overlap only at 75–77°F, the edge of both ranges.
• Peacock cichlid Koi are coldwater animals (59–77°F); peacock cichlids need 76–82°F. They overlap only at 76–77°F, the edge of both ranges.
• Severum Koi are coldwater animals (59–77°F); severums need 74–84°F. They overlap only at 74–77°F, the edge of both ranges.
• Discus Koi are coldwater animals (59–77°F); discus need 82–88°F. No temperature suits both.
• Hatchetfish Koi are coldwater animals (59–77°F); hatchetfish need 75–81°F. They overlap only at 75–77°F, the edge of both ranges.
• Pencilfish Koi are coldwater animals (59–77°F); pencilfish need 75–82°F. They overlap only at 75–77°F, the edge of both ranges.
• Dwarf neon rainbowfish Koi are coldwater animals (59–77°F); dwarf neon rainbowfish need 75–82°F. They overlap only at 75–77°F, the edge of both ranges.
• Clown loach Koi are coldwater animals (59–77°F); clown loaches need 77–86°F. They meet only at 77°F, the edge of both ranges.
• African cichlid Koi are coldwater animals (59–77°F); african cichlids need 75–82°F. They overlap only at 75–77°F, the edge of both ranges.
• Pearl gourami Koi are coldwater animals (59–77°F); pearl gouramis need 77–82°F. They meet only at 77°F, the edge of both ranges.
• Silver arowana Koi are coldwater animals (59–77°F); arowanas need 75–86°F. They overlap only at 75–77°F, the edge of both ranges.
• Chili rasbora Koi are coldwater animals (59–77°F); chili rasboras need 75–82°F. They overlap only at 75–77°F, the edge of both ranges.
• Rummy nose tetra Koi are coldwater animals (59–77°F); rummy nose tetras need 75–84°F. They overlap only at 75–77°F, the edge of both ranges.
• Silver dollar Koi are coldwater animals (59–77°F); silver dollars need 75–82°F. They overlap only at 75–77°F, the edge of both ranges.
• Apistogramma Koi are coldwater animals (59–77°F); apistogramma need 75–84°F. They overlap only at 75–77°F, the edge of both ranges.
• Zebra pleco Koi are coldwater animals (59–77°F); zebra plecos need 79–88°F. No temperature suits both.
• Electric yellow cichlid Koi are coldwater animals (59–77°F); yellow labs need 75–82°F. They overlap only at 75–77°F, the edge of both ranges.
• German blue ram Koi are coldwater animals (59–77°F); rams need 80–86°F. No temperature suits both.
• Cardinal tetra Koi are coldwater animals (59–77°F); cardinal tetras need 76–84°F. They overlap only at 76–77°F, the edge of both ranges.

Planning a mixed tank? The tank mate checker tests every pair at once. Or read the koi care sheet.