Can koi live with hillstream loaches?

Verdict

Yes, with care

Yes, with care. Koi and hillstream loaches can share a tank, but watch one thing. At 24 inches a koi can swallow a small hillstream loach. Fast, alert fish usually stay out of reach.

Koi59–77°F · pH 7–8.5

Hillstream loach68–75°F · pH 6.5–7.5

What to watch

Watch outAt 24 inches a koi can swallow a small hillstream loach. Fast, alert fish usually stay out of reach.

What works

Both are fine at 68–75°F.
pH 7–7.5 suits both.

Water side by side

The green band is the temperature range both can live in.

The green band is the pH both tolerate.

Size to scale

Adult length in an aquarium. A fish can swallow anything that fits in its mouth, roughly a third to half its own length for predators.

Care at a glance

	Koi	Hillstream loach
Temperature	59–77 °F	68–75 °F
pH	7–8.5	6.5–7.5
Adult size	24.0 in	2.5 in
Minimum tank	Pond	20 gal
Temperament	Peaceful	Peaceful
Swims at	All levels	Bottom
Group	Groups of 3+	Groups of 3+
Diet	Omnivore	Herbivore

Better tank mates for koi

All koi tank mates

Better tank mates for hillstream loaches

All hillstream loach tank mates

Questions

Can koi live with hillstream loaches?

Yes, with care. Koi and hillstream loaches can share a tank, but watch one thing. At 24 inches a koi can swallow a small hillstream loach. Fast, alert fish usually stay out of reach.

What temperature suits both koi and hillstream loaches?

68–75 °F. Koi need 59–77 °F, hillstream loaches need 68–75 °F.

What size tank do koi and hillstream loaches need together?

A pond. Koi outgrow indoor tanks.