TankmateChecker

Can koi live with swordtails?

Verdict

Yes, with care

Yes, with care. Koi and swordtails can share a tank, but watch one thing. A grown koi may treat small swordtails as food, especially at night.

Koi

Koi59–77°F · pH 7–8.5

Swordtail

Swordtail72–79°F · pH 7–8.3

What to watch

Watch outA grown koi may treat small swordtails as food, especially at night.

What works

Both are fine at 72–77°F.
pH 7–8.3 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	Swordtail
Temperature	59–77 °F	72–79 °F
pH	7–8.5	7–8.3
Adult size	24.0 in	5.0 in
Minimum tank	Pond	30 gal
Temperament	Peaceful	Semi-aggressive
Swims at	All levels	Middle
Group	Groups of 3+	Groups of 3+
Diet	Omnivore	Omnivore

Better tank mates for koi

All koi tank mates

Better tank mates for swordtails

All swordtail tank mates

Questions

Can koi live with swordtails?

Yes, with care. Koi and swordtails can share a tank, but watch one thing. A grown koi may treat small swordtails as food, especially at night.

What temperature suits both koi and swordtails?

72–77 °F. Koi need 59–77 °F, swordtails need 72–79 °F.

What size tank do koi and swordtails need together?

A pond. Koi outgrow indoor tanks.