Can koi live with platies?

Verdict
Yes, with care

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

What to watch

What works

Water side by side

55°60°65°70°75°80°85°90°Both: 70–77°Koi 59–77°Platy 70–80°
The green band is the temperature range both can live in.
456789Both: 7–8.2Koi 7–8.5Platy 7–8.2
The green band is the pH both tolerate.

Size to scale

Koi · 24 inPlaty · 2.5 in0"6"12"18"24"
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

KoiPlaty
Temperature59–77 °F70–80 °F
pH7–8.57–8.2
Adult size24.0 in2.5 in
Minimum tankPond10 gal
TemperamentPeacefulPeaceful
Swims atAll levelsMiddle
GroupGroups of 3+Groups of 3+
DietOmnivoreOmnivore

Better tank mates for koi

All koi tank mates

Better tank mates for platies

All platy tank mates

Questions

Can koi live with platies?

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

What temperature suits both koi and platies?

70–77 °F. Koi need 59–77 °F, platies need 70–80 °F.

What size tank do koi and platies need together?

A pond. Koi outgrow indoor tanks.