Can goldfish live with koi?

Verdict
Yes

Yes. Goldfish and koi make a good pair. Both are fine at 60–74°F. Plan on at least Pond.

GoldfishGoldfish60–74°F · pH 7–8 KoiKoi59–77°F · pH 7–8.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 60–74°Goldfish 60–74°Koi 59–77°
The green band is the temperature range both can live in.
456789Both: 7–8Goldfish 7–8Koi 7–8.5
The green band is the pH both tolerate.

Size to scale

Goldfish · 10 inKoi · 24 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

GoldfishKoi
Temperature60–74 °F59–77 °F
pH7–87–8.5
Adult size10.0 in24.0 in
Minimum tank40 galPond
TemperamentPeacefulPeaceful
Swims atAll levelsAll levels
GroupAlone or in pairsGroups of 3+
DietOmnivoreOmnivore

Better tank mates for goldfish

All goldfish tank mates

Better tank mates for koi

All koi tank mates

Questions

Can goldfish live with koi?

Yes. Goldfish and koi make a good pair. Both are fine at 60–74°F. Plan on at least Pond.

What temperature suits both goldfish and koi?

60–74 °F. Goldfish need 60–74 °F, koi need 59–77 °F.

What size tank do goldfish and koi need together?

A pond. Koi outgrow indoor tanks.