Can guppies live with killifish?

Verdict
Yes

Yes, guppies and killifish can live together. Both are fine at 72–77°F. Plan on at least 10 gal.

GuppyGuppy72–82°F · pH 6.8–7.8 KillifishKillifish70–77°F · pH 5.5–7

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 72–77°Guppy 72–82°Killifish 70–77°
The green band is the temperature range both can live in.
456789Both: 6.8–7Guppy 6.8–7.8Killifish 5.5–7
The green band is the pH both tolerate.

Size to scale

Guppy · 2 inKillifish · 2.5 in0"1"2"3"4"5"6"
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

GuppyKillifish
Temperature72–82 °F70–77 °F
pH6.8–7.85.5–7
Adult size2.0 in2.5 in
Minimum tank10 gal10 gal
TemperamentPeacefulPeaceful
Swims atTopTop
GroupGroups of 3+Alone or in pairs
DietOmnivoreCarnivore

Better tank mates for guppies

All guppy tank mates

Better tank mates for killifish

All killifish tank mates

Questions

Can guppies live with killifish?

Yes, guppies and killifish can live together. Both are fine at 72–77°F. Plan on at least 10 gal.

What temperature suits both guppies and killifish?

72–77 °F. Guppies need 72–82 °F, killifish need 70–77 °F.

What size tank do guppies and killifish need together?

At least 10 gal, set by the guppy. Add space for each extra fish.