Can killifish live with dwarf neon rainbowfish?

Verdict
Yes

Yes. Killifish and dwarf neon rainbowfish make a good pair. Both are fine at 75–77°F. Plan on at least 20 gal.

KillifishKillifish70–77°F · pH 5.5–7 Dwarf neon rainbowfishDwarf neon rainbowfish75–82°F · pH 6.5–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 75–77°Killifish 70–77°Dwarf neon rainbowfish 75–82°
The green band is the temperature range both can live in.
456789Both: 6.5–7Killifish 5.5–7Dwarf neon rainbowfish 6.5–7.5
The green band is the pH both tolerate.

Size to scale

Killifish · 2.5 inDwarf neon rainbowfish · 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

KillifishDwarf neon rainbowfish
Temperature70–77 °F75–82 °F
pH5.5–76.5–7.5
Adult size2.5 in2.5 in
Minimum tank10 gal20 gal
TemperamentPeacefulPeaceful
Swims atTopMiddle
GroupAlone or in pairsGroups of 6+
DietCarnivoreOmnivore

Better tank mates for killifish

All killifish tank mates

Better tank mates for dwarf neon rainbowfish

All dwarf neon rainbowfish tank mates

Questions

Can killifish live with dwarf neon rainbowfish?

Yes. Killifish and dwarf neon rainbowfish make a good pair. Both are fine at 75–77°F. Plan on at least 20 gal.

What temperature suits both killifish and dwarf neon rainbowfish?

75–77 °F. Killifish need 70–77 °F, dwarf neon rainbowfish need 75–82 °F.

What size tank do killifish and dwarf neon rainbowfish need together?

At least 20 gal, set by the dwarf neon rainbowfish. Add space for each extra fish.