Can red tail sharks live with killifish?

Verdict
Yes

Yes. Red tail sharks and killifish make a good pair. Both are fine at 72–77°F. Plan on at least 55 gal.

Red tail sharkRed tail shark72–79°F · pH 6.5–7.5 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°Red tail shark 72–79°Killifish 70–77°
The green band is the temperature range both can live in.
456789Both: 6.5–7Red tail shark 6.5–7.5Killifish 5.5–7
The green band is the pH both tolerate.

Size to scale

Red tail shark · 5 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

Red tail sharkKillifish
Temperature72–79 °F70–77 °F
pH6.5–7.55.5–7
Adult size5.0 in2.5 in
Minimum tank55 gal10 gal
TemperamentSemi-aggressivePeaceful
Swims atBottomTop
GroupOne per tankAlone or in pairs
DietOmnivoreCarnivore

Better tank mates for red tail sharks

All red tail shark tank mates

Better tank mates for killifish

All killifish tank mates

Questions

Can red tail sharks live with killifish?

Yes. Red tail sharks and killifish make a good pair. Both are fine at 72–77°F. Plan on at least 55 gal.

What temperature suits both red tail sharks and killifish?

72–77 °F. Red tail sharks need 72–79 °F, killifish need 70–77 °F.

What size tank do red tail sharks and killifish need together?

At least 55 gal, set by the red tail shark. Add space for each extra fish.