Can cardinal tetras live with killifish?

Verdict
Yes, with care

Yes, with care. Cardinal tetras and killifish can share a tank, but watch one thing. They only share 76–77°F. Keep the heater set there and steady.

Cardinal tetraCardinal tetra76–84°F · pH 4.6–7 KillifishKillifish70–77°F · pH 5.5–7

What to watch

What works

Water side by side

55°60°65°70°75°80°85°90°Both: 76–77°Cardinal tetra 76–84°Killifish 70–77°
The green band is the temperature range both can live in.
456789Both: 5.5–7Cardinal tetra 4.6–7Killifish 5.5–7
The green band is the pH both tolerate.

Size to scale

Cardinal tetra · 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

Cardinal tetraKillifish
Temperature76–84 °F70–77 °F
pH4.6–75.5–7
Adult size2.0 in2.5 in
Minimum tank20 gal10 gal
TemperamentPeacefulPeaceful
Swims atMiddleTop
GroupGroups of 6+Alone or in pairs
DietOmnivoreCarnivore

Better tank mates for cardinal tetras

All cardinal tetra tank mates

Better tank mates for killifish

All killifish tank mates

Questions

Can cardinal tetras live with killifish?

Yes, with care. Cardinal tetras and killifish can share a tank, but watch one thing. They only share 76–77°F. Keep the heater set there and steady.

What temperature suits both cardinal tetras and killifish?

76–77 °F. Cardinal tetras need 76–84 °F, killifish need 70–77 °F.

What size tank do cardinal tetras and killifish need together?

At least 20 gal, set by the cardinal tetra. Add space for each extra fish.