Can neon tetras live with cardinal tetras?

Verdict
Yes

Yes. Neon tetras and cardinal tetras make a good pair. Both are fine at 76–79°F. Plan on at least 20 gal.

Neon tetraNeon tetra72–79°F · pH 6–7 Cardinal tetraCardinal tetra76–84°F · pH 4.6–7

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 76–79°Neon tetra 72–79°Cardinal tetra 76–84°
The green band is the temperature range both can live in.
456789Both: 6–7Neon tetra 6–7Cardinal tetra 4.6–7
The green band is the pH both tolerate.

Size to scale

Neon tetra · 1.5 inCardinal tetra · 2 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

Neon tetraCardinal tetra
Temperature72–79 °F76–84 °F
pH6–74.6–7
Adult size1.5 in2.0 in
Minimum tank10 gal20 gal
TemperamentPeacefulPeaceful
Swims atMiddleMiddle
GroupGroups of 6+Groups of 6+
DietOmnivoreOmnivore

Better tank mates for neon tetras

All neon tetra tank mates

Better tank mates for cardinal tetras

All cardinal tetra tank mates

Questions

Can neon tetras live with cardinal tetras?

Yes. Neon tetras and cardinal tetras make a good pair. Both are fine at 76–79°F. Plan on at least 20 gal.

What temperature suits both neon tetras and cardinal tetras?

76–79 °F. Neon tetras need 72–79 °F, cardinal tetras need 76–84 °F.

What size tank do neon tetras and cardinal tetras need together?

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