Can ember tetras live with cardinal tetras?

Verdict
Yes

Yes, ember tetras and cardinal tetras can live together. Both are fine at 76–84°F. Plan on at least 20 gal.

Ember tetraEmber tetra73–84°F · pH 5.5–7 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: 76–84°Ember tetra 73–84°Cardinal tetra 76–84°
The green band is the temperature range both can live in.
456789Both: 5.5–7Ember tetra 5.5–7Cardinal tetra 4.6–7
The green band is the pH both tolerate.

Size to scale

Ember tetra · 0.8 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

Ember tetraCardinal tetra
Temperature73–84 °F76–84 °F
pH5.5–74.6–7
Adult size0.8 in2.0 in
Minimum tank5 gal20 gal
TemperamentPeacefulPeaceful
Swims atMiddleMiddle
GroupGroups of 6+Groups of 6+
DietOmnivoreOmnivore

Better tank mates for ember tetras

All ember tetra tank mates

Better tank mates for cardinal tetras

All cardinal tetra tank mates

Questions

Can ember tetras live with cardinal tetras?

Yes, ember tetras and cardinal tetras can live together. Both are fine at 76–84°F. Plan on at least 20 gal.

What temperature suits both ember tetras and cardinal tetras?

76–84 °F. Ember tetras need 73–84 °F, cardinal tetras need 76–84 °F.

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

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