Can cardinal tetras live with electric blue acaras?

Verdict
Yes

Yes, cardinal tetras and electric blue acaras can live together. Both are fine at 76–82°F. Plan on at least 30 gal.

Cardinal tetraCardinal tetra76–84°F · pH 4.6–7 Electric blue acaraElectric blue acara72–82°F · pH 6.5–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 76–82°Cardinal tetra 76–84°Electric blue acara 72–82°
The green band is the temperature range both can live in.
456789Both: 6.5–7Cardinal tetra 4.6–7Electric blue acara 6.5–7.5
The green band is the pH both tolerate.

Size to scale

Cardinal tetra · 2 inElectric blue acara · 6 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 tetraElectric blue acara
Temperature76–84 °F72–82 °F
pH4.6–76.5–7.5
Adult size2.0 in6.0 in
Minimum tank20 gal30 gal
TemperamentPeacefulSemi-aggressive
Swims atMiddleMiddle
GroupGroups of 6+Alone or in pairs
DietOmnivoreOmnivore

Better tank mates for cardinal tetras

All cardinal tetra tank mates

Better tank mates for electric blue acaras

All electric blue acara tank mates

Questions

Can cardinal tetras live with electric blue acaras?

Yes, cardinal tetras and electric blue acaras can live together. Both are fine at 76–82°F. Plan on at least 30 gal.

What temperature suits both cardinal tetras and electric blue acaras?

76–82 °F. Cardinal tetras need 76–84 °F, electric blue acaras need 72–82 °F.

What size tank do cardinal tetras and electric blue acaras need together?

At least 30 gal, set by the electric blue acara. Add space for each extra fish.