Can congo tetras live with cardinal tetras?

Verdict
Yes

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

Congo tetraCongo tetra73–82°F · pH 6–7.5 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: 76–82°Congo tetra 73–82°Cardinal tetra 76–84°
The green band is the temperature range both can live in.
456789Both: 6–7Congo tetra 6–7.5Cardinal tetra 4.6–7
The green band is the pH both tolerate.

Size to scale

Congo tetra · 3 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

Congo tetraCardinal tetra
Temperature73–82 °F76–84 °F
pH6–7.54.6–7
Adult size3.0 in2.0 in
Minimum tank30 gal20 gal
TemperamentPeacefulPeaceful
Swims atMiddleMiddle
GroupGroups of 6+Groups of 6+
DietOmnivoreOmnivore

Better tank mates for congo tetras

All congo tetra tank mates

Better tank mates for cardinal tetras

All cardinal tetra tank mates

Questions

Can congo tetras live with cardinal tetras?

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

What temperature suits both congo tetras and cardinal tetras?

76–82 °F. Congo tetras need 73–82 °F, cardinal tetras need 76–84 °F.

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

At least 30 gal, set by the congo tetra. Add space for each extra fish.