Can ember tetras live with congo tetras?

Verdict
Yes

Yes. Ember tetras and congo tetras make a good pair. Both are fine at 73–82°F. Plan on at least 30 gal.

Ember tetraEmber tetra73–84°F · pH 5.5–7 Congo tetraCongo tetra73–82°F · pH 6–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 73–82°Ember tetra 73–84°Congo tetra 73–82°
The green band is the temperature range both can live in.
456789Both: 6–7Ember tetra 5.5–7Congo tetra 6–7.5
The green band is the pH both tolerate.

Size to scale

Ember tetra · 0.8 inCongo tetra · 3 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 tetraCongo tetra
Temperature73–84 °F73–82 °F
pH5.5–76–7.5
Adult size0.8 in3.0 in
Minimum tank5 gal30 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 congo tetras

All congo tetra tank mates

Questions

Can ember tetras live with congo tetras?

Yes. Ember tetras and congo tetras make a good pair. Both are fine at 73–82°F. Plan on at least 30 gal.

What temperature suits both ember tetras and congo tetras?

73–82 °F. Ember tetras need 73–84 °F, congo tetras need 73–82 °F.

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

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