Can ember tetras live with harlequin rasboras?

Verdict
Yes

Yes. Ember tetras and harlequin rasboras make a good pair. Both are fine at 73–80°F. Plan on at least 10 gal.

Ember tetraEmber tetra73–84°F · pH 5.5–7 Harlequin rasboraHarlequin rasbora72–80°F · pH 6–7.5

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 73–80°Ember tetra 73–84°Harlequin rasbora 72–80°
The green band is the temperature range both can live in.
456789Both: 6–7Ember tetra 5.5–7Harlequin rasbora 6–7.5
The green band is the pH both tolerate.

Size to scale

Ember tetra · 0.8 inHarlequin rasbora · 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 tetraHarlequin rasbora
Temperature73–84 °F72–80 °F
pH5.5–76–7.5
Adult size0.8 in2.0 in
Minimum tank5 gal10 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 harlequin rasboras

All harlequin rasbora tank mates

Questions

Can ember tetras live with harlequin rasboras?

Yes. Ember tetras and harlequin rasboras make a good pair. Both are fine at 73–80°F. Plan on at least 10 gal.

What temperature suits both ember tetras and harlequin rasboras?

73–80 °F. Ember tetras need 73–84 °F, harlequin rasboras need 72–80 °F.

What size tank do ember tetras and harlequin rasboras need together?

At least 10 gal, set by the harlequin rasbora. Add space for each extra fish.