Can harlequin rasboras live with swordtails?

Verdict
Yes

Yes. Harlequin rasboras and swordtails get along in the same tank. Both are fine at 72–79°F. Plan on at least 30 gal.

Harlequin rasboraHarlequin rasbora72–80°F · pH 6–7.5 SwordtailSwordtail72–79°F · pH 7–8.3

Why it works

Water side by side

55°60°65°70°75°80°85°90°Both: 72–79°Harlequin rasbora 72–80°Swordtail 72–79°
The green band is the temperature range both can live in.
456789Both: 7–7.5Harlequin rasbora 6–7.5Swordtail 7–8.3
The green band is the pH both tolerate.

Size to scale

Harlequin rasbora · 2 inSwordtail · 5 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

Harlequin rasboraSwordtail
Temperature72–80 °F72–79 °F
pH6–7.57–8.3
Adult size2.0 in5.0 in
Minimum tank10 gal30 gal
TemperamentPeacefulSemi-aggressive
Swims atMiddleMiddle
GroupGroups of 6+Groups of 3+
DietOmnivoreOmnivore

Better tank mates for harlequin rasboras

All harlequin rasbora tank mates

Better tank mates for swordtails

All swordtail tank mates

Questions

Can harlequin rasboras live with swordtails?

Yes. Harlequin rasboras and swordtails get along in the same tank. Both are fine at 72–79°F. Plan on at least 30 gal.

What temperature suits both harlequin rasboras and swordtails?

72–79 °F. Harlequin rasboras need 72–80 °F, swordtails need 72–79 °F.

What size tank do harlequin rasboras and swordtails need together?

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