Can platies live with harlequin rasboras?

Verdict
Yes

Yes. Platies and harlequin rasboras get along in the same tank. Both are fine at 72–80°F. Plan on at least 10 gal.

PlatyPlaty70–80°F · pH 7–8.2 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: 72–80°Platy 70–80°Harlequin rasbora 72–80°
The green band is the temperature range both can live in.
456789Both: 7–7.5Platy 7–8.2Harlequin rasbora 6–7.5
The green band is the pH both tolerate.

Size to scale

Platy · 2.5 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

PlatyHarlequin rasbora
Temperature70–80 °F72–80 °F
pH7–8.26–7.5
Adult size2.5 in2.0 in
Minimum tank10 gal10 gal
TemperamentPeacefulPeaceful
Swims atMiddleMiddle
GroupGroups of 3+Groups of 6+
DietOmnivoreOmnivore

Better tank mates for platies

All platy tank mates

Better tank mates for harlequin rasboras

All harlequin rasbora tank mates

Questions

Can platies live with harlequin rasboras?

Yes. Platies and harlequin rasboras get along in the same tank. Both are fine at 72–80°F. Plan on at least 10 gal.

What temperature suits both platies and harlequin rasboras?

72–80 °F. Platies need 70–80 °F, harlequin rasboras need 72–80 °F.

What size tank do platies and harlequin rasboras need together?

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