Can guppies live with harlequin rasboras?

Verdict
Yes

Yes, guppies and harlequin rasboras can live together. Both are fine at 72–80°F. Plan on at least 10 gal.

GuppyGuppy72–82°F · pH 6.8–7.8 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°Guppy 72–82°Harlequin rasbora 72–80°
The green band is the temperature range both can live in.
456789Both: 6.8–7.5Guppy 6.8–7.8Harlequin rasbora 6–7.5
The green band is the pH both tolerate.

Size to scale

Guppy · 2 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

GuppyHarlequin rasbora
Temperature72–82 °F72–80 °F
pH6.8–7.86–7.5
Adult size2.0 in2.0 in
Minimum tank10 gal10 gal
TemperamentPeacefulPeaceful
Swims atTopMiddle
GroupGroups of 3+Groups of 6+
DietOmnivoreOmnivore

Better tank mates for guppies

All guppy tank mates

Better tank mates for harlequin rasboras

All harlequin rasbora tank mates

Questions

Can guppies live with harlequin rasboras?

Yes, guppies and harlequin rasboras can live together. Both are fine at 72–80°F. Plan on at least 10 gal.

What temperature suits both guppies and harlequin rasboras?

72–80 °F. Guppies need 72–82 °F, harlequin rasboras need 72–80 °F.

What size tank do guppies and harlequin rasboras need together?

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