Can harlequin rasboras live with serpae tetras?

Verdict
Yes

Yes, harlequin rasboras and serpae tetras can live together. Both are fine at 72–79°F. Plan on at least 20 gal.

Harlequin rasboraHarlequin rasbora72–80°F · pH 6–7.5 Serpae tetraSerpae tetra72–79°F · pH 6–7.5

Why it works

Water side by side

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

Size to scale

Harlequin rasbora · 2 inSerpae tetra · 1.75 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 rasboraSerpae tetra
Temperature72–80 °F72–79 °F
pH6–7.56–7.5
Adult size2.0 in1.75 in
Minimum tank10 gal20 gal
TemperamentPeacefulSemi-aggressive
Swims atMiddleMiddle
GroupGroups of 6+Groups of 6+
DietOmnivoreOmnivore

Better tank mates for harlequin rasboras

All harlequin rasbora tank mates

Better tank mates for serpae tetras

All serpae tetra tank mates

Questions

Can harlequin rasboras live with serpae tetras?

Yes, harlequin rasboras and serpae tetras can live together. Both are fine at 72–79°F. Plan on at least 20 gal.

What temperature suits both harlequin rasboras and serpae tetras?

72–79 °F. Harlequin rasboras need 72–80 °F, serpae tetras need 72–79 °F.

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

At least 20 gal, set by the serpae tetra. Add space for each extra fish.