Can apistogramma live with harlequin rasboras?

Verdict
Yes

Yes. Apistogramma and harlequin rasboras make a good pair. Both are fine at 75–80°F. Plan on at least 20 gal.

ApistogrammaApistogramma75–84°F · pH 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: 75–80°Apistogramma 75–84°Harlequin rasbora 72–80°
The green band is the temperature range both can live in.
456789Both: 6–7Apistogramma 5–7Harlequin rasbora 6–7.5
The green band is the pH both tolerate.

Size to scale

Apistogramma · 3 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

ApistogrammaHarlequin rasbora
Temperature75–84 °F72–80 °F
pH5–76–7.5
Adult size3.0 in2.0 in
Minimum tank20 gal10 gal
TemperamentSemi-aggressivePeaceful
Swims atBottomMiddle
GroupAlone or in pairsGroups of 6+
DietCarnivoreOmnivore

Better tank mates for apistogramma

All apistogramma tank mates

Better tank mates for harlequin rasboras

All harlequin rasbora tank mates

Questions

Can apistogramma live with harlequin rasboras?

Yes. Apistogramma and harlequin rasboras make a good pair. Both are fine at 75–80°F. Plan on at least 20 gal.

What temperature suits both apistogramma and harlequin rasboras?

75–80 °F. Apistogramma need 75–84 °F, harlequin rasboras need 72–80 °F.

What size tank do apistogramma and harlequin rasboras need together?

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