Can rainbow sharks live with harlequin rasboras?

Verdict
Yes

Yes. Rainbow sharks and harlequin rasboras make a good pair. Both are fine at 72–80°F. Plan on at least 55 gal.

Rainbow sharkRainbow shark72–80°F · pH 6.5–7.5 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°Rainbow shark 72–80°Harlequin rasbora 72–80°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Rainbow shark 6.5–7.5Harlequin rasbora 6–7.5
The green band is the pH both tolerate.

Size to scale

Rainbow shark · 6 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

Rainbow sharkHarlequin rasbora
Temperature72–80 °F72–80 °F
pH6.5–7.56–7.5
Adult size6.0 in2.0 in
Minimum tank55 gal10 gal
TemperamentSemi-aggressivePeaceful
Swims atBottomMiddle
GroupOne per tankGroups of 6+
DietOmnivoreOmnivore

Better tank mates for rainbow sharks

All rainbow shark tank mates

Better tank mates for harlequin rasboras

All harlequin rasbora tank mates

Questions

Can rainbow sharks live with harlequin rasboras?

Yes. Rainbow sharks and harlequin rasboras make a good pair. Both are fine at 72–80°F. Plan on at least 55 gal.

What temperature suits both rainbow sharks and harlequin rasboras?

72–80 °F. Rainbow sharks need 72–80 °F, harlequin rasboras need 72–80 °F.

What size tank do rainbow sharks and harlequin rasboras need together?

At least 55 gal, set by the rainbow shark. Add space for each extra fish.