Can firemouth cichlids live with harlequin rasboras?

Verdict
Yes

Yes, firemouth cichlids and harlequin rasboras can live together. Both are fine at 75–80°F. Plan on at least 30 gal.

Firemouth cichlidFiremouth cichlid75–86°F · pH 6.5–8 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: 75–80°Firemouth cichlid 75–86°Harlequin rasbora 72–80°
The green band is the temperature range both can live in.
456789Both: 6.5–7.5Firemouth cichlid 6.5–8Harlequin rasbora 6–7.5
The green band is the pH both tolerate.

Size to scale

Firemouth cichlid · 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

Firemouth cichlidHarlequin rasbora
Temperature75–86 °F72–80 °F
pH6.5–86–7.5
Adult size6.0 in2.0 in
Minimum tank30 gal10 gal
TemperamentSemi-aggressivePeaceful
Swims atBottomMiddle
GroupAlone or in pairsGroups of 6+
DietOmnivoreOmnivore

Better tank mates for firemouth cichlids

All firemouth cichlid tank mates

Better tank mates for harlequin rasboras

All harlequin rasbora tank mates

Questions

Can firemouth cichlids live with harlequin rasboras?

Yes, firemouth cichlids and harlequin rasboras can live together. Both are fine at 75–80°F. Plan on at least 30 gal.

What temperature suits both firemouth cichlids and harlequin rasboras?

75–80 °F. Firemouth cichlids need 75–86 °F, harlequin rasboras need 72–80 °F.

What size tank do firemouth cichlids and harlequin rasboras need together?

At least 30 gal, set by the firemouth cichlid. Add space for each extra fish.