Can harlequin rasboras live with black skirt tetras?

Verdict
Yes

Yes. Harlequin rasboras and black skirt tetras make a good pair. Both are fine at 72–80°F. Plan on at least 15 gal.

Harlequin rasboraHarlequin rasbora72–80°F · pH 6–7.5 Black skirt tetraBlack skirt tetra70–80°F · pH 6–7.5

Why it works

Water side by side

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

Size to scale

Harlequin rasbora · 2 inBlack skirt tetra · 2.5 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 rasboraBlack skirt tetra
Temperature72–80 °F70–80 °F
pH6–7.56–7.5
Adult size2.0 in2.5 in
Minimum tank10 gal15 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 black skirt tetras

All black skirt tetra tank mates

Questions

Can harlequin rasboras live with black skirt tetras?

Yes. Harlequin rasboras and black skirt tetras make a good pair. Both are fine at 72–80°F. Plan on at least 15 gal.

What temperature suits both harlequin rasboras and black skirt tetras?

72–80 °F. Harlequin rasboras need 72–80 °F, black skirt tetras need 70–80 °F.

What size tank do harlequin rasboras and black skirt tetras need together?

At least 15 gal, set by the black skirt tetra. Add space for each extra fish.