Harlequin Rasbora Identification Guide
Recognize a harlequin rasbora by the bold black triangular wedge covering the rear half of its coppery-orange body.
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Key identification features
- Small, deep-bodied, laterally compressed silhouette compared to slimmer rasbora relatives
- Coppery-orange to pinkish-red overall body color
- Distinctive black, wedge- or triangle-shaped patch covering roughly the rear half of the body, from mid-flank back to the caudal peduncle
- The front edge of the black wedge angles sharply forward and comes to a point near the middle of the body
- Short, rounded fins with little additional patterning
- Small size, typically 4-5 cm
Common look-alikes
- Lambchop rasbora (Espei rasbora): a very similar black wedge, but its front edge is more rounded and less sharply angled, and the body is slightly slimmer overall
- Glowlight rasbora: lacks the black wedge entirely, instead showing a thin, glowing orange-red horizontal line along the body
- Emerald dwarf rasbora: much smaller and lacks any large dark patch, showing scattered small spots instead
Where you'll see one
Harlequin rasboras are native to slow-moving, acidic blackwater streams, swamps, and peat forests of the Malay Peninsula, Sumatra, and Borneo, where they school in shaded water thick with submerged plants and leaf litter.
Frequently asked questions
How do I tell a harlequin rasbora from a lambchop rasbora?
Look at the front edge of the black body patch: a harlequin rasbora's wedge comes to a sharp forward point, while a lambchop rasbora's patch has a more rounded front edge.
How do I tell a harlequin rasbora from a glowlight rasbora?
A harlequin rasbora has a bold black wedge covering its rear half, which a glowlight rasbora completely lacks, showing only a thin glowing line instead.