The Black Harlequin Rasbora is a popular aquarium fish. These fish have a black, triangle-shaped patch starting near the dorsal fin, and a mostly black body.
The males patch is slightly rounded at the bottom with an extended tip, while the females is straight. Females are larger than males.
Harlequins require an established planted aquarium. They should be kept in schools of 8-10 and in an aquarium with other small, peaceful fish.
Rasbora heteromorpha like to spawn on the undersides of broad-leaved plants.
A breeding tank with shallow, warm, acidic, soft water with broad-leaved plants should be set up. Pair a young female (9-12 months old) with a two-year old male and feed them live foods.
After spawning, remove the parents and keep the aquarium dark until the eggs hatch (after about 24 hours). Feed the fry infusoria.
An omnivore, Black Harlequin Rasboras do well on a diet of prepared flake food, as well as freeze-dried bloodworms and tubifex.