Black Harlequin Rasbora
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 purple to black body. The male’s patch is slightly rounded at the bottom with an extended tip, while the female’s is straight. Females are larger than males.
Harlequins require an established planted aquarium. They should be kept in schools of six or more 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.
| Feature | Detail |
|---|---|
| Body Color | Purple to black |
| Distinctive Mark | Black triangle near dorsal fin |
| Sex Difference | Males have rounded tip; females have straight patch; females are larger |
| Group Size | 6 or more fish |
| Water Conditions | Shallow, warm, acidic, soft water with broad-leaved plants |
FAQ
What is the difference between male and female Black Harlequin Rasbora?
The male has a slightly rounded triangle patch with an extended tip near the dorsal fin, while the female has a straight patch. Females are also larger in size than males.
How many fish should I keep in a tank?
Keep at least six fish together in a school to ensure their well-being and natural behavior.
What kind of water conditions do they prefer?
They thrive in shallow, warm, acidic, soft water with broad-leaved plants for spawning and shelter.
Trevor Kelly –
The Black Harlequin Rasbora adds vibrant color to my planted tank. I kept them in a group of six and they swim actively. The black triangle pattern is striking and they seem to enjoy the plants. Spawning was successful after setting up a breeding tank with broad-leaved plants and live food.
Alan Parr –
These fish are peaceful and fit well with other small community species. I noticed the males and females differ slightly in the shape of their black patches. They do need a mature planted tank, but once established, they are very active and attractive.
Carol Thomson –
I paired a young female with a two-year-old male and observed spawning on the undersides of java fern. After spawning, I removed the parents and kept the tank dark. The fry developed well and I’m happy with the result.