Overview
The Harlequin Rasbora is a small, gleaming fish from the warm, soft, tea-colored streams of Malaysia, Thailand, and Singapore in Southeast Asia. Its body glows a warm coppery pink, and its most famous feature is a bold black patch shaped like a triangle or a slice of pie on the back half of its body. That mark is how you can tell it apart from other rasboras at a glance.
These fish are peaceful, hardy, and love company. In a school of six or more, they swim together in tight, shimmering groups that catch the light beautifully. They are one of the classic community-tank fish, easy to feed and gentle with tankmates, which has made them a favorite in home aquariums for over a hundred years.
| Care level | Easy |
| Adult size | 2 in (5 cm) |
| Lifespan | 5-8 years |
| Temperament | Peaceful |
| Min. tank | 15 gallons (57 L) |
| Temperature | 72-80 F (22-27 C) |
| pH | 6.0-7.5 |
| Diet | Omnivore |
| Schooling | Yes, keep 6 or more |
The black triangle
The dark, triangle-shaped patch on the back half of the body is the Harlequin Rasbora's trademark. No other common rasbora wears quite the same mark.
A shimmering school
Harlequins love to swim in groups. A school of six or more moves together like a flock of birds, and their pink bodies flash as they turn.
Soft blackwater streams
In the wild they live in soft, slightly acidic water stained brown by fallen leaves. A gently planted tank with subdued light shows off their colors best.
A community classic
Calm and gentle, Harlequin Rasboras get along with almost every peaceful fish. They have been beloved aquarium fish since the early 1900s.
Fun facts
- The Harlequin Rasbora is named after the colorful diamond patterns of a harlequin costume.
- Its black triangle patch is the easiest way to tell it from similar rasboras.
- They lay their eggs on the underside of broad leaves, which is unusual for a rasbora.
- These fish come from the soft, acidic blackwater streams of Southeast Asia.
- They have been popular aquarium fish for more than a century.
Frequently asked questions
How many Harlequin Rasboras should I keep?
Keep at least six. They are schooling fish that feel safe and look their best in a group.
Are they good for beginners?
Yes. They are hardy, peaceful, and easy to care for, making them an excellent first community fish.
What fish can live with them?
Other peaceful small fish like tetras, other rasboras, and gentle bottom dwellers make great tankmates.
What do they eat?
They are omnivores that eat flakes, tiny pellets, and small treats like daphnia and brine shrimp.
