Harlequin Rasbora (Trigonostigma heteromorpha)
A small, energetic fish native to Malaysia, Thailand, and Singapore, the Harlequin Rasbora is known for its hardiness and peaceful nature.
Perfect for community tanks, these fish thrive when kept in groups.
| Specification | Detail |
|---|---|
| Minimum Tank Size | 10 Gallons |
| Maximum Fish Size | 1 inch |
| Water Temperature | 75F – 85F |
| Ideal pH | 6.0 – 7.5 |
| Water Hardness | 2 – 15 dGH |
| Temperament | Peaceful, schooling species. May be timid in small schools. |
Unless experienced with fish-in cycling, we always suggest cycling an aquarium before adding fish. Adding fish to a fresh, un-cycled aquarium can be fatal. We offer free water testing at our physical location and advice via email or phone.
FAQ
What is the ideal water temperature for Harlequin Rasbora?
The ideal water temperature is between 75F and 85F.
How many Harlequin Rasbora should I keep together?
They are schooling fish and should be kept in groups of at least 6 to ensure their comfort and well-being.
Is Harlequin Rasbora suitable for beginners?
Yes, they are hardy and peaceful, making them a good choice for beginners. However, it’s important to cycle the tank before adding them.

Frank Forsyth –
I bought these fish for my 10-gallon community tank. They are active and colorful, and they seem to get along well with my other fish. I made sure to cycle the tank first, and it made a big difference. They’re easy to care for and stay healthy.
Leonard Peake –
The Harlequin Rasbora are lively and add a nice touch to the tank. I kept them in a group of six and they don’t seem stressed. Water parameters were stable after cycling, and they’ve been thriving for over two months.
Jessica Cameron –
Great little fish. They’re peaceful and don’t bother other species. I followed the advice to cycle the tank first, and it worked perfectly. They’ve grown to about 1 inch and are still active.