Species Overview
The Least Rasbora (Boraras urophthalmoides) is proof that some of the most captivating aquarium fish are also among the smallest. Rarely exceeding an inch in length, this peaceful nano species brings subtle beauty, constant movement, and fascinating schooling behavior to planted aquariums. Their delicate bronze-to-copper coloration and active nature make them a favorite among aquarists who appreciate natural aquarium displays over flashy showpieces.
When maintained in proper groups, Least Rasboras spend much of their day moving together through plants and open water, creating a sense of life and activity that makes an aquarium feel truly established. Their small size allows them to utilize every corner of the aquarium without crowding larger fish.
| Key Features | Details |
|---|---|
| Size | Up to 1 inch (2.5 cm) |
| Coloration | Brick red to copper bronze |
| Behavior | Peaceful, active, schooling |
| Water Conditions | Soft, slightly acidic to neutral (pH 6.0–7.0), warm (72–78°F) |
| Group Size | 6 or more for natural behavior |
FAQ
What is the ideal group size for Least Rasboras?
Least Rasboras should be kept in groups of at least six to exhibit natural schooling behavior and maintain their active, peaceful demeanor.
Do Least Rasboras require special water conditions?
Yes, they thrive in soft, slightly acidic to neutral water with a pH between 6.0 and 7.0 and temperatures between 72–78°F (22–26°C).
Can Least Rasboras coexist with other small fish?
They are generally compatible with other small, non-aggressive species, but should not be kept with very active or predatory fish.
Irene Graham –
I’ve had these rasboras for three months now and they’re incredibly active. They move through the plants constantly, adding a lot of life to my tank. The color is subtle but beautiful, and they don’t stress other fish. I keep them in a group of six and they seem happy and healthy.
Ava Chapman –
These fish are small but make a big difference in the tank’s dynamics. I noticed they form tight schools and stay active throughout the day. The water parameters are easy to maintain, and they don’t require much space. A great choice for a planted tank.
Cameron Davies –
The coloration is exactly as described—copper-bronze and very natural. They’re peaceful and don’t chase or jump around. I love how they interact with the plants and create a sense of movement. Perfect for a low-maintenance, natural-looking setup.