Brilliant Rasbora

The Brilliant Rasbora is a medium-sized, elegant rasbora native to the blackwater rivers and streams of the Malay Peninsula and Borneo. It grows to approximately 9 cm, making it one of the larger rasboras encountered in the hobby, and displays a clean, streamlined body with a distinctive bold dark lateral stripe running from the snout through the eye to the caudal peduncle. In good lighting conditions, particularly against a dark substrate, the flanks reveal iridescent blue-green and golden highlights that justify its common name. The species is found in soft, acidic, tannin-stained waters associated with peat swamp forests and lowland rainforest streams. In the aquarium it shows best coloration and most natural behavior in conditions that replicate this environment: dark substrate, driftwood, dried leaves, minimal hardness, and slightly acidic pH. The Brilliant Rasbora is entirely peaceful and poses no threat to tankmates of any size. A school of six or more produces a cohesive, elegant display. It accepts a broad range of water conditions within its tolerance range and is not particularly demanding once established. An omnivore, it readily consumes most standard aquarium foods. This species is a rewarding choice for planted tank and blackwater biotope enthusiasts.

Tank Setup A minimum of 100 liters for a school of six or more. The larger footprint accommodates the 9 cm adult size and schooling nature of this species. Use dark substrate such as black sand. Add driftwood, catappa leaves, and dried botanicals to replicate the blackwater environment and naturally tint the water. Dense planting with shade-tolerant species such as Java fern, Bolbitis, or Cryptocoryne completes the setup.

Water Parameters Maintain pH between 5.5 and 7.5, ideally toward the acidic end for best coloration. Temperature of 22–28°C is appropriate. No specific hardness requirements, but soft, low-conductivity water is ideal and mirrors the natural blackwater habitat. Perform weekly water changes of 20–25%, using soft or reverse-osmosis water if tap water is hard.

Feeding An adaptable omnivore. Offer quality flake or small pellets as a staple, supplemented with live or frozen foods such as daphnia, brine shrimp, and bloodworm. Feed two to three times daily. A varied diet maintains the best coloration and condition in this species.

Tankmates Excellent community species. Compatible with other rasboras, small to medium peaceful danios, tetras, dwarf gouramis, corydoras, and peaceful loaches. Ideal companions for a blackwater biotope include Harlequin Rasboras, other Rasbora species, and dwarf cichlids such as Apistogramma.

Health and Maintenance Generally hardy when water quality and parameters are maintained. Sensitive to hard, alkaline water conditions — if tap water is hard, use RO or rainwater to achieve the correct chemistry. Monitor for ich and skin flukes. Perform consistent weekly water changes.