Dwarf Rasbora (Boraras maculatus)

Boraras maculatus, the Dwarf Rasbora or Spotted Rasbora, is one of four recognised Boraras species — a genus of micro-cyprinids from Southeast Asian blackwater habitats characterised by their brilliant colours and tiny size. At approximately 2.5 cm adult size, B. maculatus is a true nano fish that requires an appropriately small-scale setup.

The colouration is attractive: a vivid orange to salmon-red body with distinctive dark spots — typically two to three along the lateral midline and additional marks at the dorsal fin base and caudal peduncle. This spotted pattern distinguishes it from the striped Chili Rasbora (B. brigittae) and the single-spotted Strawberry Rasbora (B. naevus).

Native to the blackwater peat swamps and forest streams of Malaysia, Sumatra, Thailand, and neighbouring countries, B. maculatus inhabits extremely soft, highly acidic, tannin-rich water with very little mineral content. These conditions are essential for its health and optimal colouration in the aquarium — hard, alkaline water causes colour loss and health decline.

The Boraras genus as a whole are popular 'nano fish' for the planted tank hobby, valued for their combination of vivid colour, tiny size, and suitability for small aquariums. They create beautiful micro-scale schooling displays when kept in appropriately large numbers (10+) in well-established, densely planted nano setups.

Tank Setup: A 20–30 litre nano planted aquarium. Dark substrate, dense fine-leaved planting, Indian almond leaves and driftwood for tannins, very gentle sponge filtration, and near-still water movement. Must be a well-established, stable system before introduction.

Water Parameters: Temperature 23–28°C; pH 4.0–6.5; GH 1–5 °dH; KH 0–2 °dH. Extremely soft, acidic blackwater conditions. Use RO water conditioned with Indian almond or catappa leaves, or peat. Standard tap water unsuitable.

Feeding: Micro-omnivore. Baby brine shrimp, Daphnia nauplii, micro worms, powdered fry food. Very small mouths — all food must be micro-sized. Feed twice daily.

Tank Mates: Only other Boraras species or compatible nano fish in identical water chemistry. Dwarf shrimp that tolerate soft acidic water (Crystal Red Shrimp — Caridina). No fish larger than 3 cm.

Behaviour: Loose schooling in groups of 10+. Very peaceful. Male displays with vivid colour intensification toward females. No aggression toward any species.

Health: Sensitive to all chemistry deviations. Very small size = rapid deterioration in suboptimal conditions. Precise, stable water chemistry is the single most important care factor.