Boraras Naevus (Strawberry Rasbora)

Boraras naevus, the Strawberry Rasbora or Spot Rasbora, is a diminutive and enchanting micro rasbora from southern Thailand. At just 2 cm adult size, it is one of the smallest members of the genus Boraras — a group of Southeast Asian micro-cyprinids famous for their vivid colouration and suitability for nano planted aquariums.

The Strawberry Rasbora displays a beautiful pinkish-red to salmon colouration across the body, with a single dark lateral spot (naevus = spot/mole) positioned just behind the pectoral fins. The combination of reddish body and dark spot creates a simple but charming pattern. Males typically display more vivid colouration, especially when in spawning condition.

Like all Boraras species, B. naevus comes from slow-moving, heavily vegetated, tannin-stained blackwater streams and peat swamps in Thailand — habitats with extremely soft, highly acidic water. Replicating these conditions in the aquarium produces the most vivid colouration.

The Strawberry Rasbora is closely related to and often confused with Boraras urophthalmoides and Boraras brigittae (Chili Rasbora). Unlike the Chili Rasbora, which has a lateral stripe, the Strawberry has only the single spot, making identification straightforward.

This species is ideal for nano community tanks with other micro fish, dwarf shrimp, and fine-leaved plants. A group of 15–20 creates a stunning living cloud of colour in the middle water.

Tank Setup: A 20–30 litre nano aquarium is sufficient for 10–15 fish. Use dark substrate, dense fine-leaved planting (Java moss, Rotala, Blyxa), Indian almond leaves for tannins, and gentle sponge filtration. Very low water flow — replicate near-still blackwater conditions.

Water Parameters: Temperature 23–28°C; pH 5.0–6.5; GH 1–6 °dH; KH 1–3 °dH. Soft, acidic blackwater conditions are strongly preferred for vivid colour and health. Use RO or rain water blended with tap if your tap is hard.

Feeding: Micro-omnivore. Feed baby brine shrimp, micro worms, Daphnia nauplii, crushed micro flake, powdered fry food. Mouths are tiny — all food must be micro-sized. Feed twice daily.

Tank Mates: Only the most delicate, smallest species: other Boraras, Least Killifish, Pygmy Corydoras, Sundadanio axelrodi, Neocaridina or Caridina shrimp (note: may eat shrimplets). Avoid any fish larger than 3 cm.

Behaviour: Peaceful micro schooling fish. Groups of 10+ school loosely but exhibit fascinating behaviour. Males court with vivid colour display. Extremely peaceful — never aggressive toward any species.

Health: Sensitive to water quality and chemistry deviations. Avoid hard, alkaline water or elevated nitrates. Very small size means they are susceptible to bacterial infections in suboptimal conditions. Pristine water is key.