The Dwarf Rasbora is a tiny, vibrant schooling fish with striking red coloring, a perfect choice for planted nano aquariums with peaceful tankmates.
Overview
Boraras maculatus is one of the smallest members of the Cyprinidae family, reaching just 1.5–2 cm in length. In the wild, this fish inhabits slow-moving streams, peat swamps, and flooded forest areas of the Malay Peninsula, Sumatra, and Singapore. The water in these biotopes is typically soft, acidic, and stained a characteristic tea color by tannins.
The body of Boraras maculatus is semi-transparent with a rich reddish-orange hue and several striking dark spots — one large spot near the base of the tail and two smaller ones along the flank. These distinctive spots are what give the fish its name. Unlike its close relative, Boraras brigittae, the Dwarf Rasbora has less intensely red coloration, but its spot pattern is unique and easily recognizable.
Lifespan in the aquarium is 3–4 years with proper care. Thanks to its tiny size and peaceful temperament, Boraras maculatus has become a favorite among nano tank enthusiasts worldwide.
Tank Requirements
A tank of at least 20 liters is suitable for a school of 8–12 individuals, though a 30–40 liter aquarium will provide significantly more comfort. Water parameters should be maintained within the following ranges: temperature 22–28 °C, pH 5.0–7.0, and general hardness (GH) 2–12 dGH.
The aquascape should closely mimic the natural biotope. Use dark substrate, abundant vegetation — Java moss, Cryptocoryne, Bucephalandra — and floating plants (water lettuce, Riccia, Salvinia) to diffuse light. Driftwood and leaf litter (Indian almond or oak leaves) will not only provide hiding spots but also tint the water with tannins, which is beneficial for these fish.
Flow should be minimal — use a sponge filter or an internal filter with a flow diffuser. Strong currents stress these small fish and drain their energy.
Feeding and Diet
In their natural habitat, Boraras maculatus feeds on zooplankton, small crustaceans, and insect larvae. In the aquarium, high-quality micro-pellets and crushed flakes can form the staple diet, but live or frozen foods are essential for maintaining health and vibrant coloration: baby brine shrimp, daphnia, cyclops, micro-worms, and grindal worms.
Feed twice daily in small portions that the fish can consume within 1–2 minutes. Keep in mind that Boraras have very small mouths — all foods must be appropriately sized. Always remove uneaten food promptly to prevent water quality deterioration in a small tank.
Care and Maintenance
Despite their tiny size, Boraras maculatus is a fairly hardy fish with a care level suitable for beginners. The key rule is parameter stability. Regular water changes (15–20% of volume weekly) are essential for maintaining cleanliness. When performing water changes, ensure the fresh water matches the temperature and parameters of the tank water.
Test ammonia, nitrite, and nitrate levels weekly. In a mature, planted tank with moderate bioload, problems rarely arise. Make sure the aquarium is tightly covered with a lid or cover glass — these small fish can jump through the slightest gaps.
Avoid sudden fluctuations in temperature and pH — this is especially critical for Boraras due to their small size and sensitive metabolism.
Compatibility
Boraras maculatus is a schooling fish that should be kept in groups of at least 8–10 individuals. In a school, the fish behave more confidently, display natural behaviors and vivid coloration, and males engage in spectacular yet harmless sparring displays.
Ideal tankmates include other micro fish: Boraras brigittae, Boraras merah, Celestial Pearl Danio, Hengel's Rasbora, and small tetras such as the Ember Tetra. Dwarf shrimp (Neocaridina, Caridina) and small snails also make excellent companions.
It is absolutely not recommended to keep them with large or aggressive fish — any tankmate capable of fitting a Boraras in its mouth poses a lethal threat. Avoid cichlids, large barbs, and predatory catfish.
Breeding
Breeding Boraras maculatus in the aquarium is possible, though it requires specific conditions and patience. Prepare a separate breeding tank of 5–10 liters with soft, acidic water (pH 5.0–6.5, GH 1–4) and a temperature of 26–28 °C. Place fine-leaved plants or synthetic spawning mops on the bottom, along with a mesh grid to protect the eggs from being eaten.
The female scatters fine eggs among the plants, after which the adults should be removed immediately. The eggs incubate for 24–36 hours, and after another 2–3 days the fry become free-swimming. During the first days, feed them infusoria and liquid fry food, then transition to baby brine shrimp after 7–10 days.
Fry grow slowly, and during the first weeks they require clean water with frequent but minimal water changes. Lighting in the breeding tank should be subdued — bright light can damage both eggs and larvae.