Phoenix Rasbora
Boraras merah
The Phoenix Rasbora (Boraras merah) is a minute shoaling fish from the peat-water regions of southern Borneo. It is sometimes sold under the trade name Phoenix Rasbora. Its size may suggest a very small aquarium, yet the species needs a mature, stable setup with suitable water chemistry and enough swimming room for a group. It is peaceful but timid, and can struggle to feed around busy or much larger tank mates. A calm layout, finely sized foods and careful companion choices matter more than keeping it in the smallest possible tank.
Plan your aquarium →At a glance
- Temperature
- 20–28 °C
- pH
- 4.0–6.5
- GH
- 1–5 °dGH
- Aquarium length
- At least 45 cm
- Minimum aquarium volume
- At least 41 L
- Adult size
- At least 2 cm
- Group size
- At least 8–10 individuals
- Temperament
- Peaceful
About this species
The species reaches about 20 mm standard length, which excludes the caudal fin. Red pigmentation is often concentrated around dark spots or markings. The pattern varies, and mature males may appear more striped. This can cause confusion with the related Boraras brigittae. The accepted scientific name is Boraras merah; Rasbora merah is an earlier combination. Do not identify fish solely by a trade name or one colour feature.Natural habitat
The species is known from southern Borneo and was described from the Jelai Bila basin in Central Kalimantan. Specialist accounts describe blackwater streams and rivers associated with peat swamp forest. Leaves, branches and other organic matter stain the water with tannins; it is very soft and acidic, while the forest canopy keeps the light subdued. An aquarium need not copy the habitat exactly, but gentle flow, shaded cover and stable soft conditions suit its origins.Aquarium and layout
Seriously Fish recommends a base footprint of at least 45 × 30 cm and about 41 litres for a group. This describes usable space, not a guarantee that every tank of that volume is suitable. Use dense planting along parts of the perimeter, floating plants and roots for cover, while leaving open swimming room. Avoid strong currents. Add the fish only to a biologically mature aquarium where water conditions do not fluctuate sharply.Water conditions
The specialist care profile gives 20–28°C, pH 4.0–6.5 and GH 1–5 dGH. These are reported care limits for a fish from soft, acidic blackwater; they are not a reason to chemically push a healthy aquarium rapidly toward an extreme. Stability matters. Test source and aquarium water, avoid sudden changes and keep ammonia and nitrite at zero. Acclimate gradually with attention to the fish’s origin and transport conditions.Behaviour and group size
Boraras merah is peaceful but small and reserved. The species-specific source recommends at least 8–10 fish; an appropriate group encourages natural shoaling and may reduce nervousness. A species-only aquarium is a dependable choice. Only very small, calm species with compatible water requirements should be considered as companions. Large, fast or territorial fish may outcompete or prey on the rasboras. Check after feeding that every fish is eating.Feeding
The species is considered a micropredator of tiny insects, worms, crustaceans and other zooplankton. Offer small live or frozen foods, such as finely presented Daphnia or Artemia, alongside quality dried food of a suitable particle size. Crumble flakes if needed and divide meals into small portions. Coarse food can lead to competition and poor intake. Remove leftovers; overfeeding can quickly affect water quality in a small-fish aquarium.Breeding
The fish scatters eggs among plants and provides no parental care. Fry may occasionally survive in a mature, densely planted aquarium, but adults can eat eggs and larvae. For deliberate breeding, a separate quiet, dim setup with fine-leaved material and egg protection is more suitable. Newly hatched fry are exceptionally small and initially need microscopic food. Results depend on condition and setup; a fixed yield or hatch time cannot be guaranteed.Suitable products
Recommended staple foods
Tropical Supervit Basic 100ml
Complete flake food for animal-eating fish. Crumble it very finely for this tiny mouth and check that shy individuals feed.
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Tropical Dafnia 100ml
Dried Daphnia as an occasional supplement. Break it into tiny pieces and continue to provide a complete staple food.
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Sources & review
This care guide draws on several specialist sources and was last checked on .