How to Breed Phoenix Rasboras: Micro Eggs in Soft Water
The phoenix rasbora (Boraras merah) is one of the smallest and most jewel-like fish available to nano tank enthusiasts — adults barely reach 2 cm. Breeding them is a quiet challenge that rewards patience and attention to water chemistry over brute-force techniques. This breed phoenix rasbora guide from Gensou Aquascaping at 5 Everton Park, Singapore, takes you through conditioning, spawning, and raising near-invisible fry in soft, acidic water. If you have ever wanted to propagate something truly miniature, this is your project.
Understanding the Species
Boraras merah originates from the blackwater peat swamps of Borneo and Sumatra, where pH can drop below 4.0 and water is stained deep amber with tannins. In captivity, they thrive at pH 5.0-6.5 with negligible hardness. Singapore’s PUB tap water sits around GH 2-4 and is naturally soft, which gives local breeders a genuine head start — you are already halfway to ideal conditions before any adjustments. These fish are egg scatterers, not mouthbrooders, and offer no parental care whatsoever.
Conditioning Breeders
Select your healthiest, most intensely coloured adults — males display a deeper red with a distinct dark lateral blotch. Separate males and females for 7-10 days if possible, feeding heavily with live foods. Vinegar eels, micro worms, and freshly hatched baby brine shrimp are ideal conditioning foods. Two to three small feeds daily will bring females into breeding condition; a plump belly when viewed from above indicates she is carrying eggs. Six to eight adults in a conditioning group is sufficient.
Setting Up the Breeding Tank
A 10-20 litre container is all you need. Fill it with aged, soft water — TDS below 50 ppm, pH 5.5-6.0, temperature 26-27 °C. Add a clump of Java moss or a spawning mop that reaches the bottom, as phoenix rasboras scatter eggs into fine-leaved vegetation. Dim lighting encourages spawning; a sheet of cardboard around three sides of the tank reduces disturbance. No filtration is ideal during spawning, though a mature sponge filter on the lowest flow setting is acceptable. Tannin-stained water from catappa leaves or peat extract mimics their natural habitat and has mild antifungal properties that protect eggs.
The Spawning Process
Introduce two or three pairs into the breeding tank in the evening. Spawning typically occurs at first light the following morning. Males chase females through the moss, and eggs are released in tiny batches of two to five at a time over several hours. Total egg counts per female are modest — usually 10-30 per spawning event. The eggs are nearly transparent and barely 0.8 mm in diameter, making them extremely difficult to spot. Remove the adults within 24 hours of spawning, as they will eat every egg they find.
Egg and Fry Care
Eggs hatch in approximately 24-36 hours at 27 °C. The fry are essentially invisible to the naked eye for the first three days while they absorb their yolk sacs. Once free-swimming, they need infusoria or paramecium cultures as a first food — anything larger is simply too big for their mouths. After 7-10 days, you can transition to vinegar eels and then to freshly hatched baby brine shrimp nauplii by week three. Maintain pristine water quality with tiny daily water changes of 10% using matched parameters. Even small ammonia readings are lethal at this scale.
Growth and Juvenile Rearing
Phoenix rasbora fry grow slowly. Expect them to reach 5 mm by the one-month mark and roughly 1 cm by three months. Keep the rearing tank dimly lit with floating plants like Salvinia to provide microorganism grazing surfaces and reduce stress. A gentle sponge filter keeps water moving without creating dangerous suction. Juvenile colouration begins to develop around 6-8 weeks, with the characteristic red hue intensifying over the following months.
Common Breeding Challenges
Fungus on eggs is the most frequent issue and usually results from water that is too hard or too clean — the lack of tannins removes natural antifungal protection. If you see white fuzzy eggs within 12 hours, check your TDS and add more catappa extract. Low fry survival often comes down to first-food availability; start your infusoria culture at least a week before you expect spawning so it is ready when the fry become free-swimming. Patience is essential — do not expect large batches from these micro fish.
Rewarding Micro Breeding
Successfully raising Boraras merah fry from near-invisible eggs to glowing red juveniles is deeply satisfying. Singapore’s naturally soft water makes the chemistry straightforward, and the small tank footprint fits easily into any HDB setup. This breed phoenix rasbora guide gives you a repeatable method — condition well, spawn in soft tannin-rich water, feed microscopic first foods, and be patient. The results are tiny, beautiful, and entirely worth the effort.
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Still Have Questions About Your Tank?
Drop by Gensou Aquascaping — most walk-in questions get answered in under 10 minutes by someone who has set up hundreds of tanks.
5 Everton Park #01-34B, Singapore 080005 · Open daily 11am – 8pm
