Emerald Dwarf Rasbora
Danio erythromicron
Danionidae
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About
The emerald dwarf rasbora is not a rasbora. It is a danio: described from Lake Inle in Myanmar in 1918 as Microrasbora erythromicron, moved into Danio once DNA placed its closest relatives as Danio margaritatus (the celestial pearl danio) and Danio choprae, and filed by Seriously Fish today under a third name again, Celestichthys erythromicron. The trade never updated the label, so a 2.5 cm fish carrying up to fifteen iridescent emerald bars and a copper-rimmed spot at the tail base still reaches shops under a genus it left decades ago. What the name costs you is practical, not academic: buyers reach for soft, acidic blackwater because that is what rasboras want, and this fish comes from a cool, hard, alkaline highland lake at 880 m. It behaves like a danio too — rival males spar over sightlines all day long, which is charming in a big group and lethal in a group of four. Lake Inle is under heavy pressure and the IUCN lists the species as Endangered, so nearly all stock in the trade is now captive-bred.
Care
Buy a real group. Ten is a working minimum and Seriously Fish argues for twenty or more, because a crowd is what stops sparring males fixating on one victim. Give it a mature, densely planted tank from 45 litres over a 60 cm base, cool water at 21-23 °C, and hard, alkaline chemistry (pH 7-8, GH 10-20) — the opposite of standard nano-fish advice. It is shy and slow to the food, so boisterous or fast tankmates will keep it hiding and hungry; other small Myanmar cyprinids suit it best. Do not house it with the celestial pearl danio: Seriously Fish calls the two probably capable of hybridisation and notes limited evidence that they already have been crossed.
Diet
Micropredator with a tiny mouth. Crushed dry food as a base, plus live or frozen Daphnia, cyclops and Artemia nauplii several times a week for colour and condition.
Tankmate compatibility
Gets along with (115)
Possible with care (222)
Avoid (81)
Computed by the AquaSage engine for a spacious reference tank — always check the full verdict for your exact setup in the calculator.
Telling males from females
What works for this species, most reliable first.
- Belly depthA hint only · only on well-fed adults, and only as a comparison
For most tetras, barbs and rasboras this is all there is: a conditioned female is deeper through the belly than a male of the same length.
Also in these lists
Similar species
Same category and the closest water parameters — if this species isn't quite it, start here.
Sold in Lithuania
These Lithuanian shops listed this species in their public catalogue (checked August 8, 2026). Stock moves — ask before you travel.
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Frequently asked questions
- What tank size does a Emerald Dwarf Rasbora need?
- A Emerald Dwarf Rasbora needs an aquarium of at least 45 litres (11.9 US gallons) with a footprint at least 60 cm (23.6 in) long — for this species, swimming length matters as much as raw volume.
- What water parameters does a Emerald Dwarf Rasbora need?
- Emerald Dwarf Rasbora does best at 20–25 °C (68–77 °F), pH 7–8.2 and a general hardness of 10–20 °dGH.
- What group size does a Emerald Dwarf Rasbora need?
- Emerald Dwarf Rasbora is a social species — keep a group of at least 10 so natural behaviour emerges and stress stays low.
- Is the Emerald Dwarf Rasbora suitable for beginners?
- Emerald Dwarf Rasbora sits in the middle of the difficulty scale — manageable for a careful beginner who has done the reading, but it has specific needs worth researching first.