Emerald Dwarf Rasbora (Microdevario erythromicron) Care Guide
A stunningly colored micro fish endemic to Inle Lake in Myanmar. Features alternating vertical bands of emerald green and orange-pink, with bright orange fins.
Compiled by Aquairi from published sources · Published · Updated
Overview
Microdevario erythromicron is a species in the family Cyprinidae. A stunningly colored micro fish endemic to Inle Lake in Myanmar. Features alternating vertical bands of emerald green and orange-pink, with bright orange fins. Males display more intense coloration and engage in fascinating sparring displays. Prefers cooler water than most tropical fish, reflecting its high-altitude lake origins.
Taxonomy
- Family: Cyprinidae
- Genus: Microdevario
- Scientific name: Microdevario erythromicron
- Other names: Microrasbora erythromicron, Myanmar Dwarf Rasbora
- Origin: Southeast Asia
Habitat
Endemic to Inle Lake and adjacent waters of the Shan Plateau in Myanmar. Inhabits shallow, clear, slightly alkaline water among dense marginal vegetation. A small shoaling cyprinid with emerald-green vertical bars, formerly placed in the genus Microrasbora.
Tank requirements
- Minimum tank volume: 40 L
- Temperature: 20-25 °C
- pH: 7-8
- GH: 5-15 °dGH
- Water flow: low
- Adult size: 2-3 cm
- Lifespan: 3-5 years
- Recommended group size: ≥ 10
- Difficulty: intermediate
Diet
Classified as omnivore. Recommended feeding frequency: 2x daily. In captivity, offer a varied diet appropriate to the species — quality prepared foods supplemented with frozen or live items of suitable size.
Compatibility
- Temperament: peaceful
- Swimming level: middle
- Compatible tank mates: Celestial Pearl Danio, Pygmy Corydoras, Cherry Shrimp, Otocinclus, Other Inle Lake species
- Avoid with: Large or aggressive fish, Very warm water species
Breeding
- Breeding strategy: egg-scatterer
- Breeding difficulty: intermediate
Emerald Dwarf Rasbora Breeding Guide
Overview
Microdevario erythromicron (also placed in Celestichthys and historically Microrasbora) is an egg-scattering cyprinid endemic to Inle Lake in Myanmar, where it is listed as Endangered on the IUCN Red List. It is an egg-scattering spawner that shows no parental care, and conditioned adults spawn readily, making it an attainable subject for an intermediate aquarist who can dedicate a small breeding container.
Sexing
Females grow slightly larger and develop a noticeably rounder belly, especially when gravid. Males show well-defined iridescent blue vertical bars on the flanks and more red colouration in the fins. These differences become clearest on well-fed, mature fish.
Conditioning
Condition adult groups together on a varied diet so that males colour up and females fill with eggs. The species prefers cooler, harder water than most tropical fish, reflecting its high-altitude lake origin. Maintenance parameters are a temperature of 20-24 degrees Celsius, pH 7.0-8.0 and hardness of roughly 215-357 ppm; it does not thrive in acidic water.
Breeding Setup
Transfer selected pairs or small groups to a separate 10-15 litre container filled with aged water. Densely plant it with fine wool mops or Taxiphyllum so that scattered eggs fall out of reach. Neither lighting nor filtration is strictly necessary, though a small air-powered sponge filter may be used.
Spawning Behavior & Trigger
Adults in good condition spawn regularly, depositing around 30 mildly adhesive eggs in a typical event among the plants or mops. Because the parents will eat any eggs they find, they must be removed immediately after spawning.
Egg & Fry Care
Incubation takes around 72 hours, and the fry become free-swimming about 3-4 days later. Begin feeding with Paramecium or a proprietary dry food of 5-50 micron grade, then introduce Artemia nauplii and microworms once the fry are large enough to accept them.
Common Challenges
The main losses come from egg predation, so prompt removal of adults is essential. The small clutch size means yields per spawn are modest, and the fry's tiny initial gape demands genuinely small first foods such as infusoria-grade cultures before Artemia. Because the species naturally favours cooler, harder, near-neutral to alkaline water, attempts to spawn it in the warm, soft, acidic conditions used for many tropical egg-scatterers tend to fail; matching the Inle Lake profile of 20-24 degrees Celsius and pH 7.0-8.0 is more important than any single trigger. Its Endangered IUCN status also makes captive propagation worthwhile, so prioritising stable, well-conditioned breeding stock benefits the species as well as the aquarist.