Emerald dwarf rasbora
Danio erythromicron
A micro-fish endemic to Lake Inlé in Myanmar, with vertical emerald green and orange bands on a translucent body — a tiny jewel reaching just 2 cm. Despite its common name containing 'rasbora', it is scientifically a Danio. Requires alkaline, hard water (pH 7.0–8.0), an exception compared to many tropical nano fish. In groups of 8–10+ in densely planted tanks with dim lighting, males display competitive behaviors that enhance coloration. Males may spar in groups that are too small.
Température de l’eau
20 - 24 °C
Valeur du pH
7 - 8
Type d'eau
Eau douce
Niveau dans le bac
Milieu
Taille adulte
2,5 cm
Volume minimal du bac
>= 40 L
Groupe minimal
>= 8
GH
10 - 20 dGH
KH
2 - 10 dKH
TDS
170 - 400 ppm
Conductivité
266 - 625 uS/cm
Description de l'espèce
Geographical Origin and Habitat: Endemic to Lake Inle in Myanmar. Lives in calm and crystalline waters surrounded by limestone mountains, hiding among the dense expanses of floating islands of vegetation.
Taxonomy and Morphology: Emerald Dwarf Rasbora (Danio erythromicron, formerly Microrasbora). Miniature cyprinid, totally lacks barbels (a rare feature for Danios) and has a compact and stocky body shape.
Social Behavior: Extremely shy and reserved. Must be kept in colonies of 15-20 specimens; in smaller numbers it will hide perpetually. Males engage in ritual dances with flared fins, creating temporary micro-territories.
Coloration and Sexual Dimorphism: Stunning: emerald green or iridescent coppery body, banded by 12-15 thin vertical dark blue/black stripes. Black spot at the base of the tail, orange fins. Females are more faded, silvery and with a round belly.
Soins, reproduction et cohabitation
Aquarium Setup: Nano-aquariums (minimum 60 cm / 24 inches) densely, if not obsessively, planted. Use dark bottoms, floaters and mosses (Taxiphyllum) to shield the light and instill security. Practically still water (no strong currents).
Diet and Feeding: Micro-predator. Hardly comes to the surface. Must be fed in the water column with very small live or frozen food (brine shrimp nauplii, microworms, cyclops, daphnia). Crumbled dry food is accepted with difficulty.
Water Quality: Limestone upland fish. Tolerates pH up to 8.0 and very hard waters well. On the other hand, it suffers from excessively acidic and soft water, or tropical tanks kept stably over 26°C (79°F).
Compatibility and Cohabitation: Not suitable for typical community aquariums, it would be bullied or its food ignored. Pair it only with other nano species (Boraras, Danio margaritatus) and small Caridina or Neocaridina shrimp.
Aquarium Breeding: They lay a very few slightly adhesive eggs daily among the moss. By regularly removing the moss to place it in separate small tanks, fry will be obtained, to be fed with infusoria.
Risks and Diseases: Rapid wasting if placed in bare or brightly lit tanks. Easy prey to skin parasites if stressed by the presence of large fish.
Origine et répartition géographiques
Endemic to Lake Inle in Myanmar. Lives in calm and crystalline waters surrounded by limestone mountains, hiding among the dense expanses of floating islands of vegetation.
Origine
Asie du Sud et du Sud-Est
Profil de poisson
- Tempérament
- Peaceful
- The Emerald Dwarf Rasbora is completely peaceful toward other species but can be highly timid and easily stressed. Within their own species, males are quite combative, constantly engaging in harmless, flared-fin sparring matches to establish dominance. Providing a large enough group and dense planting is key to making them feel bold enough to display.
- Régime alimentaire
- Omnivore
- In their natural habitat, they feed on micro-invertebrates and zooplankton. In captivity, they require very small foods such as crushed high-quality flakes, micro-pellets, and finely powdered fry food. Live foods like microworms, newly hatched brine shrimp, and daphnia are highly recommended to encourage them to forage.
- Espérance de vie
- 3-5 years
- Taille adulte
- 2.5 cm
- Ratio des sexes
- Group
- Males are noticeably more colorful, displaying bright emerald bars and reddish-orange fins, while females are duller and plumper. Males will constantly spar and display to one another, so keeping a higher ratio of females to males helps distribute this aggression. A group of at least 8-10 individuals is highly recommended.
- Fréquence d'alimentation
- Twice daily
- Due to their small stomachs and fast metabolism, they should be fed tiny amounts of food twice a day. They are timid feeders that will carefully inspect food before consuming it, often preferring items slowly sinking through the water column. Ensure that food reaches their hiding spots if they are reluctant to come out.
- Charge biologique
- Low
- The Emerald Dwarf Rasbora is a very small fish that produces a minimal bioload, making it ideal for nano aquariums. Even a sizable group will have a negligible impact on a well-cycled tank's filtration system. However, their sensitivity to poor water quality means regular small water changes are still mandatory.
- Courant
- Strong
- They originate from Lake Inle in Myanmar, which has relatively still, calm waters densely packed with vegetation. They prefer low to moderate flow in the aquarium, as strong currents will quickly exhaust these small fish. Gentle filtration from a sponge filter or a baffled hang-on-back filter is ideal.
- Risque de saut
- No
- Reproduction
- Oviparous
- They are egg scatterers that are relatively easy to breed in a dedicated, densely planted breeding tank. Females will deposit a few adhesive eggs daily among fine-leaved plants like Java moss. The parents will eat the eggs and fry, so adult fish should be removed after a few days of spawning.
- Compatibilité et compagnons
- Peaceful
- They are incredibly peaceful but exceptionally shy, making them suitable only for species-only setups or tanks with other timid nano fish. Larger or overly active tank mates will outcompete them for food and force them into constant hiding. Excellent companions include Boraras species, pygmy corydoras, and Neocaridina shrimp.
- Niveau dans le bac
- Middle
- They are reclusive fish that primarily occupy the middle and lower levels of the aquarium, rarely venturing to the very top. They strongly prefer densely planted tanks where they can weave in and out of the vegetation. Without abundant hiding places, they will remain stressed and pale.
Modèles et paramètres scientifiques
FishBase
Fenêtre sur les données scientifiques officielles de l’espèce
FishBase v25.04Données synchronisées le : 15/06/2026
- Niveau trophique
- 3 ± 0,4 se
- Résilience
- Élevée (moins de 15 mois)
- Singularité phylogénétique (PD50)
- 0.5
- Relation bayésienne longueur-poids
- a = 0.00977, b = 3.04
- VulnérabilitéVulnérabilité faible (10 / 100)
Galerie d'images
Images sous licence liées à l'espèce ou, lorsqu'elles sont indiquées, au taxon représentatif le plus proche.
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