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Celestichthys erythromicron, commonly known as the Emerald Dwarf Rasbora or Emerald Dwarf Danio, is a minute, vibrantly colored freshwater fish belonging to the family Cyprinidae. It is highly prized in the aquarium hobby for its striking coloration, small size, and peaceful demeanor. This species exhibits a distinctive pattern of iridescent emerald-green vertical bars on a reddish-orange to pinkish body, making it easily distinguishable. It is a shoaling species that thrives in well-planted aquariums, mimicking its natural habitat of dense vegetation.
Physical Characteristics
- Body shape
- elongated
- Coloration
- The body is primarily reddish-orange to pinkish, adorned with 10-14 iridescent emerald-green to bluish-green vertical bars that extend from the dorsal surface to the ventral side. The fins are largely translucent, sometimes with a faint reddish tint, especially in males. Males typically exhibit more intense coloration and may have redder fins, particularly the anal and caudal fins, and a more pronounced emerald barring.
- Scale type
- cycloid
- Mouth position
- superior
- Distinctive features
- Small size, typically not exceeding 2.5 cm (1 inch) in total length., Distinctive pattern of iridescent emerald-green vertical bars., Sexual dimorphism: males are generally more brightly colored and slender, while females are rounder, especially when gravid.
- Dorsal fin
- Single, relatively small, positioned mid-body.
- Tail fin
- Forked, with rounded lobes.
- Pectoral fin
- Small and transparent, positioned ventrally behind the operculum.
- Distinctive fins
- All fins are generally clear to slightly reddish, lacking prominent markings.
Identification Tips
Size
Adults rarely exceed 2.5 cm (1 inch) in total length, making them one of the smallest cyprinids.
Coloration and Pattern
Look for the characteristic reddish-orange body with 10-14 distinct, iridescent emerald-green vertical bars. This pattern is unique among similar small cyprinids.
Mouth Position
The mouth is upturned (superior), indicating a surface or mid-water feeder.
Fin Coloration
Males often display more intense red coloration in their fins, particularly the anal and caudal fins, compared to the more subdued females.
Habitat
- Water type
- freshwater
- Depth
- Shallow, typically found in the upper water column among vegetation.
- Environment
- Found in small, shallow, heavily vegetated ponds and swamps, often with clear water and a substrate of mud or detritus. These habitats are typically slow-moving or stagnant, with dense aquatic plant growth providing cover and foraging grounds.
- Geographic range
- Endemic to Lake Inle and its surrounding basin in Shan State, Myanmar (Burma). Its distribution is highly restricted to this specific region.
Aquarium Information
- Care level: intermediate
- Temperament: peaceful
- Diet: omnivore
- Minimum tank size: 10 gallons (38 liters)
- Temperature: 20-26°C (68-79°F)
- pH level: 6.5-7.5
- Hardness: 5-15 dGH
- Compatibility: Excellent for community tanks with other small, peaceful fish such as other dwarf rasboras, microdevario species, small tetras, corydoras, and peaceful shrimp. Avoid housing with larger or aggressive fish that may prey on them or outcompete them for food.
- Special requirements: Requires a well-planted aquarium with plenty of hiding spots and open swimming areas. A dark substrate can enhance their coloration. They are sensitive to poor water quality, so stable parameters and regular water changes are crucial. Best kept in groups of 8 or more to encourage natural schooling behavior and reduce shyness.
Wild Information
- Conservation status: least concern
- Seasonality: No specific seasonal behavior patterns are documented for wild populations beyond general reproductive cycles influenced by environmental conditions.
- Market price: Typically $3-$7 USD per fish, varying by region and supplier.
- Commercial importance: medium
- Taste: Not applicable due to its minute size; not consumed.
- Texture: Not applicable due to its minute size; not consumed.
- Nutritional value: Not applicable due to its minute size; not consumed.
Key Facts
Taxonomic Reclassificationevolution
Originally described as Microrasbora erythromicron, this species was reclassified into the genus Celestichthys in 2007, along with the Celestial Pearl Danio (Celestichthys margaritatus), due to genetic and morphological distinctiveness from other Microrasbora species.
Endemic to Lake Inleinteresting
The Emerald Dwarf Rasbora is found exclusively in the Lake Inle basin in Myanmar, making it an endemic species with a very restricted natural range.
Micro-predatorbehavior
Despite its small size, C. erythromicron is a micro-predator, feeding primarily on small invertebrates such as copepods, cladocerans, and insect larvae in its natural habitat.
Shoaling Behaviorbehavior
These fish are highly social and exhibit strong shoaling behavior. Keeping them in groups of 8 or more not only reduces stress but also encourages more natural and interesting interactions.
Safety Information
Safe- Safety level: safe
- Venomous: No
- Edibility: not recommended
- Handling notes: No specific handling precautions are required beyond general care for small, delicate fish. Avoid sudden movements or loud noises near the aquarium as they can be easily startled. Do not handle with bare hands if possible, use a fine-mesh net to minimize stress and injury.
Similar Species
Celestial Pearl Danio
Celestichthys margaritatus
The Celestial Pearl Danio (CPD) has a dark blue to black body with numerous iridescent pearl-like spots, and red-orange fins with black markings. In contrast, C. erythromicron has a reddish-orange body with emerald-green vertical bars and generally clear fins.
Danio erythromicron
Danio erythromicron
This is a former scientific name (synonym) for Celestichthys erythromicron. The species was reclassified into the genus Celestichthys. Morphologically, they are the same fish, but the current accepted scientific name is Celestichthys erythromicron.
Microrasbora rubescens
Microrasbora rubescens
Microrasbora rubescens is a larger species (up to 3.5 cm) with a more uniform reddish body coloration and lacks the distinct emerald-green vertical bars of C. erythromicron. It also has a more elongated, torpedo-shaped body.
Scientific Classification
- Kingdom
- Animalia
- Phylum
- Chordata
- Class
- Actinopterygii
- Order
- Cypriniformes
- Family
- Cyprinidae
- Genus
- Celestichthys
- Species
- erythromicron
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