Crossbanded dwarf rasbora - Danio erythromicron

Scientific name: Danio erythromicron

Common name: Crossbanded dwarf rasbora

Family: Cyprinidae

Usual size in fish tanks: 2 - 3 cm (0.79 - 1.18 inch)

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Recommended pH range: 6.5 - 7.6

Recommended water hardness: 3 - 13°N (53.57 - 232.14ppm)

0°C 32°F30°C 86°F

Recommended temperature range: 21 - 26 °C (69.8 - 78.8°F)

The way how these fish reproduce: Spawning

Where the species comes from: Southeast Asia

Temperament to its own species: peaceful

Temperament toward other fish species: peaceful

Usual place in the tank: Middle levels

General Information

The Emerald / Crossbanded Dwarf Rasbora (Danio erythromicron) is a tiny, peaceful shoaling cyprinid endemic to the Lake Inle basin (Shan State, Myanmar). In nature it inhabits shallow, vegetated margins and channels among floating vegetation, which translates in aquaria to dense planting, gentle flow and subdued light. Adults reach about 2–3 cm. Note the modern placement in Danio; older sources and some hobby sites still list Microrasbora (and occasionally Celestichthys).

Food & Feeding

An omnivorous micro-predator. Use quality micro-flakes or tiny granules as the staple, then rotate small live and frozen foods: Artemia nauplii, daphnia, cyclops, microworms, finely chopped bloodworms. Feed very small portions 1–2× daily so everything is eaten within minutes (they have tiny mouths).

Sexing

Males are typically slimmer and more intensely colored with brighter orange-red finnage; females are fuller-bodied, especially when gravid. Sexing juveniles is unreliable.

Breeding

Egg-scattering spawner with no parental care. Condition adults well, then use a separate, dimly lit tank with fine-leaved plants or spawning mops. Spawning often occurs at dawn; remove adults post-spawn to prevent egg predation. Eggs hatch in ~24–72 h depending on temperature, and fry are free-swimming a few days later—start with infusoria/micro foods before introducing newly hatched brine shrimp. Many aquarists report frequent, low-key spawning in well-kept planted tanks.

Lifespan

Typically 3–5 years with clean, cool-to-mild temperatures, good oxygenation, and a varied diet—consistent with other miniature danionins.

Tank Requirements & Water Parameters

Footprint: length and plant density matter more than height; even nano groups benefit from 45–60 cm (18–24″) for stability.
Water: soft to moderately hard, slightly acidic to neutral.
Temperature: a cool-subtropical species from a high-plateau lake; aim for 21–26 °C (70–79 °F), with many keepers favoring the lower/middle end for color and longevity.
Layout: dark substrate, dense planting with floating plants to diffuse light; gentle filtration/flow; high oxygenation.
Maintenance: small, regular water changes; avoid abrupt parameter swings.

Compatibility & Tank Mates

Very peaceful and shy. Keep in a proper shoal (ideally 8–12 ) for confidence and natural displays. Combine with equally small, calm species (e.g., tiny rasboras/tetras), peaceful shrimp/snails, and avoid boisterous or large fish that outcompete them at feeding.

Behaviour & Usual Place in the Tank

Middle to upper levels: a mid-water shoaler that often cruises just below the surface among plants, dropping lower when startled. Provide open lanes between thickets for group displays.

Short Description

Danio erythromicron is a tiny, Lake Inle endemic well-suited to calm, planted aquaria. Keep cool-mild temperatures, soft-neutral, clean water, dense cover and a varied micro-food diet; expect peaceful schooling behavior and occasional spontaneous spawning.

Q&A

South Asia or Southeast Asia? Southeast Asia—specifically Myanmar (Lake Inle basin).
Current name? Valid as Danio erythromicron; older literature uses Microrasbora and some hobby sources list Celestichthys.
How big & how long? About 2–3 cm; lifespan commonly 3–5 years with good care.
Breeds in community tanks? Sometimes—adults may scatter eggs among plants, but fry survival is higher in a dedicated setup.