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FishintermediateFreshwater

Neon Rasbora

Sundadanio axelrodi

AnimaliaChordataActinopterygiiCyprinidae

📍 Mekong Basin, Southeast Asia

Ask Finn

Sundadanio axelrodi, the Neon Rasbora (also called Axelrod's Rasbora), is a stunning nano fish from Borneo and Sumatra whose body radiates intense neon-blue to blue-green iridescence along its flanks. At just 2 cm (0.8 in) it ranks among the smallest cyprinids, requiring soft blackwater conditions similar to its peat swamp habitat. Its striking colour and active schooling behaviour make it a prized centrepiece in nano planted aquariums.

Size1.5"
Min Tank10g
School6+
peaceful
Zonemid

Care Guide

Diet

Neon Rasboras are carnivorous and require small live or frozen foods such as micro worms, baby brine shrimp, and daphnia. High-quality micro pellets designed for nano fish can supplement live foods. Feed small amounts once daily, offering only what they can consume in a few minutes to maintain water quality in small tanks.

Behavior

These fish are highly active schoolers that display their brilliant neon-blue coloration most vividly when kept in groups of 10 or more. They are peaceful and spend most of their time in mid-water zones, darting and weaving through plants in constant motion. They are best suited to species-specific or carefully curated nano community tanks and may become stressed or lose color in larger, more aggressive setups.

Breeding

Breeding Neon Rasboras in captivity is difficult and rarely achieved in home aquariums. They require very soft, acidic blackwater conditions with dense vegetation and stable temperatures around 24–25 °C. Fry are extremely small and require infusoria or liquid fry food; success requires dedicated breeding tanks and expert-level care.

Common Diseases

Ich (Ichthyophthirius multifiliis)

Symptoms

White spots on body and fins, rapid breathing, lethargy, rubbing against objects

Treatment

Raise temperature gradually to 28–29 °C over 24 hours and maintain for 7–10 days; use aquarium salt at half-dose for sensitive nano fish; perform daily 25% water changes

Fin Rot

Symptoms

Frayed or deteriorating fin edges, discoloration, lethargy

Treatment

Perform 50% water change immediately, improve water quality, reduce stocking density, and treat with antibacterial medication if severe; ensure pristine water parameters

Bacterial Infection

Symptoms

Cloudy eyes, open sores, loss of color, clamped fins, rapid breathing

Treatment

Perform daily 30% water changes, maintain optimal water parameters (pH 4.0–6.5, ammonia 0 ppm), and consider broad-spectrum antibacterial treatment in severe cases

Stress-Related Color Loss

Symptoms

Fading of neon-blue coloration, hiding behavior, reduced activity

Treatment

Ensure group size of at least 10 fish, provide dense vegetation for security, maintain stable soft acidic water, and minimize tank disturbances

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Quick Facts

diet
Carnivore – micro worms, baby brine shrimp, micro pellets
lifespan
3–5 years
max size
2 cm (0.8 in)
tank size
5 gallons minimum
school size
10+
temperament
Peaceful, schooling; species tank or nano community only

Water it likes

ph
4.0–6.5
ammonia
0 ppm
nitrate
<10 ppm
hardness
0–4 dGH
temperature
72–79°F (22–26°C)

Stats

Community tips0
Kept by0 hobbyists