Blue Neon Rasbora (Sundadanio axelrodi)

A rare, ultra-small blue nano fish for mature blackwater, soft-water, and heavily planted aquariums.

Blue Neon Rasbora is one of the most beautiful nano schooling fish in the freshwater aquarium hobby. Also searched as Neon Blue Rasbora, Blue Axelrodi Rasbora, Axelrod’s Rasbora, or Sundadanio axelrodi, this tiny fish is known for its glowing blue to blue-green body sheen, delicate movement, and peaceful behavior.

This is not a normal beginner rasbora. Blue Neon Rasboras are extremely small and sensitive, so they are best kept in mature aquariums with soft, stable water, gentle filtration, heavy planting, and very peaceful tank mates. In the right setup, they create a refined, high-end nano display that looks very different from common community fish.

Because they are so small, the best display comes from a proper group. A single fish or tiny group will not show the same confidence, natural movement, or visual impact as a larger school.

Why this fish stands out

• Rare nano schooling fish with glowing blue to blue-green coloration
• Also known as Blue Axelrodi Rasbora or Neon Blue Rasbora
• Excellent choice for blackwater, soft-water, and planted nano aquariums
• Peaceful and suitable for very calm micro community tanks
• Beautiful contrast against dark substrate, botanicals, and dense plants
• Much more refined and unusual than common beginner rasboras

Best for

• Experienced nano fish keepers
• Blackwater aquariums
• Soft-water planted tanks
• Peaceful micro community aquariums
• Customers looking for rare nano fish in Canada
• Aquarists who enjoy delicate, subtle, high-end schooling fish

Topick Aquarium Insight

Blue Neon Rasbora is the kind of fish that rewards stability, patience, and proper setup. Many nano fish are marketed as easy because they are small, but small size does not always mean easy care. With this species, water stability, gentle tank mates, and low stress are much more important than simply choosing a small aquarium.

This fish should not be treated like a hardy community rasbora. It is better suited for aquarists who can provide a mature, quiet aquarium with soft water, established plants, and careful acclimation.

The best way to enjoy them is not to buy one or two as decoration. Keep them in a proper group, give them dark contrast, and allow them time to settle. Once comfortable, their blue glow becomes much more visible and the whole group looks far more natural.

Blue Neon Rasbora vs Other Nano Fish

Blue Neon Rasbora is much more delicate than many common nano fish such as Ember Tetras, Chili Rasboras, Celestial Pearl Danios, or White Cloud Mountain Minnows. It is best chosen for a stable soft-water setup rather than a new beginner aquarium.

• Blue Neon Rasbora: rare, delicate, soft-water nano fish with glowing blue colour
• Chili Rasbora: red, tiny, still soft-water friendly but more commonly available
• Celestial Pearl Danio: more structured body pattern, cooler-water tolerant, less blackwater-focused
• Neon Green Rasbora: brighter green display fish, usually more adaptable than Blue Neon Rasbora

Choose Blue Neon Rasbora if you want a rare, subtle, premium nano fish for a carefully prepared aquarium.

Behavior & Group Size

Blue Neon Rasboras are peaceful schooling fish. They feel safest in groups and should be kept with other very calm, small fish.

We recommend keeping at least 8–10 fish, with 10 or more being much better for confidence, movement, and visual impact. Larger groups also reduce stress and make the fish more visible in planted tanks.

Tank Setup

A mature, stable aquarium is strongly recommended. This fish is not ideal for brand-new tanks, unstable tap-water setups, or aggressive community aquariums.

• Minimum recommended tank: 10 gallons for a small group
• 15–20 gallons or larger preferred for a better school
• Heavily planted aquarium strongly recommended
• Soft, acidic, stable water preferred
• Gentle filtration and low to moderate flow
• Dark substrate and botanicals help bring out colour
• Floating plants or shaded areas reduce stress

A blackwater-style aquascape with leaf litter, driftwood, botanicals, and dense plants is ideal. Bright, open, high-flow tanks may make them feel exposed and less colourful.

Water Parameters

• Scientific Name: Sundadanio axelrodi
• Common Names: Blue Neon Rasbora, Neon Blue Rasbora, Blue Axelrodi Rasbora, Axelrod’s Rasbora
• Temperature: 22–27°C
• pH: 5.0–7.0 preferred
• Hardness: Soft water strongly preferred
• Adult Size: approximately 2 cm
• Temperament: Very peaceful
• Diet: Micro predator / small omnivore
• Care Level: Intermediate to Advanced

Stable soft water is the key. Avoid hard, unstable, or freshly set up aquariums. RO-based water or soft conditioned water may be helpful depending on your local tap water.

Feeding

Blue Neon Rasboras are tiny fish with very small mouths. Food size matters more than many customers expect.

• Baby brine shrimp
• Frozen cyclops
• Frozen daphnia
• Very fine micro pellets
• Crushed high-quality flakes
• Powdered nano fish food
• Infusoria-style micro foods for very small individuals

Feed small amounts carefully. They can be outcompeted by faster or larger fish, so make sure food reaches them directly. Multiple small feedings are often better than one large feeding.

Tank Mates

Choose only very peaceful tank mates. Blue Neon Rasboras are too small and delicate for active, aggressive, or large community fish.

• Chili Rasboras
• Exclamation Point Rasboras
• Small Boraras species
• Peaceful dwarf shrimp in suitable setups
• Small peaceful Corydoras such as pygmy or habrosus in larger suitable tanks
• Very calm micro community fish

Avoid angelfish, bettas with strong hunting behavior, barbs, larger tetras, gouramis, rainbowfish, and any fish large or active enough to intimidate or eat them.

Shrimp Tank Compatibility

Blue Neon Rasboras can work in peaceful shrimp tanks, especially mature planted aquariums with moss and cover. They are not active shrimp predators, but like almost all small fish, they may eat very tiny shrimplets if given the chance.

Adult shrimp are usually safe in a proper setup. For maximum shrimp breeding, a shrimp-only tank is still best.

Colour & Sex Differences

Blue Neon Rasbora colour can vary depending on sex, locality, age, lighting, stress level, and water conditions. Males are usually more colourful, while females may appear fuller-bodied and more subtle.

• Males: stronger blue or blue-green glow, often darker fin contrast
• Females: fuller body, usually more subtle colour
• New arrivals: may look pale until settled
• Best colour: stable soft water, dark background, plants, and low stress

Do not judge this fish only by bag colour or first-day colour. Their best appearance usually develops after they settle into a calm, mature aquarium.

Breeding

Blue Neon Rasbora breeding is not common in typical community aquariums. They are tiny egg-scattering fish and require excellent water stability, soft acidic conditions, very fine foods, and careful fry management.

This species is usually kept for display and rarity rather than easy breeding.

Canada-Wide Live Fish Shipping

Blue Neon Rasbora is available from Topick Aquarium in Canada when in stock. Local pickup is available in Markham, Ontario, and Canada-wide live fish shipping may be available depending on weather, route, and livestock condition.

Important Note

Blue Neon Rasbora is a delicate rare nano fish, not a beginner starter fish. It should be added to a mature, stable aquarium with peaceful tank mates and soft water conditions.

Customers with hard tap water, unstable new tanks, or active community fish should choose a more adaptable nano species first. For this fish, stability and low stress are more important than simply meeting a number on a test strip.

FAQ

What is Blue Neon Rasbora?
Blue Neon Rasbora is a rare nano schooling fish commonly sold as Sundadanio axelrodi. It is also known as Neon Blue Rasbora, Blue Axelrodi Rasbora, or Axelrod’s Rasbora.

What is the scientific name?
The scientific name commonly used in the aquarium trade is Sundadanio axelrodi. Older literature may refer to it as Rasbora axelrodi.

Is Blue Neon Rasbora beginner-friendly?
Not really. It is very small and sensitive, so it is better for aquarists with mature, stable, soft-water aquariums.

How many Blue Neon Rasboras should I keep?
We recommend at least 8–10, with 10 or more preferred. Larger groups feel safer, look better, and show more natural schooling behavior.

Can Blue Neon Rasbora live in tap water?
It depends on your tap water. This fish strongly prefers soft, stable, slightly acidic water. Hard or unstable tap water is not recommended without preparation.

Do Blue Neon Rasboras need blackwater?
They do best in soft, mature, planted or blackwater-style aquariums. Botanicals, driftwood, dark substrate, and floating plants can help reduce stress and improve colour.

Can Blue Neon Rasbora live with shrimp?
Yes, they can work with adult dwarf shrimp in peaceful planted tanks. Very tiny shrimplets may still be eaten, so shrimp-only tanks are better for maximum breeding.

Why are my Blue Neon Rasboras not very blue?
Colour depends on sex, stress, water conditions, lighting, tank background, and settling time. They often look best in stable soft water with dark contrast and plenty of plants.

What should I feed Blue Neon Rasboras?
Feed very small foods such as baby brine shrimp, cyclops, daphnia, micro pellets, crushed flakes, and powdered nano fish food.

Can Blue Neon Rasboras live with bettas?
We do not strongly recommend it. Some bettas may ignore them, but Blue Neon Rasboras are extremely small and can be intimidated or hunted by more assertive bettas.