Max Size: up to 3 cm

Neon Blue Rasbora (Sundadanio axelrodi)

The Blue Neon Rasbora is a peaceful, active and good looking schooling fish. These Rasboras make a great addition to planted aquariums with other small and peaceful species. It is not recommended to keep them with large, fast-moving species, or they will feel threatened, and worse, get eaten as they are so small. These fish do best when kept in groups of six or more. These fish are active and seem to enjoy areas with little flow as well as quieter spots.

The Blue Neon Rasbora needs specific water parameters a right environment and excellent water quality to thrive, so, therefore, are not recommended for the beginner aquarist.

The Blue Neon Rasbora has a glittery looking iridescent dark blue upper body, and a red mid-lower body and the rest of the body is transparent. The males have a black anal fin, and this usually goes a dark black when they are dominant. The fin looks somewhat odd and could be mistaken for fish waste hanging from the fish.

There are several colour varieties of this fish. These include copper-clear, neon-copper, neon-blue and neon-green.

Quick Facts
Scientific NameSundadanio axelrodi
Other NamesAxelrods Rasbora
OriginsSoutheast Asia
Aquarium LevelMiddle - Top
Best kept asGroups 6+
Lifespan2 - 5 years
Water Parameters
Water TypeFreshwater
Temperature73 - 79 ℉ (22.8 - 26.1 ℃)
PH4.0 - 6.5
GH2 - 5
Neon Blue Rasbora
Neon Blue Rasbora


Blue Neon Rasboras are endemic to the Greater Sunda Islands, Bangka Islands, and Riau Archipelago Islands of Sumatra and Borneo as well as West Kalimantan, Central Kalimantan and South Kalimantan provinces in Indonesia in Southeast Asia.

They inhabit black water pools and streams associated with aged forest peat swamps. The water is typically stained brown due to the release of tannins and other chemicals released by decomposing natural matter, and the substrate is covered with fallen twigs, leaves and branches.

Other Rasboras of interest

Black Line Rasbora(Rasbora borapetensis)
Chilli Rasbora(Boraras Brigittae)
Clown Rasbora(Rasbora kalochroma)
Exclamation Point Rasbora(Boraras urophthalmoides)
Fire Rasbora(Rasboroides Vaterifloris)
Glowlight Rasbora(Trigonostigma hengeli)
View All Rasboras

Diet & Feeding

Blue Neon Rasboras can be a little fussy and may not accept dried foods initially. However, they will learn to take them once they are settled into the aquarium. It would help if you always offered regular meals of small live or frozen foods such as daphnia, nauplii, artemia, and bloodworm so they can develop excellent colour and condition.

Sexual Dimorphism

It is relatively simple to distinguish males from female Blue Neon Rasboras. Males are much more colourful usually with more blue on the flanks, are noticeably slimmer than females and also exhibit dark colouration in the anal and ventral fins whereas females have a colourless anal fin.


Unfortunately, the Blue Neon Rasbora is very hard to breed and has not been bred much in the home aquarium. The reason for this is probably due to the fact it does not appreciate fluctuating water conditions, making it challenging to arrange separate spawning and rearing tanks.

Reports do exist, however, and the most significant successes have been when the adult fish are kept alone as a good-sized group in a heavily-planted, well-established aquarium.

The pH should ideally be relatively low with other parameters within the ranges suggested here, the most critical factor is that they remain stable.

The simulation of blackwater conditions using real peat fibre and leaves is thought to be extremely beneficial due to the microorganisms which increase in such set-ups.

It is better to avoid bright lighting, and it is essential to feed the fish with plenty of live and frozen foods, this will help to induce spawning.

If your aquarium contains the necessary balance between water conditions, cover and microfauna, then fry should start to appear without further intervention.

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Date Added: 29/10/2020 - Updated: 14/07/2021 13:01:07