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Maximum size : 3 cm

Neon Blue Rasbora - Sundadanio axelrodi : Complete Fish Profile & Care Guide

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The Blue Neon Rasbora (Sundadanio axelrodi) is a stunningly vibrant species that can be a joy to watch in an aquarium setting. Despite their size, these fish are full of personality and make for an excellent addition to a peaceful community aquarium. However, they are not recommended for beginners due to their specific care requirements. To keep them happy and healthy, it is crucial to maintain their water parameters and environment carefully. The Blue Neon Rasbora boasts a dark blue upper body that shimmers with iridescence, which gradually transitions to a fiery red mid-lower body. The rest of the body is transparent, which only further emphasizes the electric blue hue. The males exhibit a black anal fin that will darken when they are dominant, although it can look peculiar and might be mistaken for fish waste. There are several colour variations available, including neon-copper, neon-blue, neon-green, and copper-clear. These variations add an extra layer of visual appeal to these already captivating fish..

Neon Blue Rasbora Photos

Sexual Dimorphism

Distinguishing between male and female Blue Neon Rasboras is a straightforward process. Males possess more vibrant and extensive blue coloration on their flanks and exhibit a slimmer body when compared to their female counterparts. Additionally, males possess a dark pigmentation in their anal and ventral fins, while females have a colorless anal fin.

Quick Facts

Scientific NameSundadanio axelrodi
Year Described1976
Other NamesAxelrods Rasbora
Max Size3 cm
Aquarium LevelMiddle - Top
Best kept asGroups 6+
Lifespan2 - 5 years

Water Parameters

Water TypeFreshwater
PH4.0 - 6.5
GH2 - 5
73 - 79
22.8 - 26.1

Natural Habitat

The Blue Neon Rasbora is a small but captivating fish native to the lush, verdant forests of Indonesia. These fish thrive in black water habitats with soft, acidic water and a rich organic substrate. You can find them in 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. They inhabit tranquil pools and streams where the water is stained with tannins and other natural compounds released by decaying organic matter, providing shelter and sustenance for these remarkable creatures.


Regrettably, breeding the Blue Neon Rasbora in the home aquarium setting is notoriously challenging and has seen limited success. This is primarily due to the species' sensitivity to unstable water conditions, which makes creating suitable separate spawning and rearing tanks a difficult task. However, some reports do exist of successful breeding, and it has been noted that keeping adult fish as a good-sized group in a heavily-planted, well-established aquarium is the best approach. Stable water parameters are critical, with a relatively low pH being ideal. Simulating blackwater conditions with real peat fiber and leaves is also believed to be highly beneficial, as it encourages the growth of microorganisms that the fish require. Bright lighting should be avoided, and it is essential to provide the fish with plenty of live and frozen foods to induce spawning. If the aquarium maintains the necessary balance between water conditions, cover, and microfauna, fry should begin to appear without any additional intervention.

Diet & feeding

Blue Neon Rasboras may require some patience when it comes to feeding as they can be finicky at first and may not accept dried foods. However, with time and patience, they will learn to take them. For optimal color and health, it is recommended to offer regular meals of small live or frozen foods such as daphnia, nauplii, artemia, and bloodworms.

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