Neon Blue Rasbora: Care, Size, Tank Size & Tank Mates


Neon Blue Rasbora (Sundadanio Axelrodi) is also known as Blue Axelrodi Rasbora, and they are a type of Rasbora fish. These fish only reach 1 inch (2.5cm) in size, so they are well-suited for nano tanks. Compared to other popular fish in the aquarium hobby, Neon Blue Rasbora are quite rare.

Neon Blue Rasbora originate from the Greater Sunda Islands of Borneo and Sumatra. They are occasionally found in the Riau Archipelago and Bangka Island off the east coast of Sumatra as well. Within these regions, they inhabit black water streams, pools, and swamps that consist of aged forest peat. Their native habitats are currently under threat due to rubber and palm oil plantations, building development, and various other human activities.

These fish have amazing colors of blue, green, and red. The top half of their body is a shade of bright iridescent blue. The mid-lower part of their body is usually a reddish-copper color, and the rest of their body is quite transparent and clear.

The male Neon Blue Rasbora is brighter coloration and slimmer body compared to the female fish. The males have a black anal fin as well, which tend to be darker if it is a dominant male.

Another interesting trait of the male Neon Blue Rasbora is that they have are able to produce a small croaking or chirping sound when stressed. For example, they may make this sound when taken out of the water. The males croak when they are battling each other for dominance as well.

neon blue rasbora
Neon Blue Rasbora (Sundadanio axelrodi)

Neon Blue Rasbora Care

Neon Blue Rasbora is not difficult to take care of, but they aren’t the hardiest fish in the aquarium hobby either. Therefore, these fish aren’t recommended for beginners. They do have specific requirements regarding their water parameter such as temperature, pH level, and water hardness.

First, these fish are schooling fish that do best in a group of 6 or more. In fact, a large group of 20 to 30 fish would be ideal. Since they are small fish, they are able to thrive even in nano tanks. The minimum tank size for Neon Blue Rasbora is 10 gallons. For a 10 gallon aquarium, a group of approximately 10 fish can be kept together. If you wish to keep a larger school of fish, a larger tank such as a 20 gallon or 30 gallon tank would be necessary.

Next, regarding the water parameters for Neon Blue Rasboras, it should resemble their habitat in the wild as much as possible. Since they are native to blackwater biotopes, they prefer low pH environments. The ideal pH range for these fish is 4.0-6.5. Regarding the water hardness, they prefer relatively soft water ranging from 0 dGH to 5 dGH. The ideal temperature range is between 73°F and 79°F.

Lastly, regarding the tank setup for Neon Blue Rasboras, this should resemble their native habitat as well. Their native habitat in the wild would consist of plenty of submerged plants, floating plants, and driftwood. The submerged plants create a lot of hiding places for the fish. To mimic these environments, aquarium plants such as java fern, java moss and cryptocorynes can be planted. The floating plants benefit the fish by creating shade as well. They dislike strong light, so the settings on the aquarium light should be adjusted accordingly.

As the driftwood and leaves decompose in the water, it stains the water and gives off tannins. Eventually, it creates a blackwater biotope with soft water. To create a similar environment in an aquarium, dried leaf from beech, oak, and almond can be used. Indian Almond Leaves (Terminalia catappa) are quite popular in the aquarium hobby as well.

Behavior and Tank Mates

The neon blue rasbora are very peaceful and active fish but tend to dominate and disrupt the peace of the other fish that are in a tank that is too small for them all. They do great when placed with other species that are peaceful and about the same size as them. When put in the tank with fish larger than them, they will feel threatened, become timid and can possibly get eaten. Because of this, do not add your neon blue rasbora to any community tank. Instead, add them to a tank with other rasbora species such as the Phoenix rasbora.

Another fish that would do great with the neon blue rasbora are bettas! In the wild, bettas and rasboras coexist. They both originate from South Asia and live in slow moving water, rice paddies and river basins. Since they come from the same habitat, they both enjoy and need the same requirements for their water in the tank. This makes it easy to add them to the same tank and without any issues. If you don’t know where to start when deciding what type of fish to introduce to the neon blue rasbora, start with bettas as they would be perfect companions!

Food & Diet

This small fish can be somewhat picky when it comes to food. They are omnivores and they might not accept dry food to start with but will slowly accept it as they adjust to their new tank. In the wild, the neon blue rasbora eat aquatic animals such as crustaceans, worms, insect larvae and other zooplankton. In the tank, neon blue rasbora enjoy eating small live or frozen foods. They are comfortable eating daphnia, bloodworms, artemia and nauplii. Feeding your fish high quality foods will improve their beautiful colors and make them look brighter! When feeding the neon blue rasbora, you will notice that they only eat a little bit of food and then stop, whereas most fish just keep eating and eating. These fish are light eaters, and they are small so they don’t eat a lot of food at a time.

Breeding Neon Blue Rasbora

Though it has been done before, there are very few times that neon blue rasbora have been bred in home aquariums. This is due to the fact that they do not enjoy the fluctuation of the water of the tank. This makes it difficult to set up separate spawning tanks, and the neon blue rasbora don’t like being handled anyway. Aquarists do find success in breeding these fish by keeping the adults alone in a group of at least 6 fish. The tank should be established with the perfect water conditions as well as heavily planted. The components of the water that are stated above should remain stable, with a pH level below 6.0, temperature between 73°F and 79°F, and the hardness level below 5 dGH. If any of these are out of range, you will most likely not have success when attempting to breed your neon blue rasbora. Make sure the tank has very limited lighting since the fish do not enjoy it. Feeding the neon blue rasbora plenty of lives do frozen foods will encourage the fish to begin spawning. In simple terms, the fish must feel as if they are in the wild in order to breed with one another. The neon blue rasbora must feel the most comfortable possible or there wont be success in breeding. If all the requisites mentioned above are met, you are sure to see spawning and small fry appearing in the tank.

Fish Laboratory

With decades of collective fishkeeping experience, we are happy to share the fish care tips that we've picked up along the way. Our goal at Fish Laboratory is to keep publishing accurate content to help fishkeepers keep their fish and aquarium healthy.

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