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


Neon Blue Rasbora (Sundadanio Axelrodi) are small aquarium fish that are great for nano tanks. Having an aquarium is very exciting and can even be beneficial for one’s health and wellbeing. Studies show that fish are the third most popular pet, with about 13 million Americans having them as pets in their own homes. Having fish as pets can help reduce stress, improve sleep, decrease anxiety and even improve focus and creativity. You don’t need a large aquarium, a small sized tank will do just fine. A small tank may not hold a lot of fish, but it can be beneficial since it doesn’t take up a lot of space. Anyone can find a spot for a small tank! One of the many options of amazing fish to add into a small (or large) tank is the neon blue rasbora. Its scientific name is sundadanio axelrodi, and it would make the perfect addition to any tank.

Neon Blue Rasbora Care

The neon blue rasbora is a tiny fish that originates from the Greater Sunda Islands of Borneo and Sumatra. It is also occasionally found in the Riau Archipelago and Bangka Island off the east coast of Sumatra. This fish grows to be only 3cm in length as a full grown adult. The habitat of the neon blue rasbora are black water streams and pools associated with aged forest peat swamps. These tiny fish are rarely seen in shops and are hard to come by. Their habitats are currently under threat due to rubber and palm oil plantations, building development, and various other human activities.

These tiny fish are stunning, with the top half of their body 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 tend to have a black anal fin that sometimes gets even darker when the fish is dominant. The color of the male fish is brighter and more vibrant than that of the female fish, and the body of the male fish is also slimmer than that of the female. An interesting fact about this fish is that the males have a certain body structure that allows them to produce small croaking and chirping sounds when stressed. They croak during dominance battles against other males, and at times they may croak or chirp when taken out of the water.

neon blue rasbora
Neon Blue Rasbora (Sundadanio axelrodi)

Tank and Water Specifications

The neon blue rasbora is not recommended for beginner aquarists due to the specific details needed for the tank and water. The three most important components for the water of the tank are the temperature, the pH level and the hardness level of the water. These three components are crucial for the survival of the fish. Unlike other fish, the threshold between the minimum and maximum levels of these components is much smaller, making it a bit more difficult to keep the fish’s needs in range.

The new home for this fish needs to resemble its wild habitat as best as possible. The neon blue rasbora is a schooling fish. Due to that, they do best in groups of 6 or more. A tank the size of 12 gallons is a great place to start and will be perfect for a small group of fish. These fish also do well in large groups of 20 to 30 fish. If you are planning on having a large amount of fish, be sure to buy a large tank of 30 gallons or more. Because of its wild habitat, it seems as though it would do best in a biotope type of display. To start, the water for the tank should be black water and the temperature for the water of the tank should be between 73°F and 79°F. The pH needs to be strictly acidic, with pH levels between 4.0 and 6.5. The neon blue rasbora enjoy soft water, so the level of hardness for the water should stay low between 0 dGH and 5 dGH.

In order to imitate the neon blue rasbora’s habitat in the wild, be sure to add plenty of plants into the tank to create lots of shaded areas. Floating plants will help block some light from coming into the tank, as well as driftwood roots and branches. All of the plants and wood added will decompose and stain the water in order to give it that black water affect. Leaf litter and tannins will help soften the water to the fish’s liking. Adding dried leaf litter such as beech, oak and almond leaves will also enhance the natural feel of the tank and will be more pleasant for the neon blue rasbora. A few aquatic plants that would be a great addition to the home of these fish are java fern, java moss and cryptocorynes.

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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