Dwarf Neon Rainbowfish – A Complete Care Guide


Introduction to the Dwarf Neon Rainbowfish

Dwarf Neon Rainbowfish are a small variant of the rainbowfish family and belong to the species Melanotaenia Praecox. Most specimens you will find online and in local fish stores were bred in captivity. Still, they are native to New Guinea, Indonesia, and Australia. They are usually not found in big box pet stores that carry fish, but you may be able to find them in your local dedicated fish store.

They are readily available in most online fish stores but come with the added cost of shipping. While they are not necessarily rare, they are a little more expensive, coming in at approximately twelve to fourteen dollars. When well cared for and fed a high-quality, varied diet, they will live between three and five years.


Juvenile Male and Female

Males and females are easily distinguishable in the Dwarf Neon Rainbowfish. While they are much less colorful as juveniles (see picture above), adult males have brilliant scales that are predominantly blue, but it is not uncommon to see some green in their shimmering scales. They can strikingly contrasting red fins and big blue eyes. Their bodies are slender when viewed head-on, tall, round, and flat when viewed from the side.

Adult females are less brightly colored but still quite lovely. They have light blue scales that shimmer with iridescent bands of green and pink, with blue eyes. Their fins are not as striking in contrast as their male counterparts but have yellow to reddish-orange tips. Their bodies are smaller and less circular than males. It is easy to tell when they are ready to mate, as their already brilliant bodies increase sharply in color and the female’s body looks noticeably plumper.

Expect males to grow between 2.5-3 inches and 2-2.5 inches for females.

Behavior and Temperament

The primary way I would describe the personality of these fish is: highly intelligent. They are very interactive with people and other things both inside and outside the tank. Very lively and curious little fish, they make an excellent pet for the home aquarium. You can keep them in a stunning species only tank, as centerpiece fish in a medium-sized community tank, or as background players in large community tanks.

No matter what kind of tank you have, these little fish’ personality will shine just as brightly as their colors.



Dwarf Neon Rainbowfish generally do quite well with their own kind, as long as there are several of them together. Dominant males may attack or kill other males during breeding time. This is why you should have as many as possible in your tank to spread aggression. This way, no one male will be singled out as the “bottom dog” and get harassed to the point of death.

They are generally peaceful with their own kind and community fish of similar size. I love keeping species of danio with rainbowfish. They are the same general size, very active swimmers, and come in a variety of colors. There are a number of danios that will compliment Dwarf Neon Rainbowfish. They are very common in the aquarium keeping hobby so you should be able to find them at nearly any fish store, whether in person or online.

Another fantastic option to keep with Dwarf Neon Rainbowfish are bottom feeders. Since these blue beauties almost never venture down in the aquarium depths, there is nearly always uneaten food that slips by them down to the bottom. Rather than have to worry about that later, employ a cleanup crew! They may eat small shrimp and fry, but their mouths and throat passages are too small to be much of a threat to larger shrimp, like Amano and bamboo shrimp. Full-grown species of dwarf shrimp will usually be safe as well. 

If you are not keen on keeping shrimp, there are many other bottom feeders you might be drawn to. I find loaches to be a fantastic option. They come in a wide variety of colors and shapes. They can be a little aggressive, but since they rarely leave the bottom and rainbowfish rarely leave the top, you should have little trouble if your tank is large enough.

My favorite are Skunk Loaches (pictured above). They are relatively timid as loaches go, but I find their little black skunk stipe to be incredibly cute, and their little bristly noses are very entertaining to watch. Make sure you use sand as a substrate if you plan to keep loaches. Their bodies are delicate and prone to scratches from coarse gravel. They also appreciate caves and rock crevices to hide in if their feeling stressed.

The above are just a few options. There are tons of fish that would be great with Dwarf Neon Rainbowfish. If nothing above has caught your attention, try looking into common fish such as platies, mollies, tetras, and rasboras. Pearl Guaramis grow to about the same size, and their pearlescent swirls would be a great contrast to the electric blue of the rainbowfish. I have heard of some aquarists that successfully keep their Dwarf Neon Rainbowfish with Discus!

However, I would only recommend trying this if you are a very experienced aquarist, as Discus Fish are notoriously difficult to care for. And of course, the peaceful pleco is rarely out of place in the community tank (make sure you pick a dwarf variety if your tank is on the smaller side – non-dwarf varieties will quickly outgrow it!).


Breeding this lovely species is relatively simple as long as you stick to some general guidelines. However, it can be somewhat tricky to raise the fry. As mentioned before, it will become evident when your fish are ready to mate. The female will become much fuller and rounder, while the males will become more brightly colored.

You will also notice the males will almost continually flashing back and forth in front of the others in what is called ‘displaying.’ Displaying is done to both show off their genes to available females and warn other males away. They will also become very territorial with other males and often fight, sometimes to the point of death.

Once you see these behaviors persist for a few days, pick one male and one female that seem to be the healthiest, plumpest, and the best colored of your group. For best results, you should have a breeding tank ready for them contains water with a neutral pH of about 7. The temperature in this tank will be on the higher end of their normal tolerance range, at about 78-80° F 

 All that is needed in this tank is a small filter and air pump with a low flow. The eggs and fry are minute, so a strong water flow is detrimental to them. The only other things in the tank should be moss-type plants, plants with long, thin leaves, or ‘breeding mops’ purchased specifically for spawning. DO NOT use substrate in this tank. The eggs will easily get lost in all the nooks and crannies. The eggs will be attached to these by tiny, thin threads. The pair will spawn for several weeks, laying many batches of eggs. The adults are known to eat their young, so make sure you have another tank set up to raise the fry.

As soon as you notice when eggs have been produced, introduce them to the tank set you have set aside to raise them. Even for fish fry, newly hatched Dwarf Rainbowfish are absurdly small. They are so little that even freshly hatched baby brine shrimp, a staple food for most freshwater fish fry, are too large for them.

For the first several days of life, you should mix artificial plankton rotifers into the water. I have heard some aquarists have had luck with micro worms, but I like to stick to powdered APR. After several days, they should be moved to a diet of baby brine shrimp. Never feed these fry anything that will sink, as they are always at the very top of the aquarium, and sinking food will be wasted and spoil the water.



If you do not plan to breed them, Dwarf Neon Rainbowfish are relatively straightforward to care for. I do not specifically recommend them to beginner aquarists because they are somewhat sensitive to pH levels. But, as long as you are confident in your skill in this area, they should give you no trouble. Their preferred pH level should be kept between 6.8 – 7.5, although they like the lower levels when breeding.

Their tank size should be an absolute minimum of 20 gallons. I would only recommend this size for a group of six, which is the smallest group they will feel comfortable in. A group of at least 10 – 12 is good and even more is excellent. Of course, you will need to get at least a 40 – 55-gallon tank with that many fish. Make sure to get an even number of males and females. With several specimens and an even split of the sexes, the male’s aggression and competitiveness will be lessened. No one male will be singled out for torment.

Dwarf Neon Rainbowfish prefer a tank that resembles their native habitats in New Guinea, Indonesia, and Australia. This means they will need warm water in a heavily planted tank. Dense foliage helps to break up the tank into different territories the males can use to attract a mate and defend against other males. They also appreciate a heavy amount of floating plants to make them feel safe against attacks from above. They enjoy a moderate water flow and plenty of open space to swim and explore. 

They generally occupy the middle and upper levels of the tank and rarely venture down to the bottom. For this reason, take special care when vacuuming your gravel to remove any uneaten food that has settled in the substrate. A dark-colored substrate is their preference. It makes them more comfortable, and comfortable fish show their best colors. Additionally, their bright bodies and fins show remarkably well against dark colors.

They will readily accept any high-quality flaked and freeze-dried foods, but this should not be their only source of sustenance. With their bright, inquisitive minds and extra active lifestyle, they need more than just flakes to remain happy and healthy. Try supplementing their diet with meaty live and frozen foods.

They are quite happy with a wide range of temperatures. They do well with temperatures anywhere from 72° – 82° F. The higher end of this range can encourage spawning, and if you care to breed them, the spawning tank should be kept on the higher end of this scale. 

Is the Dwarf Neon Rainbow Right for You?

The first question I would ask someone if they posed me this question is: Is this your first aquarium? If the answer is yes, I would not recommend the Dwarf Neon Rainbowfish for you. If you have already successfully kept a tank or two for at least a year with no major disasters, then I would say yes. These beautiful fish with the sapphire and ruby bodies and their extreme curiosity and intellect make for fantastic pets.

Whether you are looking for them to be background players in a huge community tank or be the centerpiece for a small aquarium, they will make fantastic pets for anyone with at least a little fishkeeping experience.

However, there are some things you should keep in mind before adding the Dwarf Neon Rainbowfish to the home aquarium:

  1. They are sensitive to pH levels.
  2. Males can be very aggressive with each other, so have a large enough tank and enough individuals to spread the aggression.
  3. They rarely eat off the bottom of the tank, so be sure to keep it clean or have a handy cleanup crew.
  4. If you plan to breed them, you will need two additional tanks, one for spawning and one to raise the fry in order to keep the adults from eating the babies.


Dwarf Neon Rainbowfish are a beautiful and gorgeous fish for the home aquarium. They’re sensitive to pH levels and can be aggressive, but they can be a staggeringly beautiful addition to any home aquarium. For those who’re looking to setup community aquariums, they can be a unique and colorful addition.

For advanced aquarists, we recommend trying your hand at breeding. It can be a fun and unique challenge and incredibly rewarding. It can teach you more about your aquatic pets. Let us know if you have any questions, pictures of your fish, or anything else in the comments below.

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