April 6

Celestial Pearl Danio Habitat, Behaviour and Breeding Information


Celestial pearl danios are smallish, brightly colored cyprinids that are native to Southeast Asian waters. They do not exhibit any form of aggressive behavior, and they love to swim about in a shoal.

They can only grow to a maximum length of about 2.5cm which makes a nano tank ideal for them. They thrive in a tank with a slow flow rate, and their tank should be equipped with plants and other items that make up their hiding spots.

They may be small, but they are never inconsequential within the aquarium. For one, they are pretty colorful and very active. So, there isn’t a dull moment with them in the tank.

Their behavioral pattern, feeding habit, lifestyle, and tank mates are extensively discussed in this article. Again, you will get to learn about a few care tips and how you can breed them in the home aquarium.


Scientifically known as Celestichthys margaritatus, the Celestial Pearl Danio or Galaxy Rasbora is an absolutely beautiful pint-sized fish that was first revealed by Thai aquarist Kamphol Udomritthiruj in 2006.  Since then, it became very popular and has been given various names.

Celestial Pearl Danio

Habitat and Distribution

This remarkable breed of fish is found in small, shallow, and thickly planted ponds in South East Asia. The species was first discovered in a small plant-laden spring-fed pond in Hopong Village, Burma. In their natural habitat, you can find Celestial Pearl Danio only in small ponds in the mountainous areas in the villages around Hopong, about 1040m above the sea level in the north of Myanmar. The areas are mostly grassland with abundant sunlight filled and rich quality aquatic plants.

The temperature of the water where the species is found is 95 degrees F in summers and almost freezing during the winters. The place in Hopong from where the fish was discovered was prohibited for the westerners for several years and later many other species were discovered from the same area. Since then, these fishes gave been found in waters linked with the Salween River all over Southern Shan and across the Northern Thailand border.

In 2007, because of overfishing, the species was on the verge of extinction. As the breeding is easy, aquarists got the species bred in tank conditions, and fishing in the wild was no more required.

Physical features

You will fall in love with the heavenly charm of these fishes which have exquisite colors all over their body, adorned with pearl-like spots on the sides and gorgeous red fins. A group of Celestial Pearl Danio can bring life to any backdrop. What makes these fishes stand out is the coloration of their fins which have two parallel lines of red or orange depending on their sex.


The males of this species are thin and more vibrant in color. They have an overall deep midnight blue color; the pearlescent spots are arranged in a series that is clearly visible on the flanks. They also have bright red stripes on the fins and red belly. You can see a unique flash of the red stripe on the back of the males which runs all the way from the head to the dorsal fin.


When gravid, the females get rounder and bigger in shape. They are a little light in color as compared to their male counterparts with a golden blue sheen. In females, the pearlescent spots aren’t that bright and fins are in a blanched shade of orange. Few females develop an orange color in the belly. It is said that females develop a dark spot in front of the anal fin at the beginning of spawning.

The fishes in general have a strange body shape with their body length about three times more than their height. The gill plates are almost transparent and you can see the blood vessels through them. It is because of this notable difference in the colors of both males and females that male fishes are given preference while people are buying them for their tanks. However, having all-male fishes in the tank can result in a fight between them, so it is advised to have an equal proportion of both males and females in the aquarium.


Celestial Pearl Danio has a lifespan of 3-5 years in stable aquariums.

Standard Length

This species of fish is a maximum of 1 inch from head to tail in size.

    Behavior and Compatibility

    This species of fishes live in groups, so you can keep 6-7 fishes which will keep them active. Very demure and peaceful in nature, these fishes work in harmony with communities that have similarities in their behavior pattern such as Mollies, Killifish, Tetras, and Guppies. Having fishes from the same species or origin would also be a great idea as they have almost the same behavior pattern.

    These fishes are said to show great compatibility with Neon Tetras which stay on the upper area of water. Celestial Pearl Danios co-reside with many other species which makes them ideal for the peaceful community aquarium.

    In case if you decide on having various schooling species, then your tank would need more water per fish. It is better to have these fishes in company with equal-sized species to reduce their shyness. With bigger more aggressive species; Celestial Pearl Danio will get intimidated and outcompeted for food.

    Males spend most of the time courting the females and sparring with rival males. The fight between males is nothing to worry about, it is mostly ritualized and the weaker males don’t get harmed if they simply swim away.

    However, dominant males can harm weaker ones with their teeth if they cannot get away from the fight. If a lot of males are there then it would be advisable to keep them in a bigger tank with a lot of plants to avoid fights. By having plants in the tank, the male fishes will have a good hiding place when they are competing for females.

    Also, it is noted that these fishes have the tendency to eat juvenile shrimp, so it would be better to have adult shrimp in the tank.


    Galaxy Rasbora fishes are omnivores and prey on smaller critters. In the wild, they eat small spineless species, zooplankton, worms, and small invertebrates. These fishes have small mouths and pharyngeal teeth. In the aquarium, these fishes can eat dry food which is small in size to fit their mouth such as some premium quality flakes. As these like to stay in the bottom of the tank, and rarely swim up to the surface, it would be better to give them food that can sink instead of floating.

    You can also, give them small frozen food like daphnia, moina, brine shrimp, small tubifex, small white worms, and dried krill which can also help with the coloration of the fins and encourage spawning.

    Make sure to give them different types of food instead of repeating the same, which will make them more vibrant. Also, observe the fishes see if some of them are not getting competed for food. This will help in maintaining the longevity of their lives; you can feed the more dominant fishes on one side and shy ones on the other.


    Aquarists Pete Liptrot and Paul Dixon of the Bolton Museum Aquarium, U.K were the first to successfully breed these fishes. These fishes spawn every day whether it is in their natural habitat or in the aquarium.

    The sex of the fishes is so easy to distinguish that breeding is not difficult at all. Celestial Pearl Danio becomes reproduction at the age of three months. You can simply look for fish that is bigger in size and has a round belly. These female fishes will also have a notable darker color. If the female fishes are in a nice condition, then they will spawn more often in a nicely planted aquarium.

    In one tank, it is best to introduce a single pair or two males and several females. Although, the higher number of males will increase the risk of egg predation and more competition among each other. For a spawning session, males hover over a clump of plants with their body with a head-down angle at the bottom and females swim over to them and initiate the spawning. The pairs do not form any bond and can spawn with multiple mates. For breeding, it is best to use just a single pair in a tank and remove them when spawning is over as they can eat the available eggs.

    Nicely conditioned fishes can up to 30 eggs at a time in a single spawning event and they lay eggs where the water movement is low to medium. As discussed previously, feeding them live food will stimulate early spawning.  If you want the females to lay more eggs then you can nourish the aquarium with the necessary pH and temperature. There should be fine wool mops or some other fine-leaved plant in the tank.

    As the males are ravenous egg eaters and will seek scattered eggs; if you see the eggs, transfer them into a breeding tank. You can use a spawning grate such as a plastic needlepoint canvas to separate the eggs from the aggressive males. These eggs will take 72 hours to incubate and later they get into the larval stage where they start swimming.

    The newly hatched fry is dark in color and lies at the bottom of the tank. Initially, they do not move much and start swimming only after a couple of days. After some time, they lose their dark color and get a faded silver tone.

    In the breeding tank, feed the fishes micro foods at the beginning like paramecia and after about a week, you can start giving live food such as newly hatched brine shrimp, once the fry is large enough to accept them. The growth of this species is pretty rapid; they take on adult coloration and size in about 10 weeks and reach the adult size at the 14th week. You can start breeding the next generation at 11-12 weeks of age.


    It is very important to keep an eye on the males courting females from the beginning as they spend most of the time doing that and fight with other males for potential mates.

    You can observe any torn fins or bite marks on the sides of the fishes. This not only harms the fishes but also leads to fin rot. The fin rot can also be caused by poor quality water in the aquarium and there are many ways to prevent it from happening. Make sure to keep the condition of the tank optimal for the fishes by maintaining the proper pH and temperature of the water.

    You can cure or avoid fin rot by changing water more frequently and using anti-bacterial medications.

    Aquarium requirements

    In their natural environment, these fishes reside in small ponds which are alkaline and have a temperature of above 24 degrees Celsius. However, as the water is shallow, the temperature keeps changing and the fishes have got adapted to it.

    For an aquarium, the Celestial Pearl Danio is an incredibly timid fish that can become adaptable to a new environment pretty easily. To create a good living arrangement for them, including a lot of plants with a dark substrate in the tank. Lack of plantation will make the fishes edgy and uncomfortable which will lead to them hiding all the time. With a large number of plants, these fishes will exhibit their natural behavior. With a large tank with up to 10 gallons of water, males have plenty of space to move around and avoid fighting. For breeding purposes, do not keep this species with other fishes or shrimps. However, for display, you can introduce other compatible species to these fishes.

    Here are some basic requirements for the aquarium in order to keep these fishes:

    • Water should medium-hard and a pH of around 7 or a little high.
    • Regular filtration is required for the water to make sure that it is clean.
    • Tank temperature should be 22-24 degrees Celsius, with extremely high temperature, the fishes may die.
    • Provide bright lighting as the fishes originate from sunlit ponds. You can use the LED light as long as it doesn’t get too much.
    • You can also use some floating plants as if the aquarium is fully covered with plants, you wouldn’t be able to see the fishes properly.
    • Do not keep large aggressive fishes with this species; you can instead introduce adult shrimps in the tank. The fish is friendly with similar-sized species of other fishes.
    • While breeding, you can only have males and females of the same species in the tank.
    • These fish prefer slow or medium-moving water.
    • You should also have a lot of rocks, almond leaf litter, and driftwood to provide them a natural-looking environment.
    • Keep the tank relatively shallow which will mimic the nature of their native habitat.

    This is a calm fish breed that is not demanding and can settle in small tanks. Still, it requires a stable condition and some maintenance. Their dynamic colors and grouping nature brings life to any aquarium. As it is a less complicated breed of fishes, it is good for beginners to build knowledge.


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