The celestial pearl danio (Danio margaritatus), often referred to as the Galaxy Rasbora or simply CPD, is a strikingly beautiful fish that has captivated aquarium enthusiasts since its introduction to the hobby. Discovered and officially described only in 2006, this small, vividly colored fish has quickly become a favorite among fishkeepers.
Native to Myanmar, the celestial pearl danio is renowned for its dazzling appearance. It features a unique combination of iridescent blue and bright orange spots that create a celestial effect, resembling a galaxy of stars. Its compact size, typically reaching just about 1 inch (2.5 cm) in length, makes it an ideal addition to smaller aquariums.
In addition to its visual appeal, the celestial pearl danio is appreciated for its peaceful and social nature. It thrives in well-maintained aquariums where it can be kept in schools of at least six individuals, allowing its natural behavior to shine. The species is relatively easy to care for, adapting well to a variety of water conditions and dietary options.
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Habitat in the wild
The celestial pearl danio (Danio margaritatus), belonging to the family Cyprinidae and the genus Danio, is a captivating fish with a relatively recent discovery. Native to Myanmar, this species is found in a restricted area to the east of Inle Lake, specifically within the Nam Lang and Nam Pawn river basins, tributaries of the Salween River. The celestial pearl danio thrives in shallow, densely vegetated lakes at elevations exceeding 1,000 meters above sea level.
This species was first documented in August 2006 in a lake near Hopong village, a region that had seen limited European exploration. The celestial pearl danio quickly gained attention in the aquarium trade, initially marketed under names such as Microrasbora sp. “Galaxy” or “Galaxy Rasbora.” The fish’s initial high price soon dropped as more specimens were exported.
However, by February 2007, overfishing had drastically reduced the wild population of celestial pearl danios, leading Myanmar’s Department of Fisheries to impose an export ban. The combination of its limited natural range and high demand had put significant pressure on the species. This led to increased conservation efforts, including the establishment of protected areas and the development of captive breeding programs to ensure the species’ survival.
Fortunately, celestial pearl danios have been successfully bred in captivity, reducing the need for wild collection. This success has also led to the discovery of five additional habitats for the species. Nevertheless, the celestial pearl danio’s story underscores the importance of responsible aquarium trade practices and effective conservation measures to protect vulnerable species from extinction.
Description
Color
Despite its small size, the celestial pearl danio (Danio margaritatus) is renowned for its stunning colors and captivating appearance, which make it a favorite among fishkeepers. This fish boasts a body color that ranges from dark blue to black, adorned with scattered white, golden, or orange spots that sometimes form small stripes. Its dorsal and anal fins are rounded, while its caudal fin is notably claw-ended. The abdominal fins are transparent with striking red edges, adding to its vibrant display.
Adult male celestial pearl danios exhibit more intense colors compared to females. Males have a reddish abdomen and a brighter overall coloration, with a fully colored dark blue body and bright red fins reserved for dominant alpha males. In contrast, females are generally paler, with a yellowish abdomen and almost colorless, transparent abdominal fins. The intensity of the colors in both males and females can vary depending on their mood and social status within the school.
Young males also display vivid breeding colors, especially during interactions with females. Unique among many fish species, the celestial pearl danio exhibits a distinctive swimming style. They often remain in their shelters or search for food with a sideways, slightly tilted motion. When they need to swim quickly to catch food or display aggression towards rival males, they rapidly spread their fins to assert their dominance.
This combination of striking coloration and intriguing behavior makes the celestial pearl danio a remarkable addition to any aquarium.
Size
The celestial pearl danio is a notably small fish, typically growing to a maximum length of just 1 centimeter (0.8 inches). This petite size makes it one of the smallest fish species commonly kept in aquariums, adding to its charm and appeal for fish enthusiasts.
Lifespan
Danio margaritatus typically has a relatively short lifespan, averaging up to 2 years. However, with proper care and optimal conditions, some individuals can live up to 3 years or even longer. Lifespan can vary based on factors such as water quality, diet, genetics, and the overall care provided.
| Characteristic | Description |
|---|---|
| Scientific Name | Danio margaritatus |
| Common Names | Celestial Pearl Danio, Galaxy Rasbora, Celestial Pearlfish, galaxy danio |
| Native Range | Myanmar (formerly Burma) in Southeast Asia |
| Habitat | Shallow, slow-moving streams and ponds |
| Maximum Size | Up to 2 centimeters (0.8 inches) in length |
| Body Shape | Slender and elongated with a slightly compressed body |
| Coloration | Metallic blue-green body with vibrant red and white markings |
| Fins | Dorsal and anal fins are elongated, while the caudal fin is forked |
| Temperament | Generally peaceful, but may display aggression during breeding |
| Water Parameters | Temperature: 22-26°C (72-79°F), pH: 6.5-7.5, water hardness: 5-15 dGH |
| Feeding | Omnivorous, will accept a variety of small foods, including flakes, pellets, and live/frozen foods |
| Breeding | Egg scatterers, breed in dense vegetation with a preferred water temperature around 24°C (75°F) |
| Conservation Status | Species of concern, subject to habitat degradation and overcollection |
Pearl danio vs celestial pearl danio
The terms “Pearl Danio” and “Celestial Pearl Danio” are often used interchangeably or confused with each other. However, they refer to two distinct species of fish. Below is a comparison table highlighting key differences between the pearl danio (Danio albolineatus) and the celestial pearl danio (Danio margaritatus):
| Characteristic | Pearl Danio (Danio albolineatus) | Celestial Pearl Danio (Danio margaritatus) |
|---|---|---|
| Common Names | Pearl Danio | Celestial Pearl Danio, Galaxy Rasbora |
| Native Range | Sumatra, Myanmar, and Thailand and Vietnam | Myanmar (formerly Burma) |
| Adult Size | Up to 2.6 inches (6.5 cm) | Up to 2 centimeters (0.8 inches) |
| Body Color | Silver body and two light yellow/white or blue/red stripes. It has an iridescent look. | Metallic blue-green with red and white markings |
| Temperament | Peaceful | Peaceful |
| Water Parameters | Temperature: 68–77 °F (20–25 °C), pH: 6.0-8.0 | Temperature: 22-26°C (72-79°F), pH: 6.5-7.5 |
| Water Hardness | Soft to moderately hard (5-19 dGH) | Soft to moderately hard (5-15 dGH) |
| Compatibility | Peaceful community fish | Peaceful community fish |
Difficulties in keeping
This is a small peaceful fish, that became very popular due to these features. The may reason you may want to get the celestial pearl danio is its ability to live in nano tanks and breed there. Nevertheless, the fish requires stable tank conditions and some experience from its owner, therefore it can’t be recommended for beginners.
Keeping in a tank
Tank decor
The celestial pearl danio is an incredibly timid fish that thrives in a well-planted aquarium with a dark substrate. A dense arrangement of plants and shelters is essential for this species, as it helps reduce their shyness and allows them to exhibit natural behaviors. Floating plants can also enhance their sense of security.
However, if the tank is densely covered with plants, observing the fish can be challenging. Therefore, it’s advisable to arrange the plants in a way that creates open spaces in the center of the tank to provide clear viewing areas.
While the celestial pearl danio is active and friendly, it is also quite fearful. It should not be kept with large or aggressive fish, but it does well with small, peaceful tank mates such as shrimp. This fish is particularly well-suited for small, densely planted aquariums where it can feel secure and exhibit its natural behavior.
Tank size
Danio margaritatus are small fish that do not require a large tank. For a small group of these fish, a tank of 10 gallons (38 liters) or larger is suitable.
Yes, celestial pearl danios are schooling fish and should be kept in groups to ensure their well-being. While the minimum recommended group size is six individuals, a larger group is ideal. To truly observe their social dynamics and vibrant display, aim for a group of 10 to 15 fish.
However, due to their small size, a school of 20 to 30 celestial pearl danios will create a more impressive and engaging display. For such a group, consider a tank with a minimum capacity of 40 to 50 gallons (151 to 189 liters). This size will provide ample swimming space and allow the fish to exhibit their natural behaviors effectively.
Water parameters
For optimal care of celestial pearl danios (Danio margaritatus), maintain the following water parameters:
- Temperature: 72-75°F (22-24°C). The fish can become stressed if the temperature rises above 79°F (26°C), and temperatures reaching 86°F (30°C) can be lethal.
- Hardness (dH): 5-20°
- pH: 6.5-7.5
Stable water conditions within these ranges are crucial for the health and well-being of celestial pearl danios. Avoid sudden fluctuations or extreme values, as these can cause significant stress and negatively impact the fish’s overall health.
While celestial pearl danios do not thrive in strong water flow, moderate filtration and aeration are beneficial. Generally, these fish are adaptable and not overly demanding, provided their tank conditions are well-maintained and fall within the recommended parameters.
Tank mates
Ember tetra, harlequin rasbora will be perfect tank mates for celestial pearl danio. The galaxy rasbora becomes less shy and fearful in the presence of species of the same size living in the surface and middle water layers. Other small Cyprinidae species from Myanmar such as zebrafish or phoenix rasbora species are also good tank mates.
Due to the fact, that this is a schooling fish even juveniles male compete with each other almost all the time during the day light. The fish may sometimes eat shrimps juveniles, but they don’t eat adult shrimps and they are even afraid of them at times.
While they generally get along well with other peaceful community fish, there are some tank mates that may not be suitable due to differences in size, temperament, or water parameter requirements. Considering the galaxy rasbora shy temper it can’t be kept together with larger and active fishes, that may intimidate them or even take their food and leave them hungry. Surely, it’s impossible to keep them with the fishes that will take celestial pearl danio as food.
Here are a few examples of potentially inappropriate tank mates for Celestial Pearl Danios:
- Large predatory fish: Examples include larger cichlids like Oscars, predatory catfish species like Redtail Catfish, or aggressive species. These fish may see the smaller Celestial Pearl Danios as prey or exhibit aggressive behavior towards them.
- Fin-nipping species: Certain fish species, such as Tiger Barbs, Serpae Tetras, or Red Eye Tetras, are known to nip at the fins of other fish. Celestial Pearl Danios, with their delicate fins, may be susceptible to fin nipping and stress from these types of tank mates.
- Slow-moving or long-finned fish: Slow-moving fish like Fancy Goldfish or long-finned varieties of Betta fish (such as Halfmoon or Crowntail) may not be suitable tank mates for Celestial Pearl Danios. The active nature of the danios may cause stress to these slower or more delicate fish.
Diet
In their natural habitat, celestial pearl danios (Danio margaritatus) feed on small invertebrates, algae, zooplankton, and tiny worms. In an aquarium setting, they readily accept small-sized dry foods, but a varied diet is essential for their well-being. Given that these fish rarely swim to the surface, floating foods are not ideal.
To keep celestial pearl danios healthy and vibrant, offer a mix of live and frozen foods daily. High-quality options include cyclops, brine shrimp, and small tubifex worms. This diverse diet not only enhances their coloration but also encourages natural spawning behaviors.
For dry foods, choose high-quality flakes or pellets designed for small tropical fish. Ensure these foods provide a balanced diet with a variety of ingredients. Feed the fish small portions multiple times a day to replicate their natural feeding habits and avoid overfeeding. This approach helps maintain good water quality and supports overall fish health.
Gender differences: male vs female
Distinguishing between male and female celestial pearl danios (Danio margaritatus) can be subtle, particularly outside of breeding conditions. However, a few characteristics can help in identifying the sex of these fish:
- Size and Body Shape: Males are generally smaller and slimmer than females. Females, especially when mature and ready to spawn, tend to have a rounder and more robust body shape.
- Coloration: During breeding periods, males usually display more vibrant and intense colors, including brighter red or orange hues. Females often have a more subdued coloration.
- Fins: The dorsal fin of male celestial pearl danios is typically more elongated and pointed, while females tend to have a shorter and rounder dorsal fin. This distinction may not always be obvious.
- Behavior: In breeding conditions, males may exhibit more territorial behavior and engage in intense courtship and chasing of females. However, this behavior can vary and may not always be evident.
These differences can be subtle and may not be consistently noticeable in all individuals. Observing their behavior during breeding is often the most reliable way to determine their sex.
Breeding
Galaxy rasbora becomes reproductive at the age of 3 months, however it’s better to put them into a spawning tank not earlier then in 6 months after the fish was born.
Spawning usually occurs in the middle of small leaved plants and it doesn’t matter where they are located. It can happen both near the tank bottom or near the water surface in the floating plants.
Celestial pearl danio breeding is not difficult. In tanks the fish lays eggs somewhere on the tank plants such as Java moss (Taxiphyllum barbieri) or on some artificial surfaces.
Reproductive females have rounded abdomens and pronounced dark spots on them. When selecting a fish for spawning you can use this feature as an indicator that the galaxy rasbora is ready for spawning. The male selects a place for spawning and strikes a pose 2-3 cm far from the selected area. The fish stays motionless with its head down, body a bit curved, expanded and trembling fins.
It waits for a female to come. Once the female appears, a minute later the couple starts going to the spawning substrate. If other males notice this, they start doing the same. The celestial pearl danio female can lay up to 30 eggs in a time. The eggs incubate from 3 to 4 days at temperature 24-25 °C and they need 4 days more for larvae to start to swim.
During the first three days after hatching the larvae is dark colored and it stays on a solid surface. At this stage it is very hard to see between the larvae and detritus in a tank. Starting from the 4th day the larvae becomes lighter colored and starts to swim; it should be fed with encapsulated brine shrimp.
The galaxy rasbora is not demanding, but it grows very slow. At the age of 7-8 weeks the juvenile’s body starts to look like that of an adult. The juveniles are 1-1.2 cm long at the age of 1.5 months and at 3 months they are of the same size as the adult.
Their coloring starts forming a bit earlier, when they are 2 months old.