Celestial Pearl Danio / Galaxy Rasbora (Danio margaritatus)

One of the most iconic nano fish for planted aquariums — featuring a deep blue-black body covered in pearl-like spots, vivid red-orange fins, and fascinating display behaviour in a properly established group.

The Celestial Pearl Danio, Danio margaritatus, is also widely known as the Galaxy Rasbora or simply CPD. Despite the long-established Galaxy Rasbora trade name, this species is actually a true danio rather than a rasbora.

Reaching only around 2–2.5 cm, CPDs are ideal for mature planted aquariums, aquascapes, and carefully planned nano communities. Their small size does not mean they should be kept in tiny groups or bare tanks: plant cover, appropriate food size, and strong group numbers make a major difference to confidence, colour, and natural behaviour.

Why This Fish Stands Out

• Iconic pearl-like spotting over a deep blue to blue-black body
• Adult males develop vivid red-orange and black fin markings
• Very small adult size of approximately 2–2.5 cm
• Excellent choice for mature planted and aquascaped tanks
• Peaceful toward other appropriately sized community fish
• Generally compatible with adult freshwater shrimp
• Interesting male display, sparring, and breeding behaviour
• One of the most recognizable nano fish in the freshwater aquarium hobby

Topick Aquarium Insight

The most common mistake with Celestial Pearl Danios is buying only a few and then wondering why they remain hidden.

CPDs are naturally social, but they are better described as a loose shoaling fish than a tight open-water schooling fish. Males regularly display and briefly spar with one another, especially when mature and in breeding condition.

In a small group, that attention can become concentrated on only a few fish. In a larger group with dense plants and broken sight lines, social pressure is distributed much more naturally and the fish usually become more confident.

For most aquariums, we recommend starting with at least 8–10 CPDs. Groups of 10–15 or more are even better when aquarium size allows.

This is why our 10-fish option is not simply a bulk pack — it is the group size we would normally prefer customers to start with when setting up a dedicated CPD display.

Celestial Pearl Danio, Galaxy Rasbora or CPD?

All three names refer to the same fish:

• Celestial Pearl Danio: the most widely accepted modern common name
• Galaxy Rasbora: the original aquarium trade name and still a very common search term
• CPD: the hobby abbreviation for Celestial Pearl Danio
• Scientific name: Danio margaritatus

The fish was initially introduced to the aquarium hobby as a Galaxy Rasbora before its taxonomic relationship with true danios became clear. The Galaxy Rasbora name remains extremely common, but it is not actually a member of the genus Rasbora.

Natural Habitat — Not a Blackwater Fish

Celestial Pearl Danios originate from shallow, clear, heavily vegetated wetland habitats associated with the Salween / Thanlwin drainage in Myanmar.

Their known natural habitat contains dense aquatic vegetation and very shallow water, which explains why CPDs respond so well to heavily planted aquariums.

One important misconception is that every tiny Southeast Asian fish needs very soft, acidic blackwater. CPDs are not a classic peat-swamp or blackwater species. Their known habitat is clear and vegetated, and water around neutral to slightly alkaline conditions has been recorded in their native range.

For aquarium keeping, stability matters more than trying to reproduce one exact wild pH number.

Tank Size & Aquarium Setup

A 10-gallon aquarium is a practical minimum for a small CPD group, but 15–20 gallons or larger provides better stability, more plant structure, and more room for a larger social group or carefully selected tank mates.

• 10 gallons minimum for a properly managed small group
• 15–20 gallons or larger preferred for a community or larger group
• Dense live planting strongly recommended
• Fine-leaved plants and moss provide excellent cover
• Floating plants can help create shaded areas
• Leave small open areas for feeding and male display
• Dark substrate can improve security and visual contrast
• Gentle to moderate filtration is ideal
• Avoid excessively turbulent flow
• A mature, biologically stable aquarium is strongly preferred

The best CPD aquarium is not completely packed with plants and it is not completely open. Dense planted areas combined with small open pockets allow timid fish to retreat while still giving males space to display.

Water Parameters

• Scientific Name: Danio margaritatus
• Common Names: Celestial Pearl Danio, Galaxy Rasbora, CPD
• Former Scientific Combination: Celestichthys margaritatus
• Origin: Shan State, Myanmar; Salween / Thanlwin drainage
• Adult Size: approximately 2–2.5 cm
• Temperature: approximately 20–26°C
• pH: approximately 6.5–7.5
• GH: approximately 5–15 dGH
• Recommended Group: at least 8–10; larger groups preferred
• Minimum Tank: approximately 10 gallons / 38–40 L
• Temperament: Peaceful; males display and spar
• Diet: Omnivore / micro-predator
• Care Level: Beginner to Intermediate

CPDs tolerate a reasonable range of aquarium conditions once established. A stable aquarium with consistent temperature and mineral content is much safer than repeatedly adjusting the water to chase one exact number.

Topick Aquarium Livestock Standard

Every Celestial Pearl Danio sold by Topick Aquarium goes through our livestock conditioning process before becoming available for sale.

We follow our One Tank. One System. approach to reduce unnecessary cross-system exposure and maintain better control over livestock condition.

Our fish are quarantined and conditioned to our stable local tap-water system before sale. This does not mean customers should ignore their own aquarium parameters — temperature and water chemistry should still be matched gradually during acclimation — but it means the fish are not being maintained in unstable or artificially manipulated conditions immediately before sale.

Natural Colour & Livestock Integrity

Adult male CPDs can become dramatically more colourful than newly arrived juveniles. Mature males develop a darker blue body, bright pearl-like spots, and intense red-orange fins with dark markings.

Colour develops through genetics, maturity, diet, health, social interaction, and suitable aquarium conditions.

Topick Aquarium does not use hormones or artificial colour-enhancing treatments to make fish appear more colourful for sale.

Recently transported fish can temporarily appear pale. A healthy CPD normally develops significantly better colour once settled, feeding confidently, and interacting with a proper group.

Male vs Female Celestial Pearl Danio

Mature males and females become reasonably easy to distinguish once properly conditioned.

• Males: generally slimmer, darker blue, and much more intensely coloured, with stronger red-orange fins and darker fin markings
• Females: generally rounder through the abdomen with more subdued body and fin coloration
• Juveniles: can be difficult to sex reliably before mature colour develops

Males may flare their fins, circle, and briefly chase one another. This is normal display behaviour when it remains short and does not result in one individual being continuously harassed.

Feeding

Celestial Pearl Danios have very small mouths and should be offered appropriately sized food.

• High-quality micro pellets
• Finely crushed quality flakes
• Frozen or live cyclops
• Baby brine shrimp
• Daphnia
• Microworms and other appropriately sized live foods

Small live and frozen foods are especially useful for newly settled fish and breeding groups.

Avoid combining CPDs with extremely fast, aggressive feeders unless you are able to ensure that enough food reaches the CPD group. Their small size and relatively cautious feeding behaviour can allow larger fish to outcompete them.

Tank Mates

CPDs are peaceful toward other species and are best combined with small, calm fish that enjoy similar temperatures.

Suitable choices can include:

• Other Celestial Pearl Danios
• Small peaceful rasboras
• Small peaceful tetras with compatible temperature requirements
• Pygmy Cory-type catfish
• Otocinclus
• Small peaceful loaches
• Amano Shrimp
• Adult Neocaridina and Caridina Shrimp
• Peaceful freshwater snails

Avoid large predators, highly aggressive fish, and very fast or boisterous species that continuously dominate feeding time.

Can Celestial Pearl Danios Live With Shrimp?

Yes. CPDs are one of the better fish choices for a planted aquarium containing adult freshwater shrimp.

Adult Neocaridina, Caridina, and Amano Shrimp are generally too large to be considered prey. However, newly hatched shrimplets are extremely small and may be eaten opportunistically.

If maximum shrimp reproduction is the goal, a shrimp-only aquarium is still the safest option. If the goal is a planted display aquarium containing both shrimp and small fish, CPDs are an excellent candidate.

Breeding Celestial Pearl Danios

CPDs are egg scatterers and can breed readily once mature fish are healthy and well conditioned.

Spawning normally occurs among moss, fine-leaved plants, or other dense structure near the bottom. Females deposit small batches of mildly adhesive eggs and the adults provide no parental care.

Adults may eat both eggs and fry. For higher breeding success, breeders can use dense moss or spawning mops and remove either the eggs, spawning media, or adult fish after spawning.

Eggs generally hatch in approximately three days depending on temperature. Newly free-swimming fry are extremely small and require microscopic first foods before they are large enough to accept baby brine shrimp.

Celestial Pearl Danio vs Emerald Dwarf Danio

Celestial Pearl Danio and Emerald Dwarf Danio (Danio erythromicron) are closely related but are different species.

• Celestial Pearl Danio: dark body covered in pale pearl-like spots with red-orange fin markings
• Emerald Dwarf Danio: body pattern dominated by vertical turquoise-blue bars

Because the two species are closely related and hybridization has been reported as a concern, we do not recommend mixing them in a breeding project where maintaining pure lines is important.

Is a Celestial Pearl Danio the Same as a Pearl Danio?

No. The Celestial Pearl Danio is Danio margaritatus. The much larger fish normally sold simply as the Pearl Danio is a different species, Danio albolineatus.

CPDs remain around 2–2.5 cm and prefer a structured planted environment, while standard Pearl Danios are substantially larger and much more active open-water swimmers.

Canada-Wide Live Fish Shipping

Celestial Pearl Danios are available from Topick Aquarium in Canada when in stock. Local pickup is available from our Markham / Unionville location.

Canada-wide live fish shipping is also available for suitable routes and weather conditions. Extreme temperatures or livestock considerations may affect the safest shipping schedule.

Learn more about Topick Aquarium's Canada-wide live fish shipping process.

Want to Learn More About CPD Care?

For a deeper look at why CPDs hide, how group size changes their behaviour, and how to build a better planted setup, read our complete species guide:

Celestial Pearl Danio / Galaxy Rasbora / CPD Care Guide

You can also explore more species in our Danios & Killifishes collection .

Important Note

Individual colour, sex, size, fin pattern, and maturity can vary. Juvenile fish are naturally less colourful than fully conditioned adult males.

Unless specifically listed as WYSIWYG, product photos should be considered representative of the species rather than an exact image of every fish sold.

Frequently Asked Questions

Is Celestial Pearl Danio the same as Galaxy Rasbora?
Yes. Celestial Pearl Danio, Galaxy Rasbora, and CPD all commonly refer to Danio margaritatus. Galaxy Rasbora is an older aquarium trade name.

Is Galaxy Rasbora actually a rasbora?
No. Despite the trade name, the accepted scientific name is Danio margaritatus, making it a danio rather than a true member of the genus Rasbora.

How many Celestial Pearl Danios should I keep?
We recommend at least 8–10, with groups of 10–15 or more preferred when aquarium size allows. Larger groups usually improve confidence and spread normal male competition across more individuals.

What tank size does a Celestial Pearl Danio need?
Approximately 10 gallons is a practical minimum for a small properly managed group. A 15–20 gallon or larger planted aquarium is preferable for larger groups or community setups.

Can Celestial Pearl Danios live in a 5 gallon tank?
We do not recommend a 5 gallon as a normal long-term CPD setup. Their social requirements, male display behaviour, and need for planted structure make a larger footprint much more suitable.

Why are my Celestial Pearl Danios hiding?
Small groups, bright open aquariums, insufficient plant cover, aggressive tank mates, and competition for food can all make CPDs excessively shy. Increasing group size and adding structured plant cover often improves confidence.

Do Celestial Pearl Danios need blackwater?
No. Their known natural habitat is shallow, clear and heavily vegetated rather than classic acidic blackwater. Stable water around neutral conditions works very well.

What temperature is best for CPDs?
Approximately 20–26°C is a suitable aquarium range. They generally do not need the very warm temperatures used for species such as Discus or German Blue Rams.

Do Celestial Pearl Danios need a heater in Canada?
It depends on room temperature. If the aquarium remains stable within their suitable temperature range, additional heating may not always be necessary. A heater is useful when room temperatures fall too low or fluctuate significantly.

Can Celestial Pearl Danios live in tap water?
Yes, when the tap water is within a reasonable range and the aquarium is stable. Topick Aquarium conditions CPDs in our stable local tap-water system before sale. Avoid sudden changes in temperature or mineral content during acclimation.

Can CPDs live with shrimp?
Adult Neocaridina, Caridina, and Amano Shrimp are generally compatible. Very small newborn shrimplets may still be eaten opportunistically.

Are Celestial Pearl Danios aggressive?
They are peaceful toward most tank mates. Mature males regularly display and briefly spar with one another, which is normal. Larger groups and dense planting help prevent one fish from receiving too much attention.

How can I tell male and female CPDs apart?
Mature males are normally slimmer with deeper blue coloration and stronger red-orange fins. Females are usually rounder through the abdomen and less intensely coloured.

Are Celestial Pearl Danios easy to breed?
Healthy mature CPDs often spawn readily among moss and fine plants. The main challenge is protecting eggs and very small fry because adults may eat them.

Is Celestial Pearl Danio the same as Emerald Dwarf Danio?
No. CPD is Danio margaritatus, while Emerald Dwarf Danio is Danio erythromicron. They are closely related but have distinctly different body patterns.

Is Celestial Pearl Danio the same as Pearl Danio?
No. Pearl Danio normally refers to Danio albolineatus, a much larger and more active species. Celestial Pearl Danio is the much smaller Danio margaritatus.