If you’re into nano community fish you may have already heard of the Celestial Pearl Danio. This Southeast Asian native is taking the hobby by storm and well worth a look if you’re considering adding a few to your collection!
What are Celestial Pearl Danios?
Celestial Pearl Danios are one of the hottest commodities in today’s fish hobby. They are also known as CPDs for shortened Internet parlance or Galaxy Rasboras. CPDs were discovered back in 2006 in the more mountainous regions of Myanmar.
Native to slow flowing to still weed-choked waterways, Celestial Pearl Danios experience significant seasonal variations in temperatures. This makes them fairly cold hardy despite living at a tropical latitude.
In aquaria they easily catch the attention of viewers despite being an inch long at maturity. And like their Danio and Rasbora cousins, CPDs are extremely easy to breed so long as you’re aware of their preferences!
- Scientific Name: Danio margaritatus
- Origin: Myanmar
- Length: 1 inch
- Aquarium Size: 5+ gallons
- Lifespan: 3 to 5 years
- Ease of Care: Easy
- Temperament: Peaceful; Shy
Celestial Pearl Danio Care
Here are some factors you should consider when caring for Celestial Pearl Danios:
Since Celestial Pearl Danios are nano fish that rarely grow beyond 1 inch they can be kept in the smallest of aquariums. You only need 5 gallons for a group of 6, which would be the bare minimum.
5 gallon planted nano tanks are some of my favorite designs. However I really enjoy having a diverse selection of fish, so I recommend keeping them in at least 10 gallons of space. That way you can have Tetras, Livebearers, and other fish to provide them with stimulation.
I always recommend people choose the largest tank they can afford unless they’re going for a specific concept. Large aquariums are more stable in terms of temperature and water chemistry. A small change will have a much greater impact on a small volume of water compared to a large one.
Also you’ll need to give them some breathing room if you’re keeping multiple males. CPDs compete aggressively for females and a subordinate male can be severely stressed if the dominant male manages to claim the entirety of a 5 gallon tank.
Celestial Pearl Danios prefer very moderate water chemistry. Slightly acidic to slightly basic is best (pH 6.5-7.5) with soft to mildly hard water is best. The closer you can get things to neutral (pH 7.0) the better. Many aquarists keep them in planted setups using reverse osmosis or distilled water.
Temperature-wise they are fairly hardy but prefer slightly cooler temperatures around 72-75F. Any warmer can be stressful and rarely results in successful breeding. As highland mountain fish CPDs are very cold tolerant and expect a bit of a chill now and again.
These conditions should be suitable for the vast majority of plants (see below) but you may find some soft water species harder to grow.
Current is also pretty irrelevant; in fact too much flow isn’t well liked. CPDs come from slow moving streams and still ponds. The water should be cool and well oxygenated but there’s no need for powerheads or strong filter outflow.
Plants and Decorations
This is where you’ll need to spend the most time considering your aquarium because Celestial Pearl Danios are rather shy fish. Many are wild-caught still so they are extremely skittish and easily stressed if kept in an open water layout.
CPDs prefer weedy, slow moving ponds and streams in the wild and you’ll want to replicate that habitat in your aquarium. The exact type of plants isn’t too important, however plants that provide shade work best.
I also recommend providing bushy plants for them to spawn in. Like most Cyprinids CPDs are egg scatterers. The male and female embrace among the weeds and the eggs are left to fend for themselves.
Easy to grow aquarium species include Hornwort, Java Fern, and Guppy Grass, which are excellent low light plants for beginners to try growing!
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Substrate isn’t too important so long as it can support plant life. I go into aquascaping substrates in much greater detail here. However I recommend ADA Aquasoil for the majority of setups with adequate lighting. It’s high in ammonia and plant nutrients (you’ll have to be careful of spikes when first adding it), attractive, and soil-based.
Tank Mates for Celestial Pearl Danios
Celestial Pearl Danios are model citizens in the majority of freshwater community tanks. Peaceful, shoaling, and only slightly scrappy towards each other, they typically ignore the other fish. Other nano fish are most likely to work.
Your main considerations for choosing tank mates should be:
- Low Temperature Tolerance
Best Tank Mates for Celestial Pearl Danios:
- Other small Cyprinids (Danios, Cherry Barbs, Rasboras, etc)
- Smaller Rainbowfish
- German Blue Rams
- Livebearers (Platies, Guppies, Endler’s Livebearer)
- White Cloud Minnows
- Pea Pufferfish
- Corydoras, Dwarf Otocinclus, and other small Catfish
Fish to avoid include anything that gets much larger than 4 inches. CPDs are small, slim, and an easy meal for even typically peaceful fish. Aggressive smaller fish should also be avoided.
Worst Tank Makes for Celestial Pearl Danios:
- Aggressive Gouramis (Bettas, Paradise Fish)
- Convicts and other aggressive smaller Cichlids
- Smaller predatory fish (African Butterflyfish, Leaf Fish, etc)
- Predatory Catfish (Pictus Catfish, etc)
Feeding Celestial Pearl Danios
Like most Cyprinids, Celestial Pearl Danios are omnivorous. This means they eat both plant and animal matter freely: soft leaved plants, plankton, tiny invertebrates, and fish fry are just a few of the items they regularly consume in nature.
In the home aquarium your best bet is to replicate their varied diet by providing fresh options like brine shrimp nauplii, bloodworms, and daphnia alongside appropriately sized pellets or flakes.
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A high quality spirulina flake provides a boost in vitamins and minerals that are missing from fish/shrimp meal and starch-loaded prepared formulas. In the case of Fluval-Hagen’s Vegetarian Fish Flake, they also provide kelp, garlic, spinach, and other terrestrial nutritious veggies for a complete nutrition profile!
How well they respond to prepared food depends mostly on their origin. Newly imported wild-caught CPDs will be much more reluctant to consider flakes and pellets. That’s why I always recommend keeping a quarantine tank on hand to prep new imports for the main aquarium.
If your fish are tank-bred they should already be trained on prepared foods. Remember it’s not bad manners to ask to see a pricier fish feed when considering a purchase from your local fish store. A poor feeding response could indicate internal parasites, stress, or other conditions you don’t want to deal with.
Breeding Celestial Pearl Danios
Interested in breeding Celestial Pearl Danios? This section is for you!
Sexing Males and Females
Fortunately for aquarists looking for the brightest colors male and female Celestial Pearl Danios are very similar in appearance. Once they reach their full adult size the differences are as obvious to us as they are to the fish.
Males have much more intense red/orange fins, a deeper shade of blue/purple to their flanks, and they spar with each other continually. The anal fin has a black stripe that’s used for signalling.
Females are typically less vividly colored and are noticeably chunkier in build. They also don’t spar with each other and sometimes move about in small groups.
Unlike most other Danios, CPDs aren’t exactly schooling fish. Rather, they form loose associations where the females move around in groups through the territory of males. Males will follow the females looking for mates while competing aggressively with each other for access to them.
Males are intensely competitive, as you’ll see in the below video:
If you want to keep multiples of the gorgeous males you’re better off with 10-20 gallons of space in a heavily planted tank. That way the loser of a bout has a safe place to retreat out of sight from the winner. Keeping two males in 5 gallons of space may result in a sick or dead male.
Conditioning them for Spawning
While still quite new to the hobby, Celestial Pearl Danios are as easy to breed as their cousins the Zebra Danio! The main requirements are clean cool water with a moderate chemistry, a rich, varied diet of tubifex worms and other high-calorie foods to fuel gamete creation, and thickly tangled plants for them to spawn in.
Many aquarists have good luck with fake spawning mats like mops and plastic Guppy Grass or Java Moss. CPDs reach sexual maturity in 3-4 months and will breed continuously throughout the year.
Once the male has secured a favored spawning location from his rivals he hovers there, displaying with his fins to passing females. If any are receptive they embrace over the plant mass in a complicated dance before releasing their eggs and sperm.
Afterward they go their separate ways. Like most egg scatterers Celestial Pearl Danios have no caregiving instinct and will even eat their eggs if they find them later.
Raising the Fry
CPD eggs are temperature-sensitive; 75-76F results in hatching in as little as 3 days while it can take up to 6 days if kept around 70F. Once they hatch the dark-colored fry are sedentary for their first 2-6 days (also temperature-dependent).
Once they begin moving about you’ll know it’s time to start providing infusoria, micro worms, and other tiny food offerings. Assuming you’re keeping them in a breeding tank you can also try weaning them onto powdered flake food as they grow.
Celestial Pearl Danios grow quite quickly and will be large enough to move back in with their parents in only a few months. And best of all there’s a huge market for these attractive Danios!