Celestial Pearl Danio
Danio margaritatus
Spotted nano fish from cool Burmese poolsIntermediate
- Lifespan
- 3-5 years
- Size
- 2-2.5 cm / 0.8-1 in
- Social needs
- Social; keep 6+ together
- Time
- Low-moderate; daily feeding, weekly water change
- Cost
- Low-Medium
- Diet
- Omnivore; micro pellets, crushed flakes, frozen foods
Overview
What is this animal?
- The celestial pearl danio, also sold as the galaxy rasbora, is a tiny fish described in 2006 from cool, weedy spring pools in Myanmar.
- Males show pearl spots over a deep blue body with orange-red fins, making it a popular nano species.
- Wild populations were quickly over-collected after discovery, so seek captive-bred stock, which is now widely available and hardier.
- It is not difficult to keep but is shy and small, needing a thoughtfully planted tank rather than a busy community.
Temperament
- Peaceful but shy, celestials are not a true tight shoal; males display and spar gently among themselves while staying close to cover.
- A larger group spreads out this sparring and encourages confident, colourful behaviour.
- They suit calm nano setups with other small, gentle species and shrimp, but are easily bullied or outcompeted by larger, faster fish.
- Keep them with equally peaceful tankmates so they feed and display without intimidation.
A good fit for
- Planted nano and biotope aquariums
- Cooler, unheated or low-heat setups
- Keepers seeking a captive-bred species
- Peaceful shrimp-friendly community tanks
Common mistakes to avoid
- Buying over-collected wild-caught stock
- Keeping them too warm or in strong flow
- Housing with larger, faster tankmates
- Sparse tanks leaving shy fish no cover
Enclosure
Minimum 40 litres (11 US gallons) — for a group of 6
Cannot be kept alone. The minimum is 6, and the space above is for that group.
- A group of six or more suits a planted 40-litre (10-gallon) nano, filtered and held at 20-24C; they prefer cooler water than most tropicals and often need no heater in a warm room.
- Dense planting, fine substrate and gentle flow recreate the still, vegetated pools they inhabit.
- They are timid and need plenty of cover to feel secure and display.
- Avoid strong current and overly warm water, and choose a well-cycled, stable tank, since such small fish are sensitive to swinging parameters in small volumes.
Supplies
Setup
- Tank and stand
- Filter
- Heater and thermometer
- Substrate, plants and decor
- Liquid test kit
- Dechlorinator and starter supplies
Ongoing
- Quality tropical flake or micro-pellet
- Frozen daphnia
- Frozen brine shrimp
- Frozen or freeze-dried bloodworm
- Spirulina or vegetable flake
- Small feeding spoon for measured pinches
- Fine net for removing leftovers
Safe substrate: Inert aquarium gravel · Fine, smooth sand · Aquasoil for planted tanks
Care routine
Daily
- Check temperature and equipment
- Feed
- Head-count and look everyone over
Weekly
- Top up evaporationevery 3 days
- Check the lid
- Clean glass and clear algae
- Test the water
- Water change and gravel vacuum
Monthly
- Trim and thin the plantsevery 2 weeks
- Check supplies and reagent dates
- Rinse the filter media
Less often
- Replace chemical filter media (Carbon/Purigen)every 2 months
Vet: Quarterly temperature and stocking review — every 3 months
Top resources for more info
Independent creators and organisations we would send a friend to. We have no affiliation with any of them, and nothing here is sponsored. Links checked 2026-09-19.
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Diet
- These are micro-predators that pick tiny invertebrates from plants and substrate.
- Offer fine micro-pellets, crushed flake and powdered foods as the base, supplemented generously with frozen or live cyclops, baby brine shrimp, daphnia and microworms.
- Feed small amounts once or twice daily, ensuring food is small enough for their minute mouths.
- Live and frozen foods bring out their best colour and breeding condition, so rotate them in regularly alongside the dry staple.
Health
- Captive-bred celestials are reasonably hardy, but wild-caught fish arrive stressed and prone to parasites and rapid decline.
- Ich and fin rot follow chilling or unstable water, and their tiny bodies show illness quickly.
- Buy captive-bred stock, acclimatise slowly and quarantine new arrivals.
- Keep water stable and on the cool side, perform weekly partial changes, and avoid crowding, as the small volumes of nano tanks punish overstocking and inconsistent maintenance.
Is your enclosure big enough?
Is this urgent?
In a fish tank the patient is usually the water. Test before you treat — dosing a healthy tank for a disease it does not have makes things worse.
Go now
Today
Soon
Never add a new fish to a tank that is not fully cycled, and never treat blind. A test kit is cheaper than the fish.
This is general guidance for a healthy adult, not a diagnosis. An exotics vet who knows your animal always overrides it — and the time to find one is before you need one.
What it really costs
Setup, monthly, first year and across a whole life, itemised and with the electricity worked out from the actual wattage. Published figures for the same animal disagree by a factor of four, so the calculator shows ranges rather than picking one.
Bedding and substrate
Substrate in an aquarium is a filter as much as a floor. Most of the biology lives in and on it.
Safe
With a caveat
Never
This is our general list for freshwater fish. We have not built one specific to Danios & Minnows yet.
My kit says 0.25 ppm. Is that dangerous?
A liquid kit measures total ammonia, but only the un-ionised fraction is really toxic, and that fraction is governed by pH and temperature — each whole pH unit multiplies it roughly tenfold. So the same reading can be nearly harmless in one tank and lethal in another; this works out which one you are in.
Compare with other animals
The same axes for every animal, side by side — the way the guides are written makes that a fair comparison rather than two articles.
Danios & Minnows, side by side
Same axes, same care guides — the honest way to choose between types.
See all Danios & Minnows side by side →
