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Aqualife Beauty Uncategorized Galaxy Rasbora care: ultimate guide to healthy Celestial Pearl Danios

Galaxy Rasbora care: ultimate guide to healthy Celestial Pearl Danios

Galaxy Rasbora

You want to have the complete Galaxy Rasbora care guide on your finger tips? well, this article guarantees just that.

A little background though; Celestial Pearl Danios were “discovered” around 2006 is a freshwater, colorful, plump nano aquarium pet fish species whose popularity has grown steadily.

Does great in vegetation packed aquariums housing equally colorful and peaceful fishes just like it. A group of 6-7 keeps them beautifully active.

It’s very ideal for aquarium hobbyist beginners. Why you ask? Besides their small size, they’re so peaceable and with brilliant colors.

Also popularly known as Celestial Pearl Danio (with scientific name; Danio margaritatus but formerly Celestichthys margaritatus), they trace their origin to Myanmar in Asia. Its Danio family’s relation establishment resulted in the name change.

The rise in its popularity resulted in a huge decline in numbers, just within 2-3 years of its discovery. Luckily however, successful breeding in captivity around the same time helped to steady their numbers.  

Galaxy Rasbora; appearance and identification:

Celestial Pearl Danio is easily identifiable. Well, if you know what to look out for. Firstly, it has pearly spotting making it as colorful as the starry galaxy. Additionally, its tiny bodied, that even the mature one is less than 2 inches. That must be quite small.

The adult look of pearl-like spotting is a culmination of the gradual morphing of the stripped pattern donned at the juvenile stage. While human babies are gorgeous, funnily, juvenile celestial Pearl Danios are not compared to when matured.

Gill covers are transparent in both sexes. As a result, the beautiful gills’ red coloration magnificently shines through. Additionally, they have apparently more prominent, deep red/orange colored fins compared to their tiny bodies.

Further, because Galaxy Rasboras have sexual dimorphism (meaning that the two sexes are distinctively dissimilar in appearance), knowing their distinguishing features is important:

Male Galaxy Rasbora:

  • Have a slender and small size body profile,
  • A pair of black parallel lines separated by a bright scarlet/transparent area is visible in each set of fins except the pectoral fin,
  • Has a higher caudal peduncle (the narrow body section a fish right before the caudal fin),
  • Easily noticed by brightly colored fins with a still-to-deep blue body coloration background,
  • Easy to note bronze-green coloration especially on the back and the body spotting shimmering, tiny pearly white sprinklings,
  • Over spawning period, conspicuousness of the pearly dots increase as a result of darkening and brightening of flanks as well as reddening underbelly.

Female Galaxy Rasbora:

  • Has a plump body profile,
  • Compared to male counterparts, their caudal peduncle is lower,
  • Have a dull body base coloration which is more of blue-green,
  • Pattern less ventrals and fins with red-orange patches,
  • While may occasionally be on anal fin, the parallel black lines with a transparent area between them are predominantly in caudal and dorsal fins,
  • During spawning period, unlike the numerous changes in males, vent/anal black spotting is mainly the only notable change.

Celestial Pearl Danio care;

Galaxy Rasbora care management is not too demanding. Firstly, their tiny size eliminates the need for too big a tank. Just answer the following queries and you have happy and healthy Celestial Pearl Danios:

What is the right Celestial Pearl Danio’s aquarium size?

Purely on account of their size, they are comfortable nano tank pet fish. To hold up to 10 of them, a 10 gallon tank is sufficiently adequate. However, more space is needed should you need to vary the species in the tank.

Just to make it simple for you, the rule is, “a gallon for each inch of fish.”

How to set-up a Galaxy Rasboras’ tank;

You’ll inadvertently expose this pet fish to severe stress by holding it in an aquarium differently conditioned from its wild’s habitation. Stress, contributes to compromising the immunity of the fish. Subsequently, this makes it prone to diseases and infections.

Replicating their natural habitation therefore requires that the aquarium be densely covered with vegetation. As such, live plants must be part of the tank’s live matter. This allows the intensely shy Celestial Pearl Danios have hiding places.

Rocks and driftwood are great tank additions. They offer natural like hiding places as well as exploratory swimming areas.

Considering that they are mid-to-bottom swimmers, you’ll need substrate/sand/gravel at the bottom. While it will not dig on it, it’s a good place for it to hog on. On it too, grows algae they don’t mind nibbling on just like other tank plants. Importantly however, ensure that the sand is versatile enough for easy cleaning and good for the aquarium plants.

The right aquarium water parameters for Galaxy Rasbora:

Aquarium’s water quality has a direct effect on the lifespan of all pet fish in captivity. Disease causing toxins thrive in poor water quality. Besides, it causes the fish stress. As such, proper galaxy rasbora care must ensure consistent water quality.

How to maintain water quality?
  • Avoid overfeeding. Reduces chances of excess feeds and waste in the water decaying in the tank. Decay leads to the toxic ammonia and nitrite spike in the tank.  They MUST be at NIL level always.
  • Do regular water changes. However, the recommended maximum of tank water change is 20%-25%. NOT 100% in one change.
  • Effective and sufficient water filtration to remove pollutants; waste and food residue avoids decay in the tank.

Further, ensure that the temperature is right for safe habitation. For any fish, out of range tank temperatures affects appetite. For the galaxy Rasbora, the ideal temperature range is 69°F – 80°F. However, if you are keeping it with other tropical fish species, you can lower the temperatures a little further.

Additionally, you must also ensure the water’s pH and general hardness are within safe limits.

 Safe limits
pH Level6.5 – 7.5
Hardness level1 – 5 dGH

What do Celestial Pearl Danio eat?

Galaxy rasbora care extends to proper feeding. Just like goldfish (check article on “what do goldfish feed on?”), Galaxy Rasboras are omnivores. They are not overly picky. Therefore, whether in a community tank or in their wild habitation, they’ll eat anything they can fit in their mouth. This makes then easy to care for because of the vast variety of what you can feed them on.

Food in natural wild habitation;

Firstly, Danio margaritatus’ wild habitation is characterized by grass/wetlands that are naturally permanently-flooded. It is however shallow clear water flooding, averaging a 30cm – 50cm depth. As a result, aquatic plants and other lives thrive in these wetlands.

Therefore, out there in the wild, plants, zooplanktons, and algae are largely main source of food. Meanwhile, for their protein source, small vertebrae, crustaceans, larvae of small insects; these are easily available in the waters.

Food in the aquarium;

To ensure it has a healthy stay in the tank, you must provide a balanced, wholesome and healthy diet. Luckily, much of this is available in the form of micro-pellets and flakes, readily available in the pet stores near you.

Both live and frozen daphnia, brine shrimp, artemia, krill among others are great sources of proteins for the galaxy Rasboras. Actually, if possible, its encouraged to have an adult shrimp in the aquarium. It serves as a good supply of juvenile shrimps for food.

Besides increasing glow of its coloration, sufficient protein also hastens and encourages breeding.

Further, live foods are preferred over dried and frozen foods when a Danio margaritatus is placed in a new tank. While new tank imports come frail and weak, live feeds help in building strength quickly. In the meantime also, they also quicken the galaxy Rasboras’ settlement and acclimatization in the tank.

One attribute of Celestial Pearl Danios is that they are bottom to mid-tank level swimmers. As such, as part of your feeding pre-consideration, ensure to feed them on what they’ll comfortably reach. On surface floating foods are un-ideal.

Their mouths as well as digestive tract are tiny, matching their tiny body size. As a result, to safely feed, they need equally tiny food pellets.  


While they are generally not known to be aggressive, there sure are some peculiarities in personality. Subsequently, levels of shyness will differ among tank-mates.

Resultantly, some may feed more aggressively than others. To sort this, pick 2 feeding corners of the tank; one for the overly aggressive and the other for the slow and shy.

How do Galaxy Rasboras breed?

The first “aquarium breeding” was done in 2007. It was a great breakthrough because it alleviated the severe threat of their population reduction. 

It takes 6 – 12 months to adulthood and breed. In-fact, spawning can be so frequent in a mature and well/densely planted tank intervention-less; just the right tank conditions.

May sound reckless, but Danio margaritatus shows no parental care after eggs scattering.

Danio margaritatus Eggs and spawning:

Whether in the wild or in the aquariums, spawning is so often; almost daily, it seems. More often than not, a dozen eggs at most are expected in a single spawning. However, with 7 – 10 days of fish conditioning and sexes separation, occasionally, some females have had upto 30 eggs with a single spawning.

Because of egg predation which is prevalent mostly with egg scatters, separation of adults from eggs via spawning grate is advised.  Acrylic yarn spawning mops sets up plastic needle point canvas for a great spawning grate. Any slight disturbance of the mop or the plant will make the lightly adhesive clear eggs to easily sink to the bottom. 

How to increase fry yield:

While spawning can be so often without intervention, increasing the fry’s yield needs a little more controlled environment.  How?

  • With water from a mature tank, set-up a smaller sized tank (say at-least 15lt tank),
  • Using plant with fine leaves, for instance taxiphyllum or wool mops, fill-up the tank,
  • While you may not need filtration nor lighting, a sponge filter (an air powered)  isn’t advised against though,
  • Introduce a pair of Celestial Pearl Danios in the tank. Crowding the breeding tank may not be effective. That’s because egg predation may occur. Also, if more males are in the tank, fighting for dominance will distract them.
  • So that females have recovery time and reduce chances of predation, return the adults to the main tank,
  • The eggs hatch in about 72 – 120 hours (with temperatures of 76°F and 70°F respectively). Thereafter, in 3-5 days, the fry will be free swimming.
  • To increase survival rate of the fry, paramecium and commercial liquid fry foods are ideal food starters. Newly hatched brine shrimp can them follow.

What is the lifespan of Danio margaritatus?

With perfect galaxy rasbora care in a stable aquarium, it has a life span of about 3 – 5 years of sheer bliss, adding ultimate indoor aesthetics.

While it is timid, it however has very lively activity besides the pop of color it brings along.

It’s very ideal to keeping it in a community tank with other fishes of relatively similar size and mannerisms. This works to reduce chances of it being preyed on particularly by bigger fishes.   This, amongst the other care practices lengthens its lifespan.

Celestial Pearl Danio tank mates;

If you keep them in a community tank, observing size and behavioral similarity for compatibility with tank mates is paramount. It’s even better, if you keep same species for behavioral patterns uniformity.

For compatibilities, upper tank swimmer fishes like Neon Tetras are a good fit because galaxy Rasboras is mid-to-bottom tank swimmer. As such, they’ll peacefully co-exist in the tank.

Uniformity in behavior recommends co-existence with Guppies, Mollies, Killifish among a few others.

Keeping Celestial Pearl Danio in the wrong company only works to increase its shyness. It’s even worse if you miss-match with bigger and aggressive fishes. Besides the likely intimidation, they’ll also not be able to “compete” for food.

The table below gives a summary of the possible tank mates and their compatibility:

Perfectly compatiblePartially compatibleNon-compatible
Mollies, Swordtails, Tetra, Corydoras, Guppies, Minnows, Platies, Siamese fighter (both sexes), Angelfish, Dwarf Cichlids,   Loaches, Rainbow fish, DiscusShrimps, Giant Gourami, EelsFancy goldfish, Lobsters, Stingray, African and South American Cichlids, Knife fish, Crabs

Galaxy Rasbora common diseases;

Celestial Pearl Danio is a moderately strong fish. However, its immune system may be compromised if exposed to an unhealthy environment and stress. As such, maintaining the right water quality is paramount in preventing its immunity’s collapse.

Like with most other fresh water tanked fishes, of the many possible diseases, Ich and both fin and tail rot are commonest. Also prevalent are body fungus and swim-bladder.

However, unlike Ich and fin rot that are both bacterial, body infections can be both fungal and/or bacterial. These infections mostly afflict weak males bullied and injured in dominance establishment fights.

Ich (Also known as White spot disease):

It’s caused by the protozoan parasite. The parasite is highly prevalent in most tropical tanks. It’s largely ineffective in a stable tank. However, if for any reason the immunity of the fish is compromised, say by poor water quality, stress or by any other fish ailment/infection, then, the parasite effects afflict the fish.

Diagnosis of white spot disease:

The first and easily indicative sign is white spots rash on gills, fins and entire body literally. Additionally, you’ll notice body brushing and rubbing against hard tank surfaces and objects. Besides, lethargy is evident.

Treatment of white spot disease:

Besides improving water quality, just raising the tank’s temperatures to about 82oF. This however should be done gradually; 2-3oF per day for about 4 – 5 days. In similar manner, lower it gradually to the normal range. Additionally, you can add both white spot treatment and aquarium salts. Salts add electrolytes that increase response to treatment.

Fin Rot disease:

If not adequately treated, fin rot can result in death of the fish. Either of Aeromonas, Vibrio or Pseudomonas bacteria causes fin rot.

Diagnosis of Fin Rot disease:

Identified by fin discoloration and fading at the edges in its early stages. Continued spread of the disease causes inflammation with affected tissue bloodying and reddening. Patches of the fin also die and break off.

Treatment(s) for fin rot disease:

Luckily, it’s easily treatable. From your pet store, get proprietary commercial medication. Besides, work to improve the quality of water. With addition of aquarium salts, recovery is quick.

How to prevent/treat diseases and infections:

  • Always ensure the water stability is maintained. All the optimal safe and healthy tank parameters must be maintained always.
  • Proper feeding (especially quantities) and with the correct feeds should be ensured. In the time of illness or injury, medicated pellets can be used for treatment.
  • To avoid unnecessary injuries and likely potential injury infections, stock one or two males to avoid dominance fights and injuries.
  • For treatment, administer the correct antibiotics. Those that preferably contain malachite blue are most ideal. However, aquarium salts that induce response to medication as well as hastening recovery are advised.

What environmental disruptions affect the galaxy Rasbora?

While the tank water quality and other optimal parameters are observed, other happenings in or around the tank could cause your pet fish stress.  As stated earlier, stress has the effect of compromising immunity. As such, make it possible to eliminate or reduce to minimal possible levels of stress causing factors.

These could include but not limited to;

  • Excessive and unnecessary noises/vibrations: Remember, Danio margaritatus are very shy and peaceable pet fishes. Additionally, they are more of bottom tank swimmers. Subsequently, their acute sensitivity picks these external factors, making them be stressed out.
  • Smells and odors: These pollutants have irritation effect and subsequent stress arousal.
  • Improper lighting: Insufficient or excess light also has stress causing potential. Owing to the fact that they like thick tank plantation for hiding, light imbalance could either increase or limit their vibrancy.


Galaxy Rasbora is an easy pet fish to keep and care for. I hope this piece comes in

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