rasbora galaxy

12 December 2008 Modern Aquarium - Greater City A.S (NY)Modern Aquarium - Greater City A.S. (NY) December 2008 5

Celestichthys margaritatus - male Celestichthys margaritatus - female

A New Star in the GalaxyThe Celestial Pearl Danio, Celestichthys margaritatus

by ALEXANDER A PRIEST

The celestial pearl danio is a fairly newspecies, discovered in August of 1996.Originally, it was given a tentative scientific

name of “Microrasbora sp. 'Galaxy'” and acommon name of “galaxy rasbora.” (It wasinitially considered to be a member of theMicrorasbora genus, due to its similarity toMicrorasbora erythromicron.) It has now beenofficially described by taxonomist Tyson R.Roberts at the Smithsonian Tropical Researchinstitute in the Raffles Bulletin of Zoology inFebruary 2007, and placed in a new genus. It isnow known as Celestichthys margaritatus (whichmeans “heavenly fish adorned with pearls”) and ispresently the only species in the genusCelestichthys. It belongs to the subfamilyDanionae and to the family Cyprinidae. The firstarticle in a commercial magazine on this fish wasin the December 2006 issue of the Britishpublication, Practical Fishkeeping in its“Interesting Imports” column 1.

When the celestial pearl danio was firstintroduced to the hobby (as the “galaxy rasbora”),its exact collection location was kept secret forcommercial reasons. That location was eventuallydiscovered to be shallow wetland ponds in theSalween Basin, northeast of Inle Lake in Myanmar(formerly Burma). The bright colors and smallsize of this species made it an instant hit withhobbyists. It immediately became so popular thatonly two months after its introductory article onthem, Practical Fishkeeping reported that catcheswere down to just a few dozen per day, apparentlydue to over-collection2.

As a result, in February 2007, the governmentof Myanmar banned exports of the fish. Since

then, additional populations have been discoveredaround Hopong, a town in the Shan State of easternMyanmar3. Fortunately, this fish has also beenfound to breed in the home aquarium (it was firstbred in captivity in England by Pete Liptrot andPaul Dixon of the Bolton Museum Aquarium); anddomestically bred stock is usually available,although demand generally remains high.

The celestial pearl danio is a very small fishthat only attains a length of about one inch.Nonetheless, before its introduction to theaquarium hobby trade, these fish were caught,dried, and sold for food by the local people. A canof approximately 500 C. margaritatus, when soldas food, brought in about 25 kyat (or about $3.90U.S. dollars). Now, when sold to the aquariumtrade, each fish live is worth about one kyat. Thismeans that 500 live fish can bring in nearly $80 —a significant increase, especially for residents in acountry that remains one of the poorest nations insoutheastern Asia.

One of my all-time favorite fish is the pearlgourami, Trichogaster leerii. To a great extent, thecelestial pearl danio reminds me of the pearlgourami. It is one pretty little fish. Its body issprinkled with small, pearly dots, calling to mind(for me at least) the pearl gourami. (Interestingly,the chest of males is more orange, anothersimilarity to the pearl gourami.) The gill covers ofthe celestial pearl danio are transparent, allowingthe blood-red gills beneath to be clearly visible.The background body color of males is bright blue,with males being more brightly colored thanfemales, and having more red on their fins. Thecaudal peduncle is higher in males than in females.The red fins have black bars and patterns, which

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Modern Aquarium - Greater City A.S (NY) December 2008 136 December 2008 Modern Aquarium - Greater City A.S. (NY)

Scientific name: Celestichthys margaritatusCommon name: Galaxy Rasbora,

Celestial pearl danio, Fireworks RasboraGeographic location: Myanmar (Burma)Size: Up to 1 inch (2.5cm)Temperament: PeacefulTemperature: 70EF-78EFAcidity: pH 6.8-7.5 Hardness: Slightly hard to slightly softSkill level: IntermediateMinimum tank size: 2.5-5 gallonsReproduction: Egg scattererNutrition: Omnivorous

Map of Myanmar with Lake Inle circled

are more numerousand darker inmales. In general,females are lesscolorful and haverounder bodies.While a generallypeaceful species,males will flare outt h e i r f i n s“squaring” to eachother, resulting insome spectaculardisplays (when youare lucky enough tocatch them at it, asthis is also a very shy species).

These fish are egg scatterers. I have read andbeen told that their tank should have marbles, orJava Moss, or a screen toallow eggs to fall into andto prevent the adults fromeating the eggs. I havealso read and been toldthat the fry need livemicro organisms to feedon for the first few daysof their lives. Well, I hada group of a half-dozencelestial pearl danios in afive-gallon tank, with noJava Moss, no marbles (infact no substrate at all),but with two caves (onemade from a coconut shellwith an Anubias sp.c o f f e e f o l i a p l a n tattached). One day, mywife told me that she sawfry in the tank. Sureenough, with only flakef o o d ( t h e y a r eomnivorous, and will eatflake, pellet, freeze-dried,live, or frozen food, if it issmall enough), and veryminimal maintenance, my celestial pearl daniosspawned, and some fry survived. (It should benoted that this tank had both a box and a spongefilter, and that it is quite possible that naturallyoccurring microorganisms on the sponge filterwere sufficient to feed the newly hatched fry.)

Some collectors claimed that the water inwhich these fish are collected has a pH of 7.3(slightly alkaline) with a hardness of 7 GH(slightly hard). My New York City tap water isvery soft, and has a neutral pH (7.0, almostexactly). The coconut shell in their tank appears toleach tannins into the water (making it somewhat

tea colored) so thatthe actual pH my fishspawned in wasslightly acidic (6.8 orso). In their nativehabitat, the watertemperature is around70EF, but since thewater is shallow, it isalso prone to rapidt e m p e r a t u r efluctuations.

So, you can seethat this is basically arelatively tough andadaptable little fish.

It should do well in a fairly wide range of waterconditions, and is suitable for almost anycommunity tank of small, peaceful fish. It might

also be a good candidatefor a mini or desktopaquarium.

If you see them, theyare certainly worthchecking out, especiallyif you have a communitytank of very peaceful fish,or a spare small tankavailable. While they arenot all that common yet inpet stores, they do oftenpop up in Internet salesand auction sites (such asaquabid.com) or ina q u a r i u m s o c i e t yauctions. (In fact, I gotmy fish at a Greater CityA q u a r i u m S o c i e t yauction.)

References

1 Clarke, Matt: “The next big thing: Microrasborasp. Galaxy,” Practical Fishkeeping, September2006.

2 Clarke, Matt: “Galaxy rasbora under threat”Practical Fishkeeping February 2007.

3 Clarke, Matt: “New populations of Celestichthysdiscovered” Practical Fishkeeping, June 2007.



rasbora galaxy

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