Cyprinidae, Subfamily Danioninae Common Names:
Celestial Pearl Danio, Galaxy Rasbora Origin and Habitat:
Originally thought restricted to one locality near Hopong in eastern Myanmar, it was subsequently discovered in other watercourses in the region and has been reported reaching into northern Thailand. Occurs in boggy areas and shallow ponds. Compatibility/Temperament:
Shy and quiet by nature, and given its minute size, it should have its own aquarium. Dominant males can be quite feisty, even nipping fins of rival males, but kept in a group of 20 or more lessens the damage. The tank should be well planted to break up the line of sight. Celestial Pearl Danio Diet
Very small foods that will sink, as the fish will not feed from the surface. Frozen daphnia and rotifers, live artemia (brine shrimp) are ideal; prepared foods may be taken but are not sufficient on their own. Size
Less than .75 inches; the largest specimen officially recorded was just 21mm (just over 3/4 of an inch). Minimum Tank Suggestion
18 inches in length [see explanation above] Water parameters for Celestial Pearl Danio
Soft (hardness below 5 dGH) slightly basic (pH 6.5-7.5) water, temperature 20-26C/68-79F. The water in its habit is slightly basic (alkaline) with a pH of 7.3 but is very soft. Description
This remarkably-coloured little fish was discovered in 2006 and many people were skeptical of the photographs; but once confirmed, it became one of the most sought-after fish in the history of the hobby. Exportation was banned by the Myanmar government who feared the species was near-extinction due to the thousands of fish being caught daily; it was subsequently discovered in other areas, and has further shown itself to be an easy fish to spawn in the aquarium.
Males are much more brightly coloured as can be seen in the first three photos below; the last photo shows a female. Like many of the small cyprinids, this one is an egg-scatterer and shows no parental care; in a thickly-planted species aquarium, spawning will likely be frequent and some fry should survive even with no intervention from the aquarist.
A dark substrate will cause the fish to display its deepest colouration which is certainly beautiful, and the aquarium should be thickly planted for the reasons noted above under Compatibility/Temperament. The fish spends its day in the lower half of the aquarium, and will not rise to the surface even to feed, so foods must be sinking as noted below. It is rather stationary, its only movement often the display of the males. Shy by nature, it may remain hidden if the plants are not thick.
Upon discovery in 2006, the species was generally seen under the name Microrasbora sp.
"Galaxy" or the Galaxy Rasbora. Upon being described by Tyson Roberts (2007) it was placed in the newly erected genus Celestichthys
in the Subfamily Danioninae, under the species name of margaritatus
; Roberts recognized its close similarity to Microrasbora erythromicron
but kept it separate. Disagreement from several ichthyologists followed, until Conway et al. (2008) concluded that the species is closest to Danio erythromicron
[originally described as Microrasbora erythromicron
but also moved to Danio
in 2008] and on the basis of a number of scientific traits assigned it to this genus.
The genus name Danio
is a vernacular name from India and Sri Lanka. The species epithet margaritatus
derives from the Latin and means "adorned with pearls" [source: Fishbase].
In a 2007 published study, Richard L. Mayden et.al. determined that the species then in Microrasbora
are in fact phylogenetically closer to Danio
, and subsequently all but one of the species were moved to other genera; Microrasbora rubescens
and M. microphthalma
are the two and only (to date) confirmed species in the genus. It is likely that these beautiful fish may appear under any of these names for some time. References:
Conway, Kevin, Wei-Jen Chen and Richard Mayden (2008), "The 'Celestial Pearl danio' is a minature Danio
(s.s.) (Ostariophysi: Cyprinidae): evidence from morphology and molecules," Zootaxa
No. 1686, pp. 1-28.
Mayden, Robert L., K.L. Tang, K.W. Conway, J. Freyhof, S. Chamberlain, M. Haskins, L. Schneider, M. Sudkamp, R.M. Wood, M. Agnew, A. Bufalino, Z. Sulaiman, M. Miya, K. Saitoh, S. He, (2007), "Phylogenetic relationships of Danio
within the order Cypriniformes: a framework for comparative and evolutionary studies of a model species," Journal of Experimental Zoology, Molecular Development and Evolution
308B, pp. 642–654.
Roberts, Tyson R. (2007), "The 'Celestial Pearl Danio,' a new genus and species of colourful minute cyprinid fish from Myanmar (Pisces: Cypriniformes). The Raffles Bulletin of Zoology
volume 55 (no. 1), pp. 131-140. Contributing Members
The following members have contributed to this profile: Byron