About the Celestial Pearl Danio
Species Type: Freshwater Fish
Care Level: Easy. Does well in a slightly more narrow range of water parameters and shouldn't be used to cycle an aquarium. Will eat most prepared foods. May have some specific care requirements in terms of particular water parameters, social behaviors, food items etc.
Origin: 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.
This remarkably-coloured little fish was discovered in 2006 and many 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 and second photos; the third 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 will 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 Sub-Family Danioninae, under the species name of margaritatus; Roberts recognized its close similarity to Microrasbora erythromicron but kept it separate. Disagreement from several ichthyologists followed, and in 2008, Kevin Conway (with Wei-Jen and Richard Mayden) 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.
In a 2007 published study, Richard L. Mayden et.al. determined that the species then in Microrasbora are in fact phylogenetically closer to Danio than Rasbora, and subsequently all but one of the species were moved to other genera; Microrasbora rubescens is the sole confirmed species in the genus, although M. microphthalma and M. rubescens "Thuzari" are still uncertain. It is likely that these beautiful fish may appear under any of these names for some time.
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.
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]
Ideal 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.