Celestial Pearl Danio (CPD / Galaxy Rasbora)

Danio margaritatus

The Micro-Galaxy (Under 1 inch / 2 cm). Discovered in 2006, the Celestial Pearl Danio completely shocked the hobby with its unbelievably stunning, painting-like colors: a deep midnight-blue body dotted with golden stars, finished with blazing neon-red striped fins. Despite its extreme beauty, it is notoriously shy, cowardly, and delicate. It absolutely demands heavily planted tanks, dim lighting, and massive schools. If kept in a bare tank with loud, fast fish, it will lose all its color, hide constantly, and slowly fade away.

Family: Cyprinidae
Origin: Myanmar (Lago Inle)
Origin: South and Southeast Asia
Tank use: Used in 0 tanks

Species challenges

Temperature

20 °C - 25 °C

6.5 - 7.5

Water type

Freshwater

Tank level

Middle

Adult size

2 cm

Description

Geographic Origin and Biotope: Discovered in 2006 in Hopong (Myanmar), in very small permanent karst ponds and swamps at about 1,000 meters (3,300 ft) above sea level. Cool, shallow waters, invaded by dense meadows of Anacharis or water mosses.

Taxonomy and Morphology: Celestial Pearl Danio (CPD) / Galaxy Rasbora (Danio margaritatus). The fish that sent the global aquarium hobby into a frenzy. Barbel-less nano-fish, with an upturned mouth to hunt micro-fauna in the moss.

Social Behavior: Rather shy but fascinating, spends its time exploring the thicket. Gregarious: form colonies of at least 12-15. Males engage in constant and spectacular spiral displays for territory (sometimes tearing fin fragments).

Coloration and Sexual Dimorphism: Deep blue body sprinkled with pearlescent "galactic" spots. Fins (anal, pelvic, caudal) crossed by parallel bright red and black bands. Females are duller (gray-green background) and with a markedly rounder belly.

Care and observations

Aquarium Setup: Ideal for nano-aquariums (40-60 cm / 16-24 inches) devoted to Aquascaping, very rich in dense plants, carpets and mosses. Moderate light, weak water flow (no strong current) and strict respect for proportions.

Diet and Feeding: Micro-predator. Its mouth is tiny. Pulverized granules (0.3 - 0.5 mm) of the highest quality and brine shrimp nauplii, microworms and cyclops (often vital for reproduction or acclimatization of wild or weak specimens).

Water Quality: Very stable tank, nitrates at zero. Avoid temperatures stably above 25°C (77°F), under penalty of lethal metabolic acceleration (it is a mountain fish). Neutral-alkaline pH is tolerated without problems.

Compatibility and Tankmates: Species-only keeping is recommended. Excellent companions are small Caridina/Neocaridina and snails. Ideal companions, if a community is desired, are Boraras and Otocinclus. Not recommended with any large or ravenous fish.

Aquarium Reproduction: Continuous spawning if well fed. Females scatter 10-30 adhesive eggs per day in moss bushes. Separate the moss weekly into small tanks to obtain fry.

Risks and Diseases: Susceptible to fish tuberculosis (Mycobacterium) and progressive wasting (sunken belly) if purchased in malnourished stocks and kept at torrid temperatures.

Fish profile

Temperament: Timido e cauto. Tendono a nascondersi tra le piante se spaventati. Tuttavia, i maschi sono formidabili "sparring partner" che passano le giornate a danzare in circolo (sparring) sfoggiando le pinne rosse per stabilire gerarchie e dominare piccole aree di muschio.
Diet: Micro-Predatore. Questa è la loro vera difficoltà. Hanno bocche microscopiche e non masticano il cibo sbriciolato. Richiedono alimentazione mirata con micro-cibo vivo o congelato di alta qualità: naupli d'artemia (freschissimi), anguillule dell'aceto, moina, daphnia e microworms. Se nutriti solo con scaglie deperiranno.
Tank level: Middle
Minimum group: 10
Adult size: 2 cm
Minimum tank: 30 L
GH: 5 dGH - 15 dGH
KH: n/a
TDS: n/a
Conductivity: n/a
Sex ratio: Harem (1 maschio per 2 femmine). Un errore comune è avere troppi maschi in spazi ristretti; si danneggeranno gravemente le pinne a furia di combattere in modo incessante per i territori.
Feeding frequency: Piccole quantità 2-3 volte al giorno (essendo molto piccoli hanno metabolismi veloci e poco spazio nello stomaco).
Bioload: Bassissimo
Flow: Corrente da Nulla a Debole (odiano i flussi forti)
Jump risk: Covered tank required
Reproduction: Egg-scatterers continui. Una volta ambientati depongono fino a 30 piccole uova poco adesive al giorno tra i muschi (Java Moss). Non praticano vere cure parentali, ma se il muschio è abbastanza fitto e il branco è ben nutrito, non è raro veder spuntare miracolosamente dei minuscoli avannotti in vasca senza aver fatto nulla.
Compatibility: Da tenere in vasche monospecifiche o uniti SOLO a pesci di stazza altrettanto lillipuziana (Boraras, Danio erythromicron, Corydoras pygmaeus). Ottimi coinquilini per le caridine Neocaridina (cherry shrimp). Se messi con pesci normali (es. Barbus, grossi Tetra), passeranno la vita nascosti per la paura.

Image gallery

Licensed images linked to the species or, when marked, to the closest representative taxon.