Celestichthys margaritatus

A Little More Information...

The Galaxy Rasbora, also known as the Celestial Pearl Danio, is a tiny cyprinid native to Myanmar. Its dark body, covered with pearly spots and enhanced by red fins, explains its great popularity in the aquarium hobby. Despite its small size, Celestichthys margaritatus has an active personality and becomes especially interesting when kept in a group. It prefers a mature, densely planted aquarium with small, peaceful companions. Care is accessible, but its tiny mouth requires appropriately sized food. Relatively common in the specialty trade, it is still sensitive to water quality and to overly boisterous tank mates.

General description of the species

Celestichthys margaritatus is a small schooling fish in the family Danionidae, valued for its striking colors and discreet behavior. It usually occupies the lower and middle areas of the aquarium, moving in short bursts among the plants. A group of at least 8 to 12 individuals encourages natural behavior and allows males to display without placing excessive social pressure on a single female. Males regularly display to one another, while females are generally rounder and often less intensely colored. This is neither a bottom fish nor a fast open-water swimmer; it is better suited to a calm, shaded and well-structured aquarium with plenty of visual cover.

Geographic origin and habitat

Country of reference: Myanmar. The species comes from Shan State in the northeastern part of the country, around the Inle basin and the Hopong region. It is associated with small water bodies and drainage areas connected to the Nam Lang, rather than with large open rivers. These habitats are usually shallow, still or very slowly renewed, with clear water that may be lightly stained by organic matter. The natural environment combines subdued light, aquatic plants, submerged grasses and plant debris. In the aquarium, this origin translates into a preference for stable water, good oxygenation, gentle filtration and abundant vegetation that provides visual shelter.

Precise location and local name

The first known populations were found near Hopong in Shan State, eastern Myanmar, close to wetlands and small streams within the Inle basin. The scientific name quickly replaced the commercial names used when the fish entered the aquarium trade. The most common aquarium names are Galaxy Rasbora, Celestial Pearl Danio and Galaxy Rasbora; the English name Galaxy Rasbora remains especially widespread in Canada. Because its natural range is localized, aquarists working to maintain a consistent line should avoid mixing fish from different strains or collection sources without a clear breeding plan.

Appearance and physical characteristics

The body of Celestichthys margaritatus is short, deep and slightly compressed from side to side. Its base color ranges from blue gray to almost black, with numerous irregular pearly white spots resembling a starry sky. Males often develop stronger colors, an orange-red breast and red fins edged with dark areas; females are paler, stockier and have a rounder abdomen. The dorsal and anal fins may show contrasting black and red margins. This species reaches about 2.5 cm as an adult, sometimes less depending on the strain and growing conditions. Its small mouth limits the size of food it can swallow.

General diet

Celestichthys margaritatus is a small omnivore with an insect-eating tendency. In nature, it captures tiny aquatic organisms and likely consumes part of the microfauna found among vegetation. In the aquarium, its diet should include fine foods such as newly hatched brine shrimp, small daphnia, cyclops and finely chopped frozen foods. Quality dry food, crushed into powder or offered as micro-pellets, can complete the diet. It is better to feed small portions regularly so every fish can eat without allowing leftovers to pollute the water. A varied diet helps maintain coloration, body condition and breeding success.

Essential data

• Name of the native river: Nam Lang
• Local name used: Galaxy Rasbora, Celestial Pearl Danio, Galaxy Rasbora
• Origin of the scientific name: The genus Celestichthys refers to the fish’s celestial appearance; the species name margaritatus refers to its pearl-like spots.
• Etymology of the full name: Celestichthys means celestial fish; margaritatus means pearl-adorned or pearly.
• Common/vernacular names: Galaxy Rasbora, Celestial Pearl Danio
• Family: Danionidae
• Subfamily: Danioninae
• Name pronunciation: seh-les-tik-this - mar-gar-i-TAH-tus
• Discovery: Tyson R. Roberts, 2007
• Maximum adult size: About 2.5 cm
• Water temperature and pH: 20 to 26 °C; pH 6.5 to 7.5
• Watercourse appearance and surrounding vegetation: Small, shallow, still waters ranging from clear to lightly stained, bordered by aquatic plants, submerged grasses and plant debris.
• Typical tank companions: Small peaceful danionins, dwarf rasboras, calm small characins, adult shrimp and aquarium snails.
• Temperament and behavior: Peaceful, schooling and intermittently active; males display and briefly chase one another.
• Water depth: Generally shallow, often less than 50 cm in known habitats.
• Sexual dimorphism: Males are more colorful and slender; females are rounder, paler and fuller through the abdomen.
• Bottom structure and flow: Muddy or sandy-muddy bottom covered with plant matter; no current to very slow flow.

In your aquarium

To succeed with Celestichthys margaritatus, choose a mature aquarium with plenty of plants and sheltered areas. Stable water, moderate filtration and a sufficiently large group reduce stress. Food should be very fine and offered in small portions. Avoid large fish and boisterous species that could easily outcompete it for food. A moderate temperature of about 22 to 24 °C works well for everyday care. With regular water changes, slightly subdued lighting and dense vegetation, this small fish displays its pearly spots and its most interesting social behavior.