Celestial pearl danios (galaxy rasboras): discovery and care

When they were discovered

Celestial pearl danios (Danio margaritatus) were described by scientists in 2007, after being found in a small area of Myanmar (Burma) the year before. They caused a sensation: a tiny, brilliantly coloured fish that had gone unnoticed until then. The common name “galaxy rasbora” stuck early, though they’re actually danios, not rasboras. The scientific name margaritatus means “adorned with pearls,” referring to the pearlescent spots on their flanks.

Where they come from

They inhabit shallow, heavily vegetated ponds and ditches in the Shan state of Myanmar — cool, clear, plant-rich water. The wild population is limited and has faced pressure from collection. Captive-bred fish are now widely available and are often hardier than wild-caught ones. Buying captive-bred also reduces pressure on wild stocks.

Care basics

• Tank size: A 10–15 gallon (40–60 litre) tank is enough for a small group. They’re nano fish but active; cramped quarters stress them.
• Water: Cool (around 72–76°F / 22–24°C), neutral to slightly alkaline. They tolerate a range but prefer stability.
• Setup: Dense planting, floating plants, and hiding spots. They feel secure in a planted tank and display better.
• Group size: Keep at least six, preferably more. They are social and less shy in a group.

Behaviour and temperament

Males can spar and display to each other — usually harmless, but ensure enough space and cover so no single fish is harassed. They are generally peaceful with other small, non-aggressive species. Avoid large or boisterous tank mates. They appreciate calm water and are often seen mid-water or near plants.

Feeding

They take small pellets, micro pellets, and frozen foods (e.g. baby brine shrimp, daphnia). Variety helps. They are not picky but do best with regular, small feeds rather than one large meal.

Quick takeaways

• Discovered in Myanmar in 2006–2007; caused a sensation in the hobby.
• Cool, planted tanks; keep in groups of six or more.
• Captive-bred fish are widely available and often hardier than wild-caught.