Celestial Pearl Danio

The celestial pearl danio (sold as the galaxy rasbora, though scientifically a danio) was discovered in 2006 and quickly became popular worldwide. Its dark blue-green body is covered with pearl-like golden spots; its fins have orange-red and black stripes. The males' belly and fins are bright red-orange.

It is a small, shy fish: it looks its best in a densely planted, quiet nano aquarium.

It lives in shallow, densely vegetated ponds and marshes fed by spring water on Myanmar's high plateau. The water is clear, moderately hard and relatively cool.

• Volume: 30 liters or more for a group of 8–12.
• Plants: very dense planting (moss, fine-leaved plants, floating plants); it is bolder when there is little open space.
• Water: 22–25°C, neutral and moderately hard. Gentle flow is enough.
• Tankmates: it does very well in shrimp tanks; large, active fish drive it into hiding.

Omnivorous, but its mouth is very small. Micro granules, finely crushed flakes, frozen cyclops, newly hatched brine shrimp and daphnia. Newly arrived fish usually accept live or frozen food first.

Peaceful and shy; rather than schooling, it moves in a loose group. Males display to each other by flaring their fins and have short chases; this is natural.

Good companions: red cherry and other Neocaridina shrimp, otocinclus, harlequin rasboras, small corydoras (C. pygmaeus, C. habrosus), nerite snails.

Avoid: large, active fish, bettas (depending on the individual), any fish with a mouth big enough to swallow it.

At least 8, ideally 12 or more individuals; a female-heavy group is the most balanced arrangement. Celestial pearl danios kept in small numbers almost always hide. The males' display sparring softens as the number of females increases.

It spawns on its own in an aquarium with plenty of moss; the eggs are laid among the moss and plants. The parents eat the eggs, but in very dense moss some fry survive. The fry are very small and are fed infusoria and microworms.

• Starvation: newly arrived fish may refuse dry food; start with live and frozen food.
• Stress and hiding: in an open, unplanted aquarium.
• It is generally hardy but does not like sudden water changes.

Males are more brightly colored: red-orange belly and fins, dark blue body. Females are paler, with a greenish body, and plumper; their fins are pale orange. Mature females show a dark spot in front of the ventral fin.