Celestichthys Margaritatus (Galaxy Rasbora)

Aquarium Livestock
8 Nov 00:00

Galaxy Rasbora

Common names: Galaxy Rasbora / Fireworks Rasbora / Celestial Pearl Danio

Scientific name: Celestichthys Margaritatus


This fish is not really a Rasbora and is more closely related to the Danios'. A fairly recent introduction to the hobby – only discovered in 2006, it has caused a real stir and it truly is one of the most stunning fish available. As an added bonus, they are also very easy to keep and breed.

Sexing:  This is pleasingly easy. Males are much brighter and develop much more intense red on their body when in breeding condition (which is most of the time as they are frisky)!

Size: 2cm

Where are they from?: Mynamar and Northern Thailand – once thought to come from a single pool, they are now known to have a wider distribution.

Their natural habitats are spring-fed pools with lots of vegetation.

Aquarium size: Minimum 45cm x 30cm x 30cm.

Aquarium conditions: Very easy to keep. Good clean water is important, but they are not fussy with regard to hardness or pH. Filtration should not be too vigorous, air powered sponge filters are great, or very small internal power filters.

Temperature can be anywhere from 20-28 degrees, so they can be kept cooler than many common species.

They are most interesting if kept in a group as they display really entertaining behaviour with males constantly displaying. A well planted tank looks good and provide places for sub dominant males to get away.

They are very small fish, so should have similar sized tank mates. Small Rasboras work well, although any other small fish like Neon Tetras are also OK. However, they do need areas to display, so make sure that there is enough space. They also look great with many small shrimp species.


Egg scattering spawner’s, water parameters are not critical and they will usually spawn in the display aquarium. It is sometimes possible to keep a breeding colony. If there is plenty of covering, some young will survive and make it to adulthood.

They are best spawned in a separate breeding aquarium set up for specifically this purpose.

Ideally, separate the two sexes and condition them by feeding a variety of food including frozen and live food if you have access to it. You want them to be fit and healthy and feeling frisky. This species will breed at temps as low as 20 degrees C, so you may not even need a heater to spawn them.

The tank can be quite small – 30 x 20 x 20cm works well. You can use a pair or a small group. The eggs are slightly sticky, so you need to have a big wodge of fine leaved plants like Hornwort, Cabomba or Elodea to catch the eggs. This will also reduce the chances of the eggs getting eaten as well. If you prefer, you can use woolen mops in place of plants.

Spawning usually occurs in the morning – remove the parents afterwards. The eggs should hatch in 72-96 hours (quicker at higher temps, longer at lower temps). The babies will then feed off their yolks until they become free swimming (usually about 3 days). At this point start to feed them with small foods. Live foods are great, but commercial liquid and dried foods are perfectly acceptable for them – just be very careful not to overfeed.

Final comments/Key points

  • Tiny jewels, very easy to keep.
  • One of the most poetic yet accurate scientific names ever: Celestichthys Margaritatus means “heavenly fish covered in pearls”.
  • A great fish for a breeding project.
  • Sometimes they arrive in poor condition – place in a mature aquarium and feed regular amounts of small foods and they should come round quickly - but don’t buy very thin specimens!


Author & Photo credit - Parkers Manager Patrick Davies.