Galaxy Rasbora (Celestial Pearl Danio) Care Guide

The Galaxy Rasbora (scientifically known as Danio margaritatus), also referred to as the Celestial Pearl Danio, is a strikingly beautiful, small freshwater fish native to Southeast Asia. Despite being commonly known as a rasbora, this species is more closely related to danios. With its iridescent blue body and vivid orange or red fins, the Galaxy Rasbora is a favorite among aquarists, especially those who keep nano tanks. Their peaceful nature, coupled with their stunning appearance, makes them a popular choice for well-planted community tanks.

Natural Habitat and Origins

The Galaxy Rasbora was first discovered in 2006 in a small region of Myanmar (Burma) in the Shan State. It inhabits shallow, densely vegetated ponds and slow-moving waters in high-altitude areas. These waters are rich in aquatic plants, and the fish thrive in environments with thick vegetation, which provides them shelter and breeding areas.

Their natural habitat has slightly acidic to neutral water conditions, with cooler temperatures compared to tropical lowland rivers. These environmental preferences should be replicated in the home aquarium to ensure their well-being.

Appearance and Size

The Galaxy Rasbora is one of the most visually striking small fish available in the aquarium hobby. It has a deep blue or dark green body speckled with pearly, galaxy-like white spots, giving it a celestial appearance, hence its common name. The males typically have more vibrant colors, with bright orange or red fins outlined in black. Females are slightly duller, with less pronounced fin colors and a rounder body, especially when full of eggs.

These tiny fish reach a maximum length of about 1 inch (2.5 cm), making them perfect for nano tanks or as peaceful additions to planted community tanks.

Aquarium Setup and Care

• Tank Size: Despite their small size, Galaxy Rasboras are active swimmers and prefer to be kept in groups. A minimum tank size of 10 gallons (38 liters) is recommended for a small group of 6-8 individuals, but a larger tank (20 gallons or more) is ideal if you plan to keep a larger school or include other species.
• Water Parameters: To replicate their natural environment, the following water conditions are ideal:
  • Temperature: 68-78°F (20-25°C). They can tolerate slightly cooler water than many tropical species.
  • pH: 6.5-7.5 (slightly acidic to neutral)
  • Water hardness: Soft to moderately hard (1-10 dGH)

Keeping the water clean is essential, as Galaxy Rasboras are sensitive to poor water quality. Regular water changes of about 25% weekly will help maintain optimal conditions.

• Aquascape: The ideal setup for Galaxy Rasboras mimics their natural habitat, with dense vegetation and plenty of hiding spots. Live plants such as Java Moss, Anubias, Cryptocoryne, Dwarf Hairgrass, and Rotala work well in their tank. These plants provide shelter, reduce stress, and create a natural-looking environment for the fish.

Adding driftwood and rocks will further enhance the tank’s aesthetics and provide additional hiding spots. Keeping some open areas for swimming in the middle and upper levels of the tank is also important, as they are active fish that enjoy exploring.

• Filtration: A gentle filtration system is best for these small fish. A sponge filter or a low-flow internal filter is recommended to avoid strong currents that may stress them out. Galaxy Rasboras prefer calm, slow-moving waters, so it’s important to avoid turbulent water conditions.

Feeding

Galaxy Rasboras are omnivores and are not picky eaters. In the wild, they feed on small invertebrates, zooplankton, and plant matter. In an aquarium, they will accept a variety of foods:

• High-quality micro pellets or fine granules
• Live or frozen foods such as daphnia, brine shrimp, and bloodworms
• Flake food (crushed to small sizes)
• Freeze-dried foods

It’s best to provide them with a varied diet to ensure they receive all the nutrients they need for vibrant colors and overall health. Feed small amounts 1-2 times a day, making sure that all food is consumed quickly to prevent it from sinking to the substrate and fouling the water.

Temperament and Behavior

Galaxy Rasboras are peaceful, schooling fish that thrive in groups. It’s recommended to keep at least 6-8 individuals together, as this helps them feel secure and reduces stress. When kept in larger groups, males will display vibrant coloration and engage in harmless, competitive displays to attract females, adding to the visual appeal of the tank.

They are relatively shy and may take some time to become comfortable in their new environment. Dense planting and a quiet tank will help them feel secure and exhibit more natural behavior.

Best Tank Mates for Galaxy Rasbora

Due to their small size and peaceful nature, Galaxy Rasboras should only be housed with other peaceful, non-aggressive species. Ideal tank mates include:

• Small tetras (like Ember Tetras)
• Other small rasboras (such as Chili Rasboras or Strawberry Rasboras)
• Dwarf Corydoras (like Pygmy Corydoras)
• Dwarf shrimp (such as Cherry Shrimp or Amano Shrimp)
• Otocinclus Catfish

Avoid keeping them with larger, more aggressive species that might see them as prey. Additionally, tank mates that are too active may stress them out, so it’s best to pair them with other calm fish.

Breeding

Breeding Galaxy Rasboras is possible in the home aquarium, though it requires attention to detail. They are egg scatterers, meaning they lay their eggs among plants and substrate rather than protecting them.

To encourage breeding, provide dense plant cover, particularly fine-leaved plants like Java Moss or spawning mops. These plants will give the eggs a safe place to hide from adult fish, which may eat the eggs if given the opportunity. Males will display bright colors to court females, and when a female is ready to spawn, she will scatter her eggs among the plants.

After spawning, it’s best to remove the adult fish to prevent them from eating the eggs. The eggs will hatch in 2-3 days, and the fry can be fed infusoria or commercially available fry food until they are large enough to eat baby brine shrimp.

Conclusion

The Galaxy Rasbora is a stunning, peaceful, and easy-to-care-for fish that is perfect for nano aquariums and planted tanks. Their small size and vibrant colors make them a centerpiece of any tank, while their peaceful temperament makes them ideal for community setups with other small, non-aggressive species. With the right care and environment, Galaxy Rasboras will thrive, providing endless enjoyment for both novice and experienced aquarists alike.