Galaxy Danio (Celestichthys Margaritatus )

Tiny, dazzling, and utterly captivating — the Galaxy Danio (Celestichthys margaritatus), also known as the Celestial Pearl Danio, is one of the most breathtaking nano fish in the freshwater hobby. Discovered in Myanmar in 2006, this little gem took the aquarium world by storm with its deep blue body adorned with pearl-like spots and vivid red-orange fins. A true jewel for planted nano tanks.

Overview

Appearance

The Galaxy Danio features a rich dark blue body covered in small, iridescent white spots resembling a starry galaxy. Males display vivid red-orange stripes on their fins and show more intense colouration overall, especially when in spawning condition. Females are slightly rounder and paler but equally attractive. A group of these fish shimmering through a planted tank is a truly mesmerizing sight.

Water Parameters & Tank Setup

• Temperature: 73 – 79°F (23 – 26°C)
• pH: 6.5 – 7.5
• General Hardness (GH): 2 – 10 dGH
• Tank Size: Minimum 10 gallons for a group of 8+
• Lighting: Moderate; colours pop beautifully under good lighting
• Substrate: Dark, fine-grained substrate to enhance their colouration
• Plants & Decor: Dense planting with open swimming areas — Java moss, Riccia, and stem plants are ideal

Diet & Feeding

Galaxy Danios are micro-predators in the wild and thrive on small foods:

• Staple: High-quality micro pellets or nano fish flakes
• Treats: Micro worms, baby brine shrimp, daphnia, and cyclops
• Avoid: Foods too large for their tiny mouths

Feed small amounts 2–3 times daily.

Compatibility & Tank Mates

Best kept in groups of 8 or more to encourage natural schooling behaviour and reduce shyness. Ideal tank mates include:

• Other nano fish (Chili Rasboras, Ember Tetras, Pygmy Corydoras)
• Dwarf shrimp (Neocaridina and Caridina species)
• Small snails

Avoid housing with larger fish that may see them as food.

Breeding

Galaxy Danios are egg scatterers and will spawn readily in a well-planted tank. They prefer to deposit eggs among fine-leaved plants or moss. Parents may eat eggs, so a separate breeding tank or dense moss coverage is recommended. Fry hatch within 3–4 days and can be fed infusoria or commercial liquid fry food initially, graduating to micro worms and baby brine shrimp.

The Galaxy Danio is proof that great things come in small packages. Add a group to your nano or planted aquarium and enjoy the living constellation they create.