Red cap Koi Ricefish (Medaka)

Red Cap Koi Ricefish Medaka (Oryzias latipes – Red Cap Koi Variety)

Inspired by the elegance of traditional koi, the Red Cap Koi Medaka is a charming and eye-catching ricefish variety that features a crisp white body adorned with a vivid red cap on the head — a pattern that mirrors the iconic Tancho koi. Compact in size but big in personality, these little fish bring the beauty of a koi pond into even the smallest aquarium or outdoor tub. A favourite among medaka enthusiasts and koi lovers alike.

Fish Details

• Adult Size: 3–4 cm (1–1.5 inches)
• Temperament: Peaceful, active schooling fish
• Diet: Omnivore — accepts high-quality flake food, micro pellets, and small live/frozen foods (baby brine shrimp, daphnia, micro worms)
• Lifespan: 2–4 years
• Breeding: Egg layer — females carry egg clusters and deposit them on plants or spawning mops; eggs hatch in 10–14 days

Tank Requirements

• Minimum Tank Size: 40 L (10 gallons)
• Water Temperature: 18–26°C (64–79°F) — adaptable; tolerates cooler temperatures well
• pH: 7.0–8.0
• Water Hardness: Moderately hard to hard
• Lighting: Moderate to bright — makes their red cap and white body pop beautifully

Compatibility

• Best kept in groups of 6 or more for natural schooling behaviour
• Ideal tankmates: other medaka varieties, small rasboras, corydoras, snails, and freshwater shrimp
• Avoid housing with large or fin-nipping fish
• Excellent for outdoor tubs or ponds during warmer Canadian months — their koi-like pattern is stunning viewed from above

Care Tips

• A dark substrate makes their white body and red cap stand out dramatically
• Floating plants like water lettuce or frogbit provide shade and a natural feel
• Easy to breed — add a spawning mop or fine-leaved plants and they will readily spawn
• Perform regular water changes of 20–30% weekly to maintain optimal health and colour
• Keep the tank covered — medaka are known to jump

All the charm of a koi pond in a tiny, easy-to-keep package — the Red Cap Koi Medaka is a delightful and unique addition to any aquarium or outdoor water garden.