Description
Red Cap Medaka (Oryzias latipes), also known as Japanese Rice Fish, is a colourful and hardy freshwater species prized for its peaceful nature and adaptability. The Red Cap variant is particularly striking, featuring a clean white or translucent body accented by a vivid red-orange spot on the top of the head—resembling the iconic Red Cap Oranda goldfish. Native to East Asia, Medaka are active, surface-oriented swimmers that thrive in both indoor aquariums and outdoor ponds.
Features of Red Cap Medaka
• Grows up to 3–4 cm in length
• Distinct white or translucent body with a bright red cap on the head
• Peaceful, social, and best kept in groups of 6 or more
• Active top-level swimmers
• Hardy and highly adaptable to a range of water conditions
• Lifespan of 2–4 years with good care
The best aquarium size for Red Cap Medaka
A minimum of 30 litres is suitable for a small group. For optimal health and natural behaviour, provide a larger tank (60 litres or more) with horizontal swimming space and a gentle surface current. Red Cap Medaka also do well in outdoor setups or patio ponds in temperate climates.
Tank Mate Compatibility for Red Cap Medaka
• White Cloud Mountain Minnows
• Cherry Shrimp
• Nerite Snails
• Endler’s Livebearers
• Otocinclus Catfish
Diet for Red Cap Medaka
These fish are omnivorous and require a balanced diet of fine flakes or micro pellets. Supplement with live or frozen foods such as baby brine shrimp, daphnia, and microworms to enhance colour and activity. Feed small amounts once or twice daily, avoiding overfeeding to maintain water quality.
Aquarium Setup Red Cap Medaka
Aquarium Filtration
Use a gentle sponge or hang-on-back filter to maintain water clarity without strong currents. Red Cap Medaka prefer still or slow-moving water. Perform regular water changes and keep parameters stable.
Aquarium Plants
Live plants such as Hornwort, Java moss, and Water Sprite are ideal. Floating plants like duckweed or Salvinia offer shade and mimic their natural habitat. Plants also provide shelter for fry.
Aquarium Lighting
Moderate to low lighting enhances their red cap and creates a calm environment. If kept outdoors, natural light is sufficient, but provide shaded areas to prevent overheating.
Aquarium Heating
Red Cap Medaka tolerate a wide temperature range (15–28 °C), but thrive best between 20–24 °C. Heating may not be necessary in room-temperature tanks, but monitor for seasonal changes.
Aquarium Substrate
Use fine gravel or sand for ease of maintenance and to support plant growth. Substrate colour can contrast beautifully with their pale body and red cap.
Aquarium Decorations
Include small stones, driftwood, and dense vegetation to provide hiding places and visual interest. Avoid sharp objects that may damage their delicate fins. Open swimming space at the surface is essential for their natural behaviour.
