Indoor vs. Outdoor Medaka Keeping — Which Environment Is Best?

When starting medaka keeping, many wonder whether to go with an indoor aquarium or an outdoor tub or water lily pot. Let's compare the pros and cons of each.

Basic Differences

• Indoor Keeping: Tank + filter + lighting. Consistent environment year-round
• Outdoor Keeping: Plastic tub, water lily pot, or foam box. More natural environment

Equipment and Cost

Indoor Keeping - Tank (30–60cm): 2,000–10,000 yen - Filter: 1,000–3,000 yen - Lighting: 2,000–5,000 yen - Heater (for winter breeding): 1,000–3,000 yen - **Monthly electricity**: 500–1,500 yen

Outdoor Keeping - Plastic tub (40–80L): 1,000–3,000 yen - Water lily pot: 2,000–10,000 yen - **Monthly electricity**: 0 yen

Outdoor keeping has an overwhelming cost advantage.

Viewing Experience

• Indoor: Side-view observation. Enjoy planted aquascaping. Beautiful under lighting
• Outdoor: Top-down viewing (uwami). Natural sunlight brings out the medaka's true body coloring

For aquascaping, choose indoor. For maximizing body color appreciation, outdoor top-down viewing is best.

Water Quality Management

• Indoor: Water quality maintained by filter. Regular water changes needed (weekly)
• Outdoor: Natural purification through green water and aquatic plants. Water changes needed less frequently

Outdoor keeping is easier to manage. Natural cycles help stabilize water quality.

Breeding

• Indoor: Year-round breeding possible with heater and lighting. Easier fry management
• Outdoor: Natural breeding from April–October. Green water increases fry survival rates

For year-round breeding, choose indoor. For natural breeding cycles, choose outdoor.

Seasonal Management

Indoor Keeping - Spring–Autumn: Stable water temperature. Normal care - Winter: Maintain water temperature with heater. Breeding also possible

Outdoor Keeping - Spring: Breeding season begins. Install spawning mops - Summer: Watch for high temperatures (shade with reed screens). Beware of temperatures exceeding 35°C - Autumn: Breeding season ends. Prepare for winter - Winter: Even if the surface freezes, as long as the bottom doesn't freeze, they'll be fine. No feeding needed

Surprisingly, outdoor keeping is less labor-intensive (winter is hands-off). However, summer heat management is necessary.

Predators and Risks

• Indoor: No predator concerns. Watch for water leaks
• Outdoor: Birds, cats, dragonfly larvae (yago), mosquito larvae. Use netting for protection

Indoor is safer. Outdoor requires netting or covers for protection.

Who Should Choose Which

Indoor keeping is recommended if you: - Want to enjoy planted aquascaping - Want year-round breeding - Don't want to worry about predators - Want to observe medaka from the side

Outdoor keeping is recommended if you: - Want to minimize running costs - Want to enjoy a biotope atmosphere - Want to reduce maintenance effort - Want to see medaka's true colors under sunlight - Want to keep many varieties (easier to secure space)

Benefits of Buying on Buri-Choku

On Buri-Choku, you can purchase directly from specialist medaka breeders. They can recommend suitable varieties for indoor or outdoor keeping and provide care advice, giving beginners peace of mind.