Medaka Outdoor Pond & Biotope Guide

Outdoor biotope keeping lets you enjoy medaka in a near-natural environment. Sunlight and natural cycles promote healthy growth that is hard to replicate indoors.

Choosing a Container

• Ceramic water lily bowl: Beautiful appearance. At least 40 cm diameter recommended
• Plastic utility tub: Cost-effective with large capacity. Ideal for breeding
• Styrofoam container: Excellent insulation for winter. Inexpensive way to start

Allow 1–2 liters of water per fish, with a minimum depth of 15 cm.

Recommended Plants & Placement

Floating Plants - Water hyacinth: Excellent summer shade. Roots serve as spawning medium - Amazon frogbit: Small and easy to manage

Submerged Plants - Anacharis: Hardy and beginner-friendly. Excellent water purification - Hornwort: Simply float it — no planting needed. Also works as spawning medium

Emergent Plants - Sagittaria: Produces white flowers - Water mushroom: Charming round leaves

Seasonal Management

Spring (March–May): Begin feeding once water temperature exceeds 15°C. Install spawning mats in preparation for breeding season.

Summer (June–August): Temperature control is the top priority. Use reed screens and floating plants for shade, keeping water below 35°C. Top off frequently to compensate for evaporation.

Fall (September–November): Remove fallen leaves regularly. Gradually reduce feeding as temperatures drop.

Winter (December–February): Stop feeding entirely when water temperature falls below 5°C. Medaka can overwinter as long as the water doesn't freeze solid to the bottom. Do not change water.

Predator Protection

• Birds (crows, herons): Cover containers with netting or wire mesh
• Cats: Secure netting or install cat deterrents
• Dragonfly larvae (yago): The biggest threat. Regularly check container bottoms and remove them
• Water striders: Prey on fry — cover fry containers with fine netting

See also our Medaka Color Genetics Guide.

Find Medaka on Bri-Choku

Bri-Choku offers a wide selection of hardy medaka suitable for outdoor keeping. Browse the medaka category to find biotope-friendly varieties.