Winter Care Guide for Outdoor Medaka

Medaka are cold-hardy and can overwinter even when the water surface freezes. However, proper preparation is needed.

When to Stop Feeding Begin reducing food when water temperature drops below 15°C. Stop completely below 10°C. Undigested food causes water quality deterioration.

Keep Water Volume High Greater volume means more gradual temperature changes. Top off water before winter to raise water levels. At least 10L recommended.

Surface Freezing Measures Surface ice is fine as the bottom won't freeze. However, complete freezing is fatal. Styrofoam containers resist freezing and are ideal for overwintering.

Minimize Water Changes Water changes are basically unnecessary in winter. Only top off evaporated water. Sudden water quality changes cause stress.

Relocate Containers Move to locations sheltered from direct wind. Avoid spots exposed to north winds. Under eaves or garage entrances are ideal.

Remove Fallen Leaves and Debris Fallen leaves entering containers cause water quality deterioration. Cover with netting to prevent this.