Preparing Your Koi for a Canadian Winter
As temperatures fall, your koi slow down and enter a dormant state. A little preparation in autumn makes all the difference for a safe overwintering.
Autumn Prep
- Switch to a wheat-germ cold-water food as temperatures drop, and stop feeding entirely below ~8°C.
- Remove leaves and debris before they sink and decay — a pond net over the surface helps.
- Clean your filter and trim back dying plants.
Keeping the Pond Open
The single most important winter task is keeping a hole open in the ice so toxic gases escape and oxygen enters. Use a floating de-icer paired with an air stone placed at mid-depth. Never smash the ice — the shock waves can injure dormant koi.
Equipment Through Winter
In most Canadian climates, run the de-icer and aeration continuously. Many keepers shut down the main pump and UV to avoid super-chilling the deep water where koi rest. Know your pond depth — koi overwinter best in ponds at least 90 cm (3 ft) deep.
Spring Wake-Up
As water warms past 8–10°C, resume gentle wheat-germ feeding and restart filtration. Dose beneficial bacteria to jump-start your biological filter for the season ahead.