They don t sit completely still all winter they need a little movement to keep their joints from seizing up.
Outdoor koi pond in winter.
The basic principle for winter pond care is as long as the water is circulating and there is an air hole to allow oxygen in and gases out fish and plants should be fine.
They can survive water temperatures as low as 0 c which means they can survive in the pond during the winter as long as it doesn t freeze solid and they have adequate water quality and oxygen.
To help ensure healthy fish in the spring follow these steps.
Goldfish and koi are very hardy fishes.
It doesn t matter how deep the pond is it just matters that the water is moving and not frozen.
In the wintertime when the water in your pond is ice cold the koi fish s metabolism slows down to a crawl.
Non hardy plant specimens such as tropical water lilies can be moved out of the backyard pond in winter and into a greenhouse or under artificial lights for 12 to 18 hours with a water temp of around 70 f.
That leaves 16 for the fish to lounge around and basically hibernate over the winter.
Goldfish and koi can survive winter outdoors so long as ponds don t freeze completely freeze solid.
21 c or they may be stored as a dormant tuber.