Midwest Pond and Koi Society - Q&A #158

I am a first year Koi owner having inherited a large Koi, about nine inches, and five smaller ones. I built a 6' by 9' pond, about 21/2 feet deep and now it is September here in Minnesota. I don't want to try to heat the pond but when do I transfer them indoors and what size tank do I get? It is getting down to a high of 50 here some days this week.

Hi, Marsha,

Your koi are probably small enough to come indoors, but you'll need at least a 250 gallon horse trough from Farm 'n Fleet to house them. Move your current pond's filter system in with it (basement or heated garage is best) and get it running as your water temperature approaches 55 degrees F. You'll need a good air pump as well. Your current pond holds about 1000 gallons, so as long as you feed very sparingly and do frequent water tests and changes, the 250 gallons should be enough. Keep your tank's water temp at or above 60 degrees. This will give you a great start on an isolation and medical tank system for next year.

Alternatively, you could purchase a greenhouse kit from a landscape supply outfit and cover the pond. Something that small should do well with a 30 dollar electric radiator stuck under the cover. All that's needed is to keep the water temp above freezing and aerated well. You can shut down your filters as water temps drop below 50 degrees. Pull out or drain your pumps and pipes to prevent freezing damage.