I would suggest a really good filtration system. If you could set it up that the pond has a continuous fresh water input. Just a few gallons a hours with an over flow to take out excess water. That would be key to keeping fish alive inside for so long. Otherwise nitrate and ammonia levels would go through the roof. You can then always use an autofeeder for daily feeding. You can get a filter cylinder from any hardware store that would remove heavy metals and chlorine from tap water.

Hope this helps....Craig

Craig

I greatly appreciate your suggestion, Craig. Unfortunately, I don't have the ability to have a fresh water flow and replacement option for our 1500 gallon pond during the freezing Michigan winter. I actually think I have reached a solution... I am going to temporary place the koi in a large tub with good air circulation, and have the pond dismantled and relined during a two day period. It's going to be a haul, but then I will be able to winter them over with multiple bubblers as I have in previous years. Thanks again!!

Anytime, I've seen from past experience of placing fish in a quarantine system for long periods that a fresh water intake is essential. Good luck!!!