Good deal having AC electricity. That makes installing aeration much simpler and much less costly.
Dissolved oxygen in water is also a function of temperature. Cool water can hold significantly MORE oxygen. I think your plan of maximizing the input of cool, naturally aerated river water should be a great benefit to your fish.
Hopefully, that will get your fish through this crisis period.
To avoid a future crisis, you might want to start a new thread in the Aeration sub-forum and post your pond circumstances. You should be able to get some really good advice from the Pond Boss experts on that topic.
