I wouldn't throw in the towel yet and assume that you're going to have a fish kill.

There are plenty of things you can do to move the water around. Pumps, boat motors, etc.

Whatever you do, you should start gradually.

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."