I used to have pond in the front yard with some feeder fish that grew to be about 4-6". Instead of coons going after the fish, we had the neighbors kids throwing rocks at them or trying to steal the fish.
As for coons, we have squirrels running around the gutters so we set up little traps with nuts in them so we can relocate the squirrels. I never knew we had coons in the area until we set those traps! We've caught like 5 or 6 coons in the last 3 months and no squirrels!
If you ever find a way to get rid of the coons, let me know! good luck!