I have a low area that im thinking of making into a small pond about 20 feet wide by 20 feet wide. Maybe 3-4 feet deep. I don't mind a cute little picket fence around it but i'm not looking to build a completely closed in pen for ducks. I want to keep it open. I have chickens but no ducks. Is it possible to have ducks in fenced but open area ( i mean no ceiling) ?