My neighbor has a 1/4, maybe 1/3 acre pond. He put 2 white ducks in it. After a few months he noticed the shore was being eroded by their dabbling among the grass roots, and the pond was muddy. Coyotes or owls got the ducks and the pond cleared up in less than 2 weeks, and the erosion stopped. That was 2 years ago and he hasn't even thought about replacing the ducks.
