Hornwort also known as Coon Tail for its puffy, long structure, is an excellent choice for a sustainable food source for ducks which can easily be grown with or without a duck pond. Since Hornwort does not need to be planted and grows in the water column as a floating, yet submersed, plant, simply breaking off a piece of it will start a whole new plant. This comes in handy as whatever is left behind by the ducks will regrow itself into more and more plants, which means you can grow more and more of it in plastic tubs or other ponds, where it will help to keep the water clean by absorbing nutrients from the water.