Don't buy ducklings from the markets or a pet shop or something like that. They will most likely be muscovy's. Muscovy's are the large white ducks with the red markings around the face. They don't lay eggs in any number, tend to be aggressive and poo more than you can possibly believe. If you do choose to get ducks, and they are a great animal, get some pekins, indian runners or khaki campbells from a breeder. If you get ducklings, you take a chance on getting a duck or drake, but if they are just for pets then with these breeds, that doesn't really matter. As greg said, they eat layer pellets and veggie scaps. They will also mess their water up every time you clean it so it is important to give them clean water at least once a day.