Hello, according to the research I have found, barley is not harmful to ducks, wheat is, and bread is not recommended, but barley is safe and some sites such as birding.about.com recommend barley as a good food source. However, being a pond owner myself (I am not a Master Gardener nor an expert in this field) I have used barley to reduce algae in my pond and I presume that is your purpose for using barley in a pond in the first place. Pelllets may appear as food to ducks. I have also had ducks in my pond for several years. Depending on the content of the pellets (grain vs straw) they might not much nutirtional value out of barley, and ducks eating the pellets would mitigate the purpose of the barley in the first place (algae reduction). The pellets on the market I have seen dissolve quickly and are tossed into the open water. But ducks are fast eaters! Consider placing the pellets in a porous bag (net or pond bag) or container so the ducks cannot access them/confuse them as food. Hope this helps!