Duckweed can be a major problem if it is allowed to grow without any restrictions on a small, still pond or lake. Moving water can help to deter the growth of duckweed but in some ponds it is not possible to have moving water. In these cases one option to control duckweed is to use animals that will eat duckweed as a food source. There are many different animals that regularly eat duckweed and that can be introduced to your pond to help contain its growth. Ducks, (obviously), fish, geese, turtles, and other animals are all known to eat duckweed. Having some of these animals living in or around your pond can have a noticeable difference in the surface coverage of duckweed and pond health.
So what animals eat duckweed?
Many tropical and freshwater fish are known to eat duckweed when it is found in their environment. In fact the duck-weed plant is a favorite food source for tilapia and carp fish farmers. Tilapia in particular are a great fish for controlling duckweed growth due to their own fast growth rate, and their voracious appetite for duckweed and other aquatic plants. At the end of the year you can even harvest your Tilapia before your pond freezes for a great fish meal. Before introducing fish to any pond or body of water make sure you check your local rules and regulations, as it is illegal to introduce non-native fish in some areas.
Waterfowl such as ducks and geese can also eat enough duckweed to help to control it, but these animals alone are generally not enough to keep duckweed in check, and often additional methods and/or other animals are needed to keep a pond healthy.
There are also many mammals that make duckweed a major part of their diet. Some North American examples are muskrats, beaver, woodchucks, and other small rodents. Reptiles and amphibians also occasionally eat duckweed. Snakes, turtles, and frogs are all known to eat the duckweed plant. However like waterfowl, these animals are generally not enough to control duckweed by themselves, but when combined with other methods and animals they can be part of a comprehensive pond duckweed control plan.
So if duckweed is taking over your pond, making an ugly, smelly eyesore, consider some natural weed control methods before resorting to more expensive, and potentially harmful chemical treatments.
Please visit the author’s site for more information on how to control duckweed, as well as more in depth information about what animals eat duckweed and other methods for removing duckweed from your pond or lake.