Many varieties of aquarium fish, such as goldfish, tilapia, and common pleco will eat duckweed. Adding these or other fish to your tank is one way you can control its growth and have a built-in food source. Other aquatic pets, such as certain types of turtles will also eat it.
What Type of Fish Eats Duckweed?
In addition to goldfish, common pleco, and tilapia, pond fish such as koi and some smaller tropical fish will eat duckweed. Grass carp, common pleco, and Ameca Splendens also feed on it. However, if you only have a few of the smaller fish, they won’t eat enough to keep the growth under control.
If you are attempting to use duckweed as an ongoing food source, then smaller fish are good choices for your tank. Koi, on the other hand, will eat it rapidly and are therefore a great fish for getting rid of it altogether.
Is Duckweed Good for Your Aquarium?
Some people want duckweed because it acts as an excellent water filter and can save owners from using water purifiers. Since it will cover the water surface and block excessive light, it is also an excellent way to reduce algae in your tank.
Another advantage of duckweed covering the water’s surface is that it provides shade for aquatic life. It helps prevent too much light from reaching plants and can help animals to feel protected.
If you want to add duckweed to your aquarium, it is will not require any special conditions to grow. It adapts well to different amounts of light and can help to keep jumping fish or other aquatic animals from escaping your tank.
Will Duckweed Kill My Fish?
If your fish are not eating the duckweed in your tank, it can grow so thickly that it reduces the oxygen level and kills the fish. This can be prevented if you have the kind of fish that will feed on and control it.
In addition to the potential to harm some fish, duckweed can push out other aquarium plants especially in nano tanks. It can also be (undetectably) stuck to aquarium plants you introduce to your tank, so isolate new plants for a few days to ensure there is no duckweed growth.
How Do I Get Rid of Duckweed in My Aquarium?
There are several methods of getting rid of duckweed in an aquarium. Some are more effective than others, so you might have to try more than one technique. Several of the suggested methods might not completely eradicate the duckweed but should help to minimize its spread.
Introduce Fish or Other Animals That Feed on Duckweed
Adding larger duckweed-gobbling fish or small aquatic animals to your aquarium can get rid of your duckweed, or at least help to control it. Many types of turtles will feed on it as a part of their diets, and some aquatic snails nibble on it as well.
Regularly Scoop Out the Duckweed
You can clean out your tank by scooping out the duckweed. You will need to take out all aquarium décor, rocks, etc., and thoroughly clean it off. Other plants may have duckweed stuck to them as well. A small amount of duckweed is all it takes to create a big problem.
If you are manually removing duckweed, you will need to check all the nooks and crannies of your tank. Run your finger along the rim, and the inner edges. Tweezers are great for removing small pieces.
Because duckweed spreads so quickly, you want to remove every bit of it from your aquarium.
Create a Stronger Water Current
Duckweed does not like moving water. If you get a filter with a high flow rate this might help to control the growth. Other ways to promote a current in your aquarium are to add water pumps, powerheads, or wavemakers.
Change the Water Temperature
Depending on what lives in your aquarium, you can try keeping the water too warm or cold. Duckweed will not do well in temperatures over 86°F or under 68° degrees Fahrenheit.
Is Duckweed Good for Ponds?
Duckweed growing in a pond can be a food source for a variety of animals. Young mallards eat it, as do Canadian geese and other semi-aquatic fowl. It is also eaten by certain pond snails and turtles. While it is not their primary food source, beavers will also snack on duckweed.
Another benefit is duckweed’s ability to keep the water clean and reduce algae growth. If you decide you want to grow it in your pond, it is easy to start and easy to grow. The more difficult part will be controlling how rapidly it spreads.
Many of the methods for battling duckweed growth in a pond are the same as for an indoor tank. You can regularly rake or scoop out the leaves with a net or introduce fish that feed on it, such as grass carp. Adding a fountain or another source of current can reduce its growth.
Additionally, there are herbicides on the market that can be used to get rid of it. This is a method of last resort, as you can risk harming other plants and animals with the chemicals. Additionally, once the duckweed begins to die it will decay and introduce harmful bacteria to the ecosystem.
If you are trying to keep duckweed out of your pond, be aware that waterfowl sometimes have it stuck to their feathers and feet.
Is Duckweed Harmful to Humans?
Duckweed is usually not harmful to humans. In fact, its high protein content makes it a good food source for humans as well as animals. It also contains potassium, calcium, zinc, and niacin. The Wolffia globosa variety is consumed as a vegetable in some Asian countries.
One variety of duckweed can be harmful to humans if consumed in large amounts. The Lemna genus often contains high percentages of calcium oxalate (depending on the water conditions where it is grown) which can be toxic if too much is eaten.