Instructions
Collect the duckweed from a local body of fresh water, such as a small river, pond or lake. Use a large aquarium net to gather the plant and place the mass in a bucket with some clean, fresh water.
Visit a local fish store to purchase duckweed. Most large businesses will have this ubiquitous plant for sale.
Visit the website for an online aquarium plant retailer. If you cannot find duckweed at a local store, you can order it from Internet retailers.
Attend a local aquarium club's auction. Hobbyists will gather from time to time to sell and bid on fish, plants and aquarium supplies. You are sure to find someone who will sell you duckweed.
How to Get Duckweed
Duckweed is a small flowering plant that floats on the surface of ponds and aquariums. Hobbyists use it to provide shade to their pond fish, to protect against the direct sunlight. Herbivorous fish will also devour duckweed if offered it at mealtime.