Duckweed the good the bad and the ugly

Duckweed (Lemna minor) is a floating aquatic plant that is often used in aquariums for various purposes. While it has some benefits, it also comes with certain liabilities. Here are the advantages and disadvantages of using duckweed in an aquarium.

Benefits

1. As a food

   Duckweed is a superfood in every definition of the word; totally undervalued as a food source and an aquarium asset.  Nutrient rich, high protein, self-propagating at an alarming rate duckweed is the definition of the perfect plant.  Babies nibble on the roots providing a 100% full time supplemental food supply.

2. Nutrient Absorption

   Duckweed is known for its ability to absorb excess nutrients, including nitrates and phosphates, from the water. This can contribute to improved water quality by reducing nutrient levels that can lead to algae growth.

3. Oxygenation

   Like other aquatic plants, duckweed undergoes photosynthesis, releasing oxygen into the water. This can contribute to better oxygenation in the aquarium, benefiting fish like guppies.

4. Natural Cover

   Duckweed provides natural cover at the water's surface, offering a shaded area for fish, including guppies. This can be particularly beneficial for aquariums with species that appreciate shaded or dimly lit areas.

5. Algae Prevention

   By blocking some of the light reaching the water's surface, duckweed can help prevent excessive algae growth. This shading effect can create a more balanced environment in the aquarium.

6. Reproduction and Propagation

   Duckweed reproduces rapidly, and a small amount can quickly cover the water surface. This can be advantageous for aquariums with fry (baby fish), as the dense cover can provide protection from larger fish and predators.

Liabilities

1. Excessive Growth

   Duckweed has a reputation for its rapid and sometimes uncontrollable growth. If not managed properly, it can cover the entire water surface, blocking light and potentially impeding gas exchange. Regular removal or thinning may be necessary.

2. Nutrient Export

   While duckweed absorbs excess nutrients, it can also export them out of the aquarium when removed. If your goal is to maintain a planted aquarium with specific nutrient levels, the constant removal of duckweed may affect nutrient balance.

3. Clogging Filtration and Aeration

   The dense growth of duckweed can clog filters and aeration devices. It may require additional maintenance to ensure that water circulation and aeration are not impeded.

4. Limited Aesthetic Appeal

   Some aquarists find duckweed to be aesthetically unappealing due to its small size and rapid growth. It can give the water surface a cluttered appearance.

5. Difficulty in Eradication

   Once duckweed is introduced into an aquarium, it can be challenging to completely eradicate. Even small fragments left behind can lead to its resurgence.

Conclusion

While duckweed offers certain benefits in terms of nutrient absorption, oxygenation, and natural cover, its rapid growth and potential drawbacks, such as clogging and aesthetic concerns, should be carefully considered. Whether to use duckweed in an aquarium with your fish depends on the specific goals of the aquarist and the overall design and maintenance plan for the tank. If used, regular monitoring and management are key to ensuring its controlled presence in the aquarium.