Lemna Minor

Type:Floating Plant
Origin:Worldwide Spread
Growth Rate:Fast
Light Demand:Medium to High
CO2 Demand:Low

Lemna Minor is also known as “common duckweed”, “water lens”, “bayroot” or “lesser duckweed” is an aquatic plant species belonging to the Araceae family. This plant exists in the wetlands, slow-moving streams, and freshwater ponds almost all over the world. Therefore, it is not correct to link its natural habitat to a country or region. According to a common theory, the reason it got this name is that the ducks eat it and spread it around the world.

Lemna Minor has oval-shaped leaves with 1-8 mm long and up to 5 mm wide. It has a structure consisting of 1 to 4 leaves with a root. It divides and propagates if the number of leaves increases. Although root length is generally between 1-2 cm, it can rarely reach up to 15 cm depending on environmental conditions. This plant, which contains different shades of green from light green to dark green, has 1 mm diameter flowers and 1 mm long seeds.


Lemna Minor can grow in any tank size, from nano aquariums to large tanks. The ideal water pH balance for this plant is between 6,0-7,5, and the optimum water hardness is between 4-15 dGH. Water hardness is not essential for the growth of duckweed. It can tolerate both soft and hard water. Therefore, according to some resources, the proper hardness range given is 2-30 dGH values. Waters temperatures within a range of 15 to 30°C are suitable for the growth survival. For this plant, exposure to direct sunlight is the best option for its growth. Although it can grow even in low light with full sunlight and sufficient nutrients the growth will be optimum. In the aquarium, full-spectrum lights are the best option for rapid and healthy growth. Carbon dioxide and substrate additions are not necessary for the growth but, additions of nitrogen, phosphorus, and potassium will increase growth and propagation. It should not be forgotten that fast-flowing water should not be avoided in the aquarium because it prefers slow-moving streams in its natural life.

This plant has some positive effects on aquarium life. It purifies the water from toxic substances by acting as a water filter, reduce the growth of algae, provides food for fish such as cichlids, and reduces the evaporation rate at the water surface.


Duckweed is very easy to propagate in an aquarium environment. If the aquarium conditions such as light, water parameters, and temperature are suitable, the plant will reproduce by itself very quickly. The significant point to note here is that this plant, which can reproduce very quickly as the necessary conditions are met, can occupy the water surface and prevent light from reaching the lower parts of the tank. Therefore, if there are other plants in the aquarium. This must be considered before adding Lemna Minor to the aquarium and keeping it under control. Another problem is that rapid and excessive growth causes a plant layer to form on the water surface, which can reduce the amount of dissolved oxygen in the water. If you encounter such a problem, you may need to remove some of the plants from the aquarium or increase the aeration.

Since Lemna Minor is very easy to keep and it can grow even in minimal conditions and can live even in nano aquariums, it is preferable, especially for the beginner aquarists. On the other hand, because of the reasons mentioned above and having positive effects on aquarium life, duckweed is widely preferred by all aquarists. But, its potential to completely cover the water surface should be noted.

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©2018 Neal Kramer

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