Rootless Duckweed, lat. Wolffia arrhiza- Wolffia arrhiza distribution
Family: Lemnaceae;
Genus: Wolffia;
Species and synonyms: Rootless Duckweed (Wolffia arrhiza, Rootless Duckweed, Watermeal, Wolffia globosa, Lentille d'eau naine).
GBIF:
Rootless Duckweed (lat. Wolffia arrhiza) is a species of flowering plant from the family Lemnaceae. This is the smallest flowering plant on Earth, widespread around the world and popular in the aquarium hobby as a floating plant and valuable live food.
Distribution. Rootless Duckweed has a cosmopolitan distribution and is found in warm regions around the world: in Europe, Asia, Africa, North and South America, Australia. The plant inhabits stagnant and slow-flowing waters — ponds, lakes, ditches, rice paddies, preferring organically rich waters.
Care requirements. Rootless Duckweed is a very undemanding floating plant. Optimal water parameters: temperature 18–30°C, pH 6.0–8.0, hardness 2–15 dGH. Prefers bright lighting but can also grow in moderate light. CO2 injection is not required. The plant can grow in both fresh and brackish water.
Planting and care. Rootless Duckweed floats on the water surface and does not require planting in the substrate. Under favorable conditions, it reproduces incredibly quickly, doubling its biomass in 2–3 days. It is recommended to regularly remove excess to prevent the plant from covering the entire surface of the aquarium and shading other plants.
Propagation. Rootless Duckweed propagates vegetatively — by budding. Each tiny "leaf" is a stem with a single bud that separates from the mother plant and forms a new colony. Flowering is extremely rare.
Use in the aquarium hobby and beneficial properties. Rootless Duckweed is one of the best live foods for aquarium fish. Due to its high protein content (up to 40% dry weight), it is ideal for feeding herbivorous and omnivorous fish, especially for raising fry. The plant serves as a natural biological filter, actively absorbing nitrogen compounds (ammonia, nitrites, nitrates) from the water, helping to combat excess organic matter. Rootless Duckweed can be easily cultivated either in a separate container with water and fertilizers or directly in the aquarium.