Lemna minor

Lemna minor is one of the most widely distributed plants on Earth, found floating in still and slow-moving freshwater on every inhabited continent. Each frond consists of a single flat, oval body 2–5 mm across with a single root hair. Its extraordinary growth rate under good light means it can double its biomass in a matter of days, providing an essentially unlimited live food supply for goldfish, koi, plecos, and many tropical species, while simultaneously stripping nitrate and phosphate from the water.