Common Frogbit

European frogbit looks like a miniature Amazon frogbit with kidney-shaped leaves that sit flat on the water surface and subtle purple undersides. Hydrocharis morsus-ranae is native to temperate Europe and Asia, where it grows in slow-moving ditches and ponds. Each leaf rosette sends out runners just below the surface, and a dense mat can form within weeks during the growing season.

Unlike tropical floating plants, frogbit prefers cool conditions and declines above 26 °C, making it a better fit for unheated or seasonal tanks. In autumn it produces winter buds (turions) that sink to the bottom and sprout again in spring — a useful trait for outdoor ponds. No fertiliser or CO₂ is needed; it draws all its nutrients directly from the water column.

The long, unbranched roots that hang below each rosette provide excellent cover for fry and are a favourite spawning site for egg-scattering fish. In mixed planted tanks, remove excess frogbit weekly to prevent it from blocking light to submerged plants.