Frogbit

Frogbit is a free-floating plant of the Hydrocharis genus, related to the better-known European frogbit but native to a much wider band of Asia from the Russian Far East through China and Japan to tropical Southeast Asia. The round, slightly cupped leaves float on the surface, each with a small notch at the base, and short roots hang below into the water column.

It reproduces by runners that cross the water surface, sending up daughter rosettes every few centimetres, and by division. In an open tank it needs no CO₂ and draws nutrients straight from the water, so it can outgrow a surface quickly when light and nutrients are plentiful. Moderate light and still water keep it healthy; strong surface agitation stresses it.

Because this species has no published cultivation profile in the usual reference databases, the values here are estimates based on the care of related floating plants. It tolerates a broad temperature range of about 18 to 28 °C and neutral to slightly alkaline water. The dangling roots provide shelter for fry and surface-shy fish, but keep the surface partly clear so it does not shade everything below.