Amazon frogbit

Overview

Amazon frogbit (Limnobium laevigatum) is a favourite floating plant — clusters of round, lily-pad-like leaves on the surface, trailing long, feathery roots into the water below that fish and fry love to shelter among. Like all good floaters it grows fast, drinks up excess nutrients, shades the tank and helps hold algae at bay. It is easy to keep and looks wonderfully natural, with the main task being to thin it before it blankets the entire surface.

Planting & placement

There is nothing to plant — Amazon frogbit simply floats on the surface. Drop it in and it drifts, sending its roots down into the water column. Filter flow tends to push floaters into one corner, so many keepers pen it behind a floating ring or a length of airline to keep it tidy and stop it covering the whole tank. Leave open surface for gas exchange and feeding. It needs no substrate and no anchoring; those long roots are a superb fry refuge — see aquascaping for beginners for using floaters in a layout.

Light, CO2 & ferts

Amazon frogbit does best under medium to high light; brighter light gives bigger, greener leaves and faster growth. It needs no CO2, since floating leaves take carbon from the air. As a fast grower it feeds heavily and is an excellent nutrient sponge — a regular water-column fertilizer keeps it green, and its appetite for nitrate is exactly what helps starve algae. See how much light aquarium plants need to gauge your levels.

Propagation & problems

Propagation happens on its own: frogbit sends out runners that produce daughter plants, which detach and spread across the surface, so a few starter plants become a full mat quickly. The common problems are rot and yellowing from wet leaves or a nutrient shortfall, and simply the plant’s own vigour — left unchecked it shades and starves your rooted plants of light. Scoop out handfuls regularly and discard them (never into the wild). Kept fed, dry-leaved and thinned, Amazon frogbit is one of the most attractive and useful floaters you can own.