Limnobium laevigatum
Lily-pad-shaped leaves with long trailing roots, the classic 'shrimp nursery' floater. Larger than Salvinia; covers surface in big circular leaves. Easy to overdo: cover 50% of surface max or it shades out everything below. Pulls nitrate aggressively.
Amazon Frogbit (Limnobium laevigatum) is a floating aquatic plant for the floating of a planted tank. It reaches 3–8 cm under good conditions and grows at a fast rate. Light: low to high. CO₂: none. Target 20–30 °C, pH 6.0–8.0, and 2–20 dGH. Substrate: None, floats on surface, draws nutrients from water column. Propagate via daughter plants on runners.
Care at a glance
Lily-pad-shaped leaves with long trailing roots, the classic 'shrimp nursery' floater. Larger than Salvinia; covers surface in big circular leaves. Easy to overdo: cover 50% of surface max or it shades out everything below. Pulls nitrate aggressively.
By Mike ElmiraUpdated 2 min read
Part of our complete guide to the planted aquarium.
The parameters that decide whether amazon frogbit fits in your tank.
Hydrocharitaceae
Floating
Floating
None, floats on surface, draws nutrients from water column
Daughter plants on runners
Calm sun-warmed waterways of the Amazon basin
Central and South America
Tank-mate safety and the species this one is documented to thrive (or fail) alongside.
Hard-won lessons from the tank.
Pull a 5% nitrate reduction every week just by removing excess frogbit — it's an effective nitrate sink. Keep glass lids dry above it; condensation dripping onto the leaves rots them within days. The long roots (up to 20 cm) become a shrimp and fry sanctuary unmatched by any other floater. Pair with Salvinia for two-tier floating cover.
What can go wrong and how to spot it.
Failure modes, in order of how dramatic the fix is.
Yellow leaves: iron. Crispy brown edges: humidity too low (lid evaporation cooking leaves). Slow growth: low nutrients or too cool.
Frogbit's roots harbour beneficial biofilm that shrimplets and fry graze. Surface leaves can develop spot algae if light is too intense.
The practical routine, read top to bottom.
Water column feeder via the long trailing roots. Iron deficiency shows as yellowing surface leaves — dose iron 2–3× per week. Standard fertiliser otherwise.
Skim every 1–2 weeks to maintain 50% surface coverage maximum. Each plant produces daughter plants on short runners — these can be detached and traded.
Where it comes from, how it behaves, and the variants you'll see at retail.
Where it lived before it came home.
Slow lowland waters across Central and South America. Floating plant that never roots in substrate; grows in lakes, swamps, slow rivers.
All of frogbit's life is essentially emersed — leaves float on the surface with undersides submerged.
Small white three-petalled flowers emersed; doesn't flower in aquariums often.
The named cultivars and the lookalikes worth flagging.
L. laevigatum is the standard. L. spongia (North American frogbit) is a sister species sometimes sold mixed.
Often confused with Salvinia natans (smaller, paired oval leaves with surface hairs) and water lettuce (Pistia stratiotes, much larger and ribbed). Frogbit has distinct lily-pad-shaped round leaves with smooth surfaces.
Direct answers to the questions search engines and AI assistants surface most often about this species.
CO₂ requirement: none. Light requirement: low to high. Under low-tech conditions the plant grows at a fast rate.
Amazon Frogbit (Limnobium laevigatum) needs low to high light. Run a photoperiod of 6–8 hours; longer photoperiods invite algae unless CO₂ and dosing are dialled in.
Position: floating. Substrate: None, floats on surface, draws nutrients from water column It typically reaches 3–8 cm.
Propagation method: Daughter plants on runners. Amazon Frogbit is a floating plant.
Target 20–30 °C, pH 6.0–8.0, and 2–20 dGH. Flow tolerance: still to low.
Difficulty: 1/5. Almost unkillable, a solid first-tank choice.
A planted tank is a system. Pair this plant with one entry from each other pillar to plan the whole scape.
