TankBud

Amazon frogbit

Limnobium laevigatum

Also known as Frogbit, South American spongeplant, Smooth frogbit, Hydrocharis laevigata

FreshwaterFloatingRunnersPlantletsSide shoots

Invasive. Can be invasive in warm climates and is regulated in some areas. Never release into the wild; dispose of in the trash.

Amazon frogbit (Limnobium laevigatum)
Cardex · Public domain

Care at a glance

Light
Medium light
CO2
No CO₂ needed
Temperature
68–82°F
20–28°C
Max height
2 in
5 cm
Growth rate
Fast
Placement
Floating
Type
Floating
pH
6.0–7.5
Hardness
2–15 dGH
Spread
5.9 in (15 cm)
Nutrient uptake
Water column
Growth region
Submersed or emersed
Difficulty
Beginner
Family
Hydrocharitaceae
Origin
Central and South America

Overview

Amazon frogbit is a fast-growing floating plant for the surface of the tank. It is a beginner plant that spreads quickly.

Did you know

Amazon frogbit soaks up nutrients so well that it is used in wastewater treatment and as a green manure. That same vigor has made it an invasive nuisance in warm regions, so never release it outdoors.

Caring for Amazon frogbit

Set Amazon frogbit on the surface. It needs no substrate and no CO2, and it grows quickly under medium light. Its long roots act as a strong nitrate filter and a refuge for shrimp and fry.

It feeds from the water column, so dose a complete liquid fertilizer. Stunted, pale growth points to a nutrient deficiency or to a lid trapping heat. It grows at 68 to 82°F (20 to 28°C).

Melting or yellowing leaves usually come from condensation, or from hard surface spray hitting the crown. Leave an air gap under the lid and keep the surface flow gentle.

It multiplies fast, and the daughter plants break away to float on their own. Left alone, it will blanket the surface, so thin it regularly to keep light reaching the plants below.

Good to know

Amazon frogbit belongs to the family Hydrocharitaceae, the same family as Vallisneria and Egeria. The undersides of its floating leaves carry a spongy, air-filled tissue called aerenchyma that gives it buoyancy. That tissue is the origin of the alternate name spongeplant. It spreads aggressively by stolons that bud off daughter plants, forming dense connected colonies. It can also flower and set seed.

In the wild

Amazon frogbit is a free-floating plant native to Central and South America, including the Amazon basin. It drifts across still and slow-moving ponds, lakes, marshes and river backwaters. Its rounded, glossy leaves sit on the surface, with a thick mass of long roots trailing below. In bright, open conditions, older plants can lift their leaves off the surface into a low emersed rosette.

Common questions

Does Amazon frogbit need to be planted in the substrate?

No. Amazon frogbit floats at the surface and takes its nutrients straight from the water.

Does Amazon frogbit need CO2?

No. Amazon frogbit grows well without added CO2.

How much light does Amazon frogbit need?

Amazon frogbit wants medium light. A light sold for planted tanks covers it.

How do you propagate Amazon frogbit?

Amazon frogbit propagates by runners, plantlets and side shoots. New plants form along its runners and break away to float on their own. Plantlets bud from the parent and drift off.

Related plants