Limnobium laevigatum

Amazon Frogbit

Scientific Classification

Kingdom:

Plantae

Phylum:

Tracheophytes

Class:

Liliopsida

Order:

Alismatales

Family:

Hydrocharitaceae

Genus:

Limnobium

Species:

laevigatum

IUCN Status:

Least Concern

Quick Stats

Difficulty:

Easy

Environment:

Freshwater

Temperature:

20-28°C

pH Level:

6 - 8

Water Hardness:

36 - 215 ppm

Growth:

Very Fast

Lighting:

Medium - High

Max Height:

10-40cm

Placement:

Floating

CO2 Requirements:

None

Water Flow:

Low Flow

Aquarium Building Information

Max Height:

10-40 cm

Placement:

Floating

Lighting:

Medium - High

Growth:

Very Fast

CO2 Requirements:

None

Water Flow:

Low Flow

Attachment Method:

floating

Oxygen Production:

High

Waste reduction:

High

About This Species

Basic Description

Amazon Frogbit is a popular floating plant known for its rapid growth, easy care, and an excellent ability to improve water quality in freshwater aquariums. Ideal for beginners, this plant floats on the water's surface, with its roots dangling below, making it incredibly simple to add to any tank without needing special soil or substrate. It acts as a natural filter, absorbing excess nutrients and fish waste from the water, which helps to keep the aquarium clean and reduce the growth of unwanted algae. Its broad leaves create shade, offering a comfortable, low-light environment for shy fish and a perfect hiding place for fry and small shrimp among its long, trailing roots. This hardy plant thrives in a wide range of conditions and does not require CO₂ injection to grow well. It prefers calm water, so it is best to keep it away from the strong output of filters. Due to its fast growth, you will need to thin it out occasionally to ensure enough light reaches the plants and fish below.

Detailed Description

Amazon Frogbit is a highly sought-after floating plant, valued by aquarists for its aesthetic appeal and significant utilitarian benefits in freshwater systems. Originating from the slow-moving waters of South America, it is exceptionally well-suited for the aquarium environment. Its primary biological function is its remarkable capacity for nutrient absorption. The plant exhibits an extremely fast growth rate, fueled by the uptake of nitrogenous compounds like nitrates and phosphates directly from the water column. This process serves as a powerful form of natural filtration, effectively reducing the bioload and out-competing algae for resources, thus helping to maintain clear water and a stable ecosystem.

The plant's structure consists of a rosette of smooth, rounded leaves that float on the surface, while a network of long, feathery roots hangs beneath. These roots are not only efficient at absorbing nutrients but also provide a dense, complex habitat perfect for harboring infusoria, which serves as a first food for newly hatched fish fry. Shrimp and timid fish species also utilize the root system for shelter and foraging. For optimal health, Amazon Frogbit requires adequate illumination, performing best under moderate to high lighting conditions, which stimulates more compact and vigorous growth. A key care requirement is maintaining low surface agitation. Strong water flow can submerge the leaves, leading to rot and decay. Therefore, placement away from filter outflows or the use of floating rings is recommended. While it is very adaptable to a wide range of water hardness and pH levels and does not need supplemental CO₂, its growth can be so prolific that it requires regular culling to prevent it from completely shading out submerged plants and impeding gas exchange at the water's surface.

Scientific Description

Limnobium laevigatum, a member of the family Hydrocharitaceae, is a free-floating perennial monocotyledonous aquatic plant native to freshwater habitats in Central and South America. Its morphology is well-adapted for a floating life. The plant forms rosettes of orbicular to ovate leaves, with the adaxial (upper) surface being smooth and hydrophobic, while the abaxial (lower) surface features a spongy aerenchyma tissue that provides buoyancy. L. laevigatum exhibits two distinct growth forms: an immature stage with small, flat-lying leaves, and a mature stage with larger, more robust leaves that emerge further from the water. Its root system is adventitious, consisting of fine, unbranched filaments that hang freely in the water column, maximizing surface area for direct nutrient absorption. Ecologically, it is a primary producer that forms dense mats in still or slow-moving lentic environments such as lakes, ponds, and canals. These mats significantly alter the underwater light environment and provide a complex physical structure for invertebrates and small vertebrates. Its IUCN Red List status as 'Least Concern' reflects its widespread distribution and abundance. Physiologically, its rapid growth is driven by its high capacity for phytoremediation, efficiently sequestering excess nutrients. The species primarily propagates asexually through the formation of stolons, which give rise to new daughter plants. Sexual reproduction can occur via the production of small, inconspicuous flowers, but this is less common, especially in aquarium conditions. Its strict intolerance to salinity confines it to freshwater ecosystems.

Reproduction Description

Propagating Amazon Frogbit is considered exceptionally easy and typically occurs naturally without any dedicated effort from the aquarist. The species' primary method of reproduction is asexual, carried out through the production of horizontal stems called runners or stolons. These runners extend from the parent plant across the water's surface, and at their ends, new daughter plants begin to form. While the plant can technically reproduce sexually by flowering, this is a rare event in an aquarium and is not a practical method for hobbyists. To propagate the plant, the main technique is simple division. As new plantlets develop on the runners, they will grow their own leaves and root systems. Environmental factors that encourage prolific propagation include moderate to high lighting and a nutrient-rich water column, as the plant's fast growth is directly tied to the availability of nitrates and other minerals from fish waste or liquid fertilizers. A calm water surface is also beneficial, as it allows the new, delicate plantlets to establish without being submerged. To create new independent plants, you can either allow the daughter plant to detach naturally or you can manually snip the runner once the plantlet appears self-sufficient with several leaves and roots. The newly separated plant requires no special care and can be left to float freely. The primary challenge with this species is managing its growth; regular thinning is essential to prevent it from out-competing other plants for light. Keeping the tops of the leaves dry is crucial to avoid rot, a common issue if they are persistently wet from splashing or high water flow.

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