Frogbit (Limnobium laevigatum)

PROHIBITED MATTER: If you see this plant report it to the NSW Invasive Plants & Animals Enquiry Line 1800 680 244



Frogbit is a floating freshwater plant from Central and South America. It has been kept and traded for use in fish ponds, aquariums and water features. It can rapidly invade and smother waterways and is a serious biosecurity threat to NSW. 

Plants can form into large mats of runners and adult plants can develop very quickly. Juvenile plants have a great capacity for distribution in that they are small and can be easily and quickly carried along by water currents.


The first known occurences of frogbit in NSW have been found in a natural waterway in a bushland reserve, and in fish ponds on private property at Green Point, near Forster. It has also been found advertised for sale by online sellers around Sydney. These occurrances are subject to an immediate eradication response. 


Frogbit spreads when plants move in water, but a common cause of spread is the dumping of illegal aquarium or pond plants in waterways. 


Plants float on the water surface, and have smooth, rounded, fleshy green leaves up to 4 cm across, with sponge-like sections on their undersides. 

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If found, frogbit must be reported immediately for positive identification and assistance with control and proper disposal of the plant matter. Check for plants in fish ponds, aquariums, fish tanks, water features, dams and waterways.

Herbicide options

Contact your local council weeds officer for control advice for Frogbit (Limnobium laevigatum).

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Biosecurity duty

The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area Duty
All of NSW General Biosecurity Duty
All plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.
All of NSW Prohibited Matter
A person who deals with prohibited matter or a carrier of prohibited matter is guilty of an offence. A person who becomes aware of or suspects the presence of prohibited matter must immediately notify the Department of Primary Industries
All species of Limnobium are Prohibited Matter

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For technical advice and assistance with identification please contact your local council weeds officer.
For further information call the NSW Invasive Plants and Animals Enquiry Line on 1800 680 244 or send an email to

Reviewed 2017