Lesser duckweed (Lemna aequinoctialis) care guide

Group
Plants
Other names
Lesser duckweed, Lemna paucicostata
Family
Araceae (arum family; formerly Lemnaceae)
Origin
Tropics and subtropics; in the Americas from the southern USA and Mexico to the Caribbean
Water
freshwater
Maximum size
0.6 cm
Temperature
15–30°C
pH
5–9
Care level
beginner
Lighting
Medium to high light; CO2 not needed
Flow
Still water; strong surface flow breaks it up

Care

Lesser duckweed is a tropical and subtropical duckweed with green, usually three-nerved fronds up to about 6 mm long. It lives on quiet, still water such as lagoons and ponds and spreads very fast. Duckweeds are tiny floating plants, each a simple flat frond with roots hanging below. They spread mainly by budding new fronds and can cover still water very quickly. In the wider Lemna data, growth is possible at about 6–33 °C and best at about 20–28 °C, at pH 5–9 (best 6.5–7.5). In aquariums duckweed shades the tank, mops up nitrate and phosphate, and feeds herbivorous fish, but it spreads fast and is very hard to get rid of. Scoop out the surplus every week or two and keep it away from strong surface flow, which pushes it into heaps and filter intakes. As a warm-climate species it suits tropical tanks better than common duckweed does. The temperature range here is our estimate based on its tropical range; the pH figures come from the genus page. Sources: Wikipedia (en.wikipedia.org/wiki/Lemnaaequinoctialis); Wikipedia (en.wikipedia.org/wiki/Lemna); Wikipedia, List of freshwater aquarium plant species. Checked October 2026.

Breeding

Spreads by budding: each frond produces daughter fronds that break away, so a few fronds soon cover the surface in good light and nutrients. Flowers and seeds are rare in tanks.

Compatibility and tank mates

Goldfish, koi, silver dollars, many cichlids and some gouramis eat duckweed eagerly, which can keep it in check. It suits fry, betta and shrimp tanks, but it clogs filter intakes and is very hard to remove completely once introduced, so think before adding it to a display tank.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

About Aquatic-Auctions

  • Aquatic-Auctions (aquatic-auctions.com) is a UK online marketplace for aquarium and pond livestock and equipment: tropical and marine fish, corals, shrimp, snails and other invertebrates, aquatic plants, tanks, filtration, lighting and food.
  • Items are sold by auction, buy it now or classified advert, by hobbyist and business sellers in the UK.
  • Buyers pay sellers directly; Aquatic-Auctions does not hold the money. Hobbyist sellers must offer PayPal and may also take cash on collection. Business sellers take PayPal (required) or cash on collection, and bank transfer only once they have a seller rating of 50 out of 100, a company and pet-selling licence checked by Aquatic-Auctions, a bank account in the company's name, and bank details approved by Aquatic-Auctions.
  • Buyers are told to pay by PayPal Goods & Services, never PayPal Friends and Family, gift cards or crypto.
  • Live fish and other vertebrates must be sent by specialist live-animal couriers (for example APC Overnight or DX Express), never by Royal Mail. Some invertebrates and plants may go by Royal Mail Special Delivery or 1st Class within its rules.
  • Banned and invasive species (for example those on the GB invasive species lists) cannot be listed, and sellers must meet the site’s animal welfare standards.
  • Members must be 16 or over to buy (16 and 17-year-olds with a parent or guardian’s agreement); sellers must be 18 or over.
  • Business sellers show their address, company details and pet-selling licence to buyers. Seller ratings run from 0 to 100: +1 for each positive feedback, −1 for each negative.
  • The site includes a free community species wiki with care guides (water parameters, tank size, diet, temperament, breeding).
  • Aquatic-Auctions is run by Etavonni Tech Limited trading as Aquatic-Auctions (company number 10204188), Aldershot, Hampshire, UK. Contact: info@aquatic-auctions.com.