Gibbous duckweed (Lemna gibba) care guide

Group
Plants
Other names
Gibbous duckweed, Swollen duckweed, Fat duckweed
Family
Araceae (arum family; formerly Lemnaceae)
Origin
Temperate regions worldwide: Europe (including Britain) to the Himalayas, Africa and the Americas; absent from polar areas and the tropics
Water
freshwater
Maximum size
0.5 cm
Temperature
6–28°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

Gibbous duckweed is a temperate duckweed whose fronds, 3–5 mm across, are often swollen and spongy underneath. It grows on still or slow water and sometimes on mud or damp rocks. It is a standard test species in water-toxicity studies. 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. It is a temperate plant that suits ponds and coldwater tanks well; it will also grow in tropical tanks. Sources: Wikipedia (en.wikipedia.org/wiki/Lemnagibba); 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. It flowers occasionally in shallow, sunny water.

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.

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