Giant duckweed: a purifying floating plant and natural shade provider
For a surface that filters the light, a duckweed that stands out
Giant duckweed (Spirodela polyrhiza) is a rare and attractive floating plant, larger and easier to control than common duckweed (Lemna minor). It quickly forms a plant carpet on the surface, limiting algae growth by absorbing nitrates and phosphates. It also creates shade, reduces evaporation, and provides shelter for microfauna and fry.
Its size (3 to 10 mm per leaf) makes it less easy for goldfish to eat (except the largest ones), but carp enjoy it.
Why introduce giant duckweed into an aquarium or pond?
- Absorbs nitrates and phosphates → naturally combats algae and purifies the water
- Provides shelter for microfauna among its short roots: fry hide there and find living infusoria
- Easy to control: larger leaves are therefore easier to remove than common duckweed
- Compatible with ponds, low-tech outdoor tubs, and low-tech aquariums
- Limits evaporation outdoors and helps preserve a little coolness during heatwaves through the shade it provides
Cultivation and care tips
- 🌿 Floating plant: no substrate or fertilizer needed; it feeds exclusively from the water
- 💨 CO2 is completely unnecessary, since it takes it from the air rather than the water
- ❄️ Cold-tolerant: it can overwinter outdoors because it produces dormant forms (set aside a few plants to restart growth earlier in spring)
- 🌞 Adapts to both direct and filtered light
- ✂️ Regularly remove excess plants to let light reach submerged plants
- 🐟 Compatible with fish, snails (bladder snails, for example), daphnia, water lice, and aquatic microfauna
FAQ - Giant duckweed
Will this duckweed take over everything?
It often spreads quickly, but its larger leaves are much easier to remove by hand.
Can it be placed in a small aquarium?
Yes, it adapts well to nano tanks, provided its growth is regulated. Keep only a few plants to achieve light, irregular shading.
Is it compatible with goldfish?
Yes, they will eat little of it (except the largest ones!). Larger carp, however, enjoy it greatly.
Does it really protect fry?
Yes, its 2 cm roots in clusters and its leaves provide reassuring shelter for young fish. Above all, they find living infusoria there.
Is it a true filtering plant?
Yes, it absorbs excess nitrates and phosphates, contributing to the biological balance of the water. Purification is a more accurate term than filtration.
Additional information
Scientific name: Spirodela polyrhiza
Plant type: purifying and light-filtering floating plant
Packaging: pack of 30 plants (indicative weight: 5 g)
Guarantee: plants grown without any artificial inputs. No fertilizer, algaecide, or antibiotic.
