Duckweed for natural aquariums: an eco-friendly, water-purifying floating plant
What is duckweed?
Duckweed (Lemna minor) is a tiny floating plant that forms a green carpet on the surface. Extremely hardy, it is suitable for filter-free aquariums and all low-tech tanks. Its rapid growth allows it to quickly absorb nitrates and phosphates, making it a valuable natural way to fight algae in aquariums and ponds. Best of all, it is a choice food for goldfish and koi carp.
Benefits of duckweed in a natural aquarium
- Rapid water purification: absorbs nitrates and phosphates, making it an excellent water-purifying aquarium plant
- Natural shade: soothes sensitive fish and shrimp
- Habitat for microfauna: infusoria, springtails, daphnia... and thus provides the live food fry need
- Fresh, natural food: much loved by goldfish, koi carp, and other herbivores
- Very easy floating plant: perfect for ponds, outdoor bin ponds, and low-tech tanks
How do you care for duckweed?
- 🚀 Explosive growth: remove the excess with a net or let goldfish eat it
- 🚫 No substrate needed; roots float freely at the surface
- ☀️ Bright light: the stronger the light, the faster it grows, and the more nitrates and pollutants it absorbs
- 🌡️ Temperature: 1-30°C. Frost will usually kill it, but in winter it sinks to the bottom to avoid freezing until spring
Our tips for using duckweed
Simply place the duckweed on the surface: it cannot be submerged and will float on its own.
Ideal floating plant for:
- 🐠 Community tanks
- 🪣 Outdoor bin ponds
- 🏊 Ponds, especially those with goldfish or carp, which love it (a source of fiber and vitamins)
“Duckweed is the Swiss Army knife of the natural aquarium: it filters, feeds, and protects - an absolute classic!” — Mattier
FAQ - Duckweed for aquariums
Will duckweed take over the aquarium?
Yes, it grows quickly, so you need to remove the excess regularly.
Is it suitable for a filter-free aquarium?
Absolutely. It is a natural way to stabilize water parameters and absorb nitrates in a low-tech tank.
Is it dangerous for fish?
No. On the contrary, some fish eat it. Just keep an eye on its spread to make sure it does not block the light.
Does it need substrate?
None: this is a strictly floating plant.
Does it reduce the light too much for submerged plants?
If the carpet becomes too wide and dense, it is important to remove some of it to let the light through.
