Water lettuce
Pistia stratiotes
Also known asNile cabbage
Water parameters
Light and nutrients
Substrate type: epiphyte. Propagation: daughter plants.
Substrate compatibility
| Substrate | pH effect | Nutrient load |
|---|---|---|
| Wood and rock mounts (Hardscape mount) | varies | none |
| Inert sand (Pool filter sand) | neutral / inert | none |
| Inert gravel (Aquarium gravel) | neutral / inert | none |
| Bare bottom (no substrate) (Bare bottom) | n/a | none |
| Aquasoil (ADA Amazonia) | lowers pH | very high |
| Mineralized clay substrate (Seachem Fluorite) | neutral / inert | moderate |
With fish
Origin and habitat
Native to tropical and subtropical regions; the exact origin is debated (possibly Africa or South America). The species (Pistia stratiotes) is a floating plant with rosettes of thick, pale green, velvety leaves (5–15 cm long) that sit on the water surface. The leaves have a spongy, corrugated texture with prominent veins. Long, feathery roots (up to 30 cm) hang below the surface. Water lettuce forms dense floating mats that provide shade, cover, and nutrient export. The species is a serious invasive weed in tropical and subtropical waterways worldwide, forming impenetrable floating mats that block light, reduce oxygen, and displace native vegetation. Regulated as a noxious weed in several US states and Australian states.
Outdoor pond use
- USDA zones
- 8–13 (winter low around -12°C or warmer)
Care notes
Easy floating plant for open-top tanks or outdoor ponds in warm climates. Strong light produces the best growth and largest rosettes; under low light, the rosettes stay small and may deteriorate. Does not thrive under standard aquarium hoods or closed lids; prefers the higher light and air circulation of an open-top setup. Condensation dripping from a closed lid damages the velvety leaves. Temperature: 20–30°C (cold-sensitive; dies below about 15°C). Absorbs nutrients aggressively from the water column through the extensive root system, making it effective for nitrate and phosphate reduction. The trailing roots provide excellent shelter for fry and shrimp. Thin regularly to prevent complete surface coverage. Propagation by daughter plants on short stolons; growth is moderate to fast under good conditions. Check local regulations before acquiring; water lettuce is prohibited in several US states (including Florida and Texas) and in Australia. Where legal, it's an attractive and functional floating plant. In the aquarium, water lettuce is best suited to open-top tanks or ponds where it receives adequate light and air circulation. In outdoor ponds in warm climates (USDA zones 9+), it grows vigorously during summer and can be composted as nutrient-rich biomass. Propagation is automatic via stolons. A single rosette can produce dozens of offspring in a growing season.