Water lettuce

Quick facts

Max height

10 cm

Growth rate

fast

Difficulty

beginner

Placement

floating

Propagation

daughter plants

Water parameters

Temperature

22–30°C

pH

6.0 to 8.0

Hardness

1 to 25 dGH

Light and nutrients

Lighting

medium

CO2

not needed

Substrate

epiphyte

Feeding

feeds from the water column (use liquid fertilizer)

Substrate

What this plant roots into (or attaches to). The substrate affects both plant nutrition and water chemistry; see each linked page for full effects.

This plant feeds primarily from the water column, so substrate choice matters more for its fish-tank compatibility than for plant nutrition.

With fish

Plant-eating fish

will be eaten by mollies, silver dollars, large goldfish, and other plant-grazers

Diggers (corydoras, loaches)

fine - root system or attachment style handles it

Root-disturbing fish

sensitive to root disturbance, plant where roots stay undisturbed

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

This species transitions to outdoor ponds well, not just indoor aquariums.

Outdoor pond zones (USDA)

8 to 13 (winter low around -12°C or warmer)

Below the minimum zone, the plant won't overwinter outdoors but can still be grown seasonally and overwintered indoors. Several pond-friendly species (water hyacinth, water lettuce, parrot's feather) are regulated as noxious in some jurisdictions; check the legality data on the profile before releasing anything to an outdoor body of water.

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.

Further reading

• How to cycle a fish tank
• Water chemistry for fishkeepers: pH, GH, KH, and what they mean