Water Lettuce

Pistia stratiotes

A floating rosette that really does look like a small head of lettuce, with a long beard of roots beneath. It shades the tank, takes nutrients straight from the water and grows fast enough to need weekly thinning.

Light: medium–high
Difficulty: medium
Temperature: 15 – 35 °C (59 – 95 °F)

Plant type: rosette
Growth rate: fast
Tolerates light: medium – high
Carbonate hardness: 0 – 14 °dKH
Propagation: runners
Grows emersed: yes

Appearance

Velvety, ribbed leaves stand in a rosette on the surface; a dense curtain of roots hangs below, sometimes far down into the tank.

Keeping

Simple in an open tank and awkward in a closed one: the leaves rot from condensation dripping on them, and they need space above the water. Bright light and warmth make it multiply quickly, so a share of it goes in the bin every week. In some countries it is treated as an invasive weed and its sale is restricted.

Placement

On the surface, better penned into one part of the tank. The roots are a favourite refuge for shrimp and surface fish, and the shade below suits plants that dislike strong light.

Propagation

By itself: daughter rosettes grow on short runners and separate on their own.

Water conditions match

The water suits 1042 of 1249 species in the catalogue — these are the ones people look up most often.

Swordtail Guppies Cobra Guppy Blood Red Molly Butterflyfish Red Zebra Cichlid Julii Corydoras Featherfin Synodontis Red-finned Parotocinclus Gastromyzon monticola Egg-shaped Goldfish Flame Tetra Gardner's Killifish African Tetra Kenyi Cichlid Cuckoo Catfish Golden Swordtail Hypsolebias picturatus Common Zacco Labeo Bicolor Gambusia Flying barb Gastromyzon scitulus Albino Zebra Danio Geophagus Brokopondo

Will eat this plant

These species damage plants, especially when their diet is short of vegetable food.

Bengal Loach Zebra Loach Burmese Border Loach Emperor Botia Spined Loach Marbled Headstander Pellegrin's Leporinus Leporinus striatus False Black Tetra Common Metynnis Mylossoma duriventre Red Whiptail Catfish Molly sphenops Balloon Molly Lyretail Molly Marble Molly Hi-Fin Platy Hawaii Platy Blue Platy Pintail Platy Black Platy Chocolate Molly Moonlight Gourami Melanotaenia parva

Matching water does not mean the fish will leave the plant alone.

Scientific and other names, conservation status

Other scientific names: Apiospermum obcordatum, Limnonesis commutata, Limnonesis friedrichsthaliana, Pistia aegyptiaca, Pistia aethiopica, Pistia africana, Pistia amazonica, Pistia brasiliensis, Pistia commutata, Pistia crispata, Pistia cumingii, Pistia gardneri, Pistia horkeliana, Pistia leprieuri, Pistia linguiformis, Pistia minor, Pistia natalensis, Pistia obcordata, Pistia occidentalis, Pistia schleideniana, Pistia spathulata, Pistia stratiotes cuneata, Pistia stratiotes linguiformis, Pistia stratiotes obcordata, Pistia stratiotes spathulata, Pistia texensis, Pistia turpini, Pistia turpinii, Pistia weigeltiana, Zala asiatica
Pistia stratiotes: L.
Family: Araceae
Conservation status: LC