Water chestnut (Trapa natans) care guide

Group
Plants
Other names
Water caltrop, Water nut, Buffalo nut, Bat nut, Devil pod, Singhara nut, Trapa bispinosa, Trapa bicornis
Family
Lythraceae (loosestrife family)
Origin
Warm-temperate Eurasia and Africa; introduced in eastern North America
Water
freshwater
Maximum size
50 cm
Temperature
10–30°C
pH
6–8
Hardness
3–15 dGH
Care level
intermediate
Lighting
High light (full sun); CO2 not needed
Flow
Still or very slow water

Care

Trapa natans (water chestnut or water caltrop) is a floating annual of shallow, slow fresh water with soft, rich mud. It roots in the mud and sends up a stem up to about 2 m long, topped by a floating rosette up to 50 cm across of diamond-shaped, toothed leaves. It needs water above 22 °C for at least two months a year to grow and fruit. Do not confuse it with the Chinese water chestnut, Eleocharis dulcis. It is a pond plant rather than an aquarium plant: grow it in a sunny pond or large tub with a muddy bottom. Each fruit is a hard nut with two to four barbed spines about 12 mm long that can pierce thin soles, so take care where nuts may fall. Raw fruit can carry a parasite, so never eat them uncooked. Water figures are our estimate, not from the sources. It is invasive from Vermont to Virginia in the USA, forming dense mats that block light and use up oxygen, and is a listed noxious weed in several US states. Never release this plant or dispose of it in drains or waterways; it is invasive in some countries. Sources: Wikipedia (en.wikipedia.org/wiki/Trapanatans); Wikipedia, List of freshwater aquarium plant species. Checked October 2026.

Breeding

Annual, so it is grown from its large single-seeded nuts each year. Keep ripe nuts cool and wet (never let them dry out) over winter and plant them in mud in spring.

Compatibility and tank mates

Ponds rather than tanks. Its shade suits pond fish in summer, but it can cover the surface and starve submerged plants of light and oxygen. Goldfish and koi may nibble young leaves.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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