Ceratophyllum demersum
A rootless stem plant that absorbs nutrients across its whole body. Grows fast in any conditions, the right algae-suppressor for new tank setups. Sheds needles when first introduced (light shock); recovers within two weeks.
Hornwort (Ceratophyllum demersum) is a stem (rootless) aquatic plant for the background or floating of a planted tank. It reaches 30–100 cm under good conditions and grows at a very fast rate. Light: low to high. CO₂: not required. Target 15–28 °C, pH 6.0–8.0, and 5–25 dGH. Substrate: None required (rootless, can float or be weighted into substrate). Propagate via snap and re-plant any segment.
Care at a glance
A rootless stem plant that absorbs nutrients across its whole body. Grows fast in any conditions, the right algae-suppressor for new tank setups. Sheds needles when first introduced (light shock); recovers within two weeks.
Updated 1 min read
Part of our complete guide to the planted aquarium.
Leaves yellowing, pitting, or new growth coming in pale or twisted? Work out what it’s short of in our plant deficiency guide.
The parameters that decide whether hornwort fits in your tank.
Ceratophyllaceae
Stem (rootless)
Background or floating
None required (rootless, can float or be weighted into substrate)
Snap and re-plant any segment
Cosmopolitan
Cosmopolitan
Tank-mate safety and the species this one is documented to thrive (or fail) alongside.
Weighing it against something similar? Compare Hornwort head to head:
Direct answers to the questions search engines and AI assistants surface most often about this species.
CO₂ requirement: not required. Light requirement: low to high. Under stable injected CO₂ the plant grows at a very fast rate.
Hornwort (Ceratophyllum demersum) needs low to high light. Run a photoperiod of 6–8 hours; longer photoperiods invite algae unless CO₂ and dosing are dialled in.
Position: background or floating. Substrate: None required (rootless, can float or be weighted into substrate) It typically reaches 30–100 cm.
Propagation method: Snap and re-plant any segment. Hornwort is a stem (rootless) plant.
Target 15–28 °C, pH 6.0–8.0, and 5–25 dGH. Flow tolerance: low to medium.
Difficulty: 1/5. Almost unkillable, a solid first-tank choice.
A planted tank is a system. Pair this plant with one entry from each other pillar to plan the whole scape.
