Does Hornwort need CO2?

No. Hornwort grows in low-tech tanks without CO2 injection or liquid carbon supplementation.

What light does Hornwort need?

Hornwort is a low-light plant. Standard aquarium LEDs cover this with room to spare. It is one of the plants you can light from a basic shop hood and still get growth.

Is Hornwort safe for shrimp?

Yes. Hornwort is safe in shrimp tanks. The usual quarantine still applies: any plant from a commercial nursery should be soaked and rinsed first to flush copper and pesticide residue.

Image: Wikimedia Commons — attribution available on this site.

Plant appearance can vary with lighting, nutrients, CO₂, and whether it is grown submerged or emersed.

easylow lightNo CO2fast growthstem

Hornwort

Ceratophyllum demersum

Also: Rigid Hornwort, Coontail

Hornwort is a fast-growing, rootless stem plant that can be floated or anchored in substrate. Highly effective at absorbing nitrates, making it a practical choice for new tanks or overstocked setups. Needle-like leaves shed readily, vacuum them up regularly.

Evidence: verifiedConfidence: high

Care at a glance

Difficultyeasy

Lightlow

CO2Not needed

FertiliserNot essential

Growth ratefast

Max height200cm

Placementbackground

Min tank20L

Water parameters

Temperature15–30°C

pH6–8

Shrimp safeYes

Herbivore risknone

Propagationstem cuttings

Beginner guidance

Can be floated or loosely planted; will shed needles when conditions change. Trims frequently, cut the top growth and replant. Good for cycling tanks due to high nutrient uptake.

Cautions

Needle shedding can clog filters in heavy quantities.

Sources

Ceratophyllum demersum. Wikipedia — Worldwide distribution, growth biology, and use as oxygenating / floating plant.
Ceratophyllum demersum. Flowgrow — Aquarium care notes, light requirements, and nutrient uptake observations.

Fish whose water overlaps

Peaceful freshwater species with overlapping temperature and pH — still run a pair check for the real mix.

Similar plants

Java Mosseasy · low light · no CO2
Anubiaseasy · low light · no CO2
Java Ferneasy · low light · no CO2
Amazon Swordeasy · medium light · no CO2
Water Wisteriaeasy · medium light · no CO2
Water Spriteeasy · medium light · no CO2

Plan the tank around this plant

Set a 20L+ footprint, then verify livestock before you buy Hornwort.

Open pair checker Tank builder

Tank hubs: 30L

Related plant guides

Easy beginner aquarium plantsLow-light aquarium plantsPlants for shrimp tanks

All plants 30L tank hub

Common questions about Hornwort

Does Hornwort need CO2?: No. Hornwort grows in low-tech tanks without CO2 injection or liquid carbon supplementation.
What light does Hornwort need?: Hornwort is a low-light plant. Standard aquarium LEDs cover this with room to spare. It is one of the plants you can light from a basic shop hood and still get growth.
Is Hornwort beginner-friendly?: Hornwort is rated easy for difficulty. Can be floated or loosely planted; will shed needles when conditions change. Trims frequently, cut the top growth and replant. Good for cycling tanks due to high nutrient uptake.
Is Hornwort safe for shrimp?: Yes. Hornwort is safe in shrimp tanks. The usual quarantine still applies: any plant from a commercial nursery should be soaked and rinsed first to flush copper and pesticide residue.