Aquariumbackground plant · easy
Hornwort: height, light, CO₂ & fish that eat it
Ceratophyllum demersum typically grows 2–12 in tall (5–30 cm) and grows in the background of a tank. It's rated for low–high light, and injected CO₂ is not needed. Temperature 39–86°F, pH 6–9.
How tall it grows
Each bar is roughly the water depth a tank leaves above the substrate. The teal band is the plant's reported height range. ✓ fits, trim means it can reach the surface, ✕ means it typically outgrows the water.
Will it fit your tank?
Quick facts
- Grows to
- 2–12 in (5–30 cm)
- Height basis
- Tropica 2-month avg (listed 5-30+); stems up to 80 cm
- Where it goes
- floating, midground, background
- Light
- low–high light
- Injected CO₂
- not needed
- Growth
- fast
- Difficulty
- easy
- Temperature
- 39–86°F
- pH
- 6–9
- Hardness
- 0–30 dGH
- Feeds through
- leaves (water column)
- Also sold as
- Rigid hornwort; coontail; coon's tail
Planting tip: Rootless: let it float or anchor the stem base in the substrate or under a stone.
Fish and Hornwort
Checked with the same rules as our tank builder: plant-eating and digging named in each fish's sources, plus temperature and pH overlap.
Eats it (9)
- Convict CichlidFlagged as eating live plants
- Common PlecoFlagged as eating live plants
- Common / Comet GoldfishFlagged as eating live plants
- Clown LoachIts sources suggest java fern, java moss, anubias instead
- Tinfoil BarbFlagged as eating live plants
- Buenos Aires TetraFlagged as eating live plants
- Kissing GouramiIts sources suggest anubias, java fern instead
- Yoyo LoachIts sources suggest java fern, java moss, anubias instead
- Fancy GoldfishIts sources suggest anubias, java fern instead
May uproot it (6)
Different water (0)
- Every fish shares some temperature and pH range with it.
Fish that leave it alone and share its water (95)
Common questions
How tall does Hornwort grow?
Growers report about 2–12 in (5–30 cm). Basis: Tropica 2-month avg (listed 5-30+); stems up to 80 cm.
How much light does Hornwort need?
It's rated for low–high light. Growers often disagree on light, so this is the full range across our sources.
Does Hornwort need CO₂?
No. Its sources rate its CO₂ need as low, and it grows without injection.
Which fish eat Hornwort?
In our database, Convict Cichlid, Common Pleco, Common / Comet Goldfish, Clown Loach, Tinfoil Barb, Buenos Aires Tetra, Kissing Gourami, Yoyo Loach, Fancy Goldfish are flagged as eating live plants. Tough-leaved anubias usually hold up better.
Gear for Hornwort
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Related guides
Sources
Values come from these pages, in our own words. Where growers disagree, we show the full range. Last reviewed 2026-10-17.
- tropica.com /en/plants/plantdetails/Ceratophyllumdemersum(021APOR)/4434
- aquasabi.com /Ceratophyllum-demersum
- flowgrow.de /db/aquaticplants/ceratophyllum-demersum