Hornwort Care, Planting & Growth in the Aquariums

If you want an easy and fast-growing plant for your freshwater aquarium, hornwort will be your ideal choice. The hardy plant can withstand a wide range of conditions and so proves to be perfect for beginners.

You can also use it as an immersed or floating plant. Thus, it serves a variety of aquarium and aquascaping styles.

What is Hornwort?

Hornwort is a freshwater aquarium plant that grows very fast and is a perfect plant for aquariums.

OriginWorldwide, except Antarctica
Scientific NameCeratophyllum demersum
Common NamesHornwort, Rigid hornwort, Coontail, Coon’s tail
AppearanceMulti-stemmed, several whorls of needle-like green leaves, rhizomes, no roots
SizeUp to 10 ft
Growth RateFast
Care LevelEasy
Minimum Tank Size15 gallons
Water Temperature59-86 °F (15-30 °C)
pH Level6-7.5
Water Hardness5-15 dGH
CO2Not needed
PropagationVegetative fragmentation, bud/side shoot

Where is Hornwort found?

Hornwort is endemic to the North American slow-flowing warm freshwater habitats. However, it’s found in freshwater lakes and ponds all over the world except Antarctica.

This plant is declared a weed in Tasmania, Australia and labeled as an unwanted organism in New Zealand – where it interfered with hydroelectric power plants.

According to the 2018 assessment of The IUCN Red List of Threatened Species, it’s labeled as Least Concern.

Which family does Hornwort belong to?

This plant belongs to the Ceratophyllaceae family under the Ceratophyllales order. While its binomial name is Ceratophyllum demersum, it’s commonly known as hornwort, rigid hornwort, coontail, or coon’s tail.

Interesting Fact: Hornwort is used as a model for plant physiology studies.

How does Hornwort look?

Hornwort leaves closeup

Hornwort is a multiple-stemmed plant that makes a single unit look like several plants. It’s usually dark green, but in warm environments, it’s light green to yellowish.

Small, evenly spaced needle-like filamentous leaves grow from the tall stems. The leaves feel soft, and the stem (along with the leaves) looks like a cat’s tail. Leaves form 6-12 whorls and fork 1-2 times.

The plant doesn’t have true roots. Its rhizoids and some base leaves help it anchor down.

It produces brown male and female flowers – thus a monoecious plant. The flower produces a nut-like ovoid fruit with 3 spines.

This plant stays completely submerged in water, but you can float it on the surface as well.

How big does Hornwort grow?

In the wild, hornwort is known to grow up to 3 m (10 feet) long and 2-2.5 mm (1/10 inch) in diameter. The leaves are up to 2.5 cm (1 inch) long. Its flowers are around 2-2.5 mm (1/10 inch) and nuts are 5 mm (1/5 inch) long.

In the aquarium, without proper care, the plant grows out of the tank or overrun it.

What is the Growth Rate of Hornwort?

The plant has a fast growth rate. However, it’s not measurable as the rate depends on various factors. On average, you may see it grow up to 1-5+ inches in a week.

What are the Benefits & Uses of Hornwort?

Hornwort is popular in the aquarium industry for the following reasons:

1. Aesthetic

Whether you place the plant at the bottom or top, it creates a unique look while swaying in the current. It’s best for jungle aquascaping.

2. Oxygenation

The fast-growing plant undergoes photosynthesis, absorbs CO2, and releases a large volume of oxygen in the water.

3. Improved Water Quality

It also absorbs fish and invertebrate wastes (phosphates and nitrogenous compounds like ammonia and nitrates), maintains the water quality, and reduces the load on filters.

4. Shelter

The bushy tail-like plant is a great spot to hide for fish and invertebrates when scared or in need of shelter from light. It’s also a nursery for fry and larvae.

5. Allelopathic Abilities

It produces chemicals that discourage the growth of other plant species to save nutrients and space for itself. This ability also inhibits stubborn and fast-growing blue-green algae and phytoplankton.

6. Foraging Spot & Food

It’s a spot for biofilm formation, which is a staple diet for shrimplets and newly hatched fry. The plant also sheds leaves, which are food for scavenging species.

How to take care of Hornwort?

Hornwort planted in aquarium

If you have made up your mind to add a hornwort to your aquarium, here are some basic steps to care for this plant.

What are the Tank Requirements for Hornwort?

What is the Tank Size required for Hornwort?

Hornwort must be kept in a minimum of 15 gallons tank. If possible, always go for bigger tanks. In my experience, if planted in nano tanks, you’ll be exhausted from constant pruning.

What type of Water Chemistry is required for Hornwort?

While the hornwort plant is durable and adaptable, the required water parameters will make your journey with this plant even better. So, follow these:

  • pH Levels:
    • Usual: 6-7.5
    • Maximum Tolerance: Up to 10
  • Water Temperature:
    • Withstands: 59-86 °F (15-30 °C)
    • Most Optimal: 75-79 °F (24-26 °C)
  • Water Hardness: 5-15 dGH

Which type of Soil and Substrate is needed for Hornwort?

There’s no specific need for a substrate for this plant. So, you may decide based on the aquatic animals in your tank. However, never bury your plant base or stems in the substrate, or it’ll rot away.

What Lighting & Duration are needed for Hornwort?

The plant can survive on moderate to slightly strong lighting. It can also withstand low light conditions. However, excess low light may cause browning and kill the plant. On the other hand, avoid too strong lighting as well.

The best option is to use LED lighting for 10-12 hours a day.

What is the Water Flow Rate needed for Hornwort?

It prefers moderate and gentle water flow rates. Stagnant water is not suitable for it, and a high flow rate may break the leaves.

How much CO2 is required in the tank for Hornwort?

Due to the rapid growth of the plant, there’s no need for CO2 injection in its tank.

What types of Fertilizers & Nutrition are required by Hornwort?

The fast-growing plant absorbs nutrition pretty fast from its environment. To replenish the lost nutrients from the tank, doze the tank with fertilizers weekly.

What are the Compatible Plants for Hornwort?

As mentioned before, hornwort has allelopathic abilities. It outcompetes all other plants with its high rate of devouring nutrients. When used as a floating plant, it may also block lighting for the remaining plants.

The only plants that can grow in the same tank as this are:

Which Plants to Avoid with Hornwort?

Avoid plants with faster rates of nutrition consumption, like duckweed and pennywort.

Which Aquatic Species are compatible with Hornwort?

The plant is compatible with several fish species like:

  • Betta
  • Molly
  • Platy
  • Guppy
  • Tetra
  • Zebra danio
  • Bristlenose pleco
  • Endler’s livebearer

Some of the best invertebrates that go with it are:

  • Nerite snail
  • Mystery snail
  • Japanese trapdoor snail
  • Ramshorn snail
  • Malaysian trumpet snail
  • Neocaridina sp. shrimp
    • Red cherry shrimp
    • Rill shrimp
    • Snowball shrimp
    • Green jade shrimp
    • Black rose shrimp
    • Blue velvet shrimp
    • Orange sakura shrimp
  • Caridina sp. shrimp
    • Crystal red shrimp
    • Blue tiger shrimp
  • Amano shrimp
  • Ghost shrimp
  • Bamboo shrimp
  • Vampire shrimp

Which Aquatic Species to Avoid with Hornwort?

Hornwort isn’t nibbled on by fish and inverts – probably due to the serrated hard texture or poor taste. However, some aggressive species may cause ruckus and lead to severe shedding in your plants. So, avoid fish that damage the plant:

  • All sorts of African cichlid
  • Goldfish
  • Oscar
  • Gourami
  • Angelfish

Author’s Note: Don’t use aquarium salt in a tank with hornwort. Otherwise, your plant will lose all leaves.

Common Issues & Solutions

While hornwort is one of the easy-to-care-for plants, it’s packed with its own set of problems, like:

Leaf Browning

The tip of the plant turns bronze, copper, or brown due to excess light.


  • Reduce the light intensity.
  • Trim the affected leaves.
  • Ensure water temperature is below 86 °F (30 °C).

Yellow Leaves

This happens due to soluble iron deficiency and lack of light.


  • Dose it with iron-based fertilizer.
  • Ensure the plant gets enough light of proper intensity and duration.


The leaves shed the most after the first introduction to the tank. Shedding stops once the plant gets acclimated to the tank.


  • Wait until the plant gets acclimated to the tank.
  • If it sheds for too long, add nutrients (through fertilizers) or reduce lighting intensity.

Brittle Leaves

The leaves are pretty brittle and break apart under pressure, especially during maintenance.


Be gentle while handling to minimize breakage.


Fast growth is a common issue in this species.


Regularly trim stems to prevent this.

Planting, Growing, Propagating & Pruning Hornwort in the Aquarium

Once you get the hornwort, you have to follow a systematic routine to plant it successfully and maintain it. To know more, keep reading.

How to plant Hornwort in an aquarium?

Some say that planting a hornwort is as simple as throwing it into the tank. However, there are a whole lot of steps necessary. So, let’s know it all!

Safe Introduction

Before introducing this plant to your tank, thoroughly clean the plant to get rid of dirt, debris, and contaminants. Otherwise, your tank water may get polluted.

To clean, follow these steps:

  • Wear gloves, mix 1 part 5% bleach and 19 parts water or 2 tablespoons (30 ml) of bleach for a bit over a gallon of water.
  • Dip the plant for 20 seconds.
  • Thoroughly wash your plant using a dechlorinator solution (water of the same volume and 5 times the recommended aquarium dechlorinator).
  • Soak for 5-10 minutes.

Note: Don’t use peroxide to clean this plant as it’s sensitive to it. It’ll survive but shed all the leaves.

After that, trim discolored plant sections and quarantine the plant for a while.

Tank Placement

It is mostly used as a background plant due to its rapid growth and huge size. In large tanks, you may also use it as a midground plant.

If your fish and invertebrates like floating plants, you can also use it as one.


Let it float if you want to use it as a floating plant and create a shaded tank. For this, you only need to drop the plant in the water. This is the preferred method, as it’s tough to weigh it down. However, don’t let it outgrow, or it’ll block the light from the tank.

If you want it anchored on the ground, don’t bury the base of the plant. Otherwise, it’ll rot away. Instead, wrap a pond plant anchor or tie it using thread or fishing line on the décor.

How to Propagate Hornwort in an aquarium?

This plant is quite easily propagated through vegetative fragmentation. For this, you need to stop trimming for a few weeks. Cut a part of the stem from the mother plant.

Plant it in the substrate or let it float in a low-to-moderate flow region. After a few weeks, it starts growing into the daughter plant.

In nature, during autumn, the plant produces buds or side shoots that sink to the bottom levels of water. During spring, the bud produces new plants. If you have the plant in a pond or large tank, propagation might happen naturally.

How to Prune Hornwort from an aquarium?

Using a pair of sharp trimming scissors, prune the overgrown stems and dispose of them. Otherwise, the cut pieces may grow into new plants.

How to buy Hornwort?

Good signs of health in hornwort plants are:

  • Stem covered in a thick layer of bushy leaves
  • Thin and stiff leaves
  • The older leaves at the base of stems must be deep green
  • Newer leaves on the tips must be lighter green
  • Long branches and side stems
  • No brown patches on the plant

While the price depends on the stores and the locality, on average, this plant is available for $5-10 for a bunch (in 2024).

Note: Unethical sellers sell wild hornwort from lakes and ponds that can’t adapt to the captivity environment. So, choose a reputable seller for this plant.

A word from FishInAquarium

Hornwort is not only low-maintenance but also easy to propagate. It’s also great to fill your tank with greenery with a handful of this fluffy and voluminous plant.

With that said, if you found this article helpful, share it with other enthusiasts. Have a gala time learning to grow this plant together!

If there are any questions, drop us an email, and our team will be in touch with you!

Minnie B Miller - Professional aquarist and owner of FishInAquarium

About Minnie B Miller

Minnie B. Miller, a professional aquarist and owner of FishInAquarium, has over 8 years of expertise in fish breeding and care, gained through her roles at AquaticTX and Sea Lion Landing. Having honed her skills with various aquatic species, she is dedicated to empowering fellow enthusiasts by sharing her knowledge and experience.