We have always talked about plants you can grow either in your garden or indoors. For the most part, these plants grew in soil. But what about if you have a fish tank and you want to grow plants there for landscaping purposes? That’s where the hornwort plant comes in. Not only will it give your fish tank the natural marine look, but it also gives the fish shelter from excessive light and anything that might disturb them like an overcurious cat.
Hornwort is one of those aquatic plants that grow practically on their own without much help from you. Suffice it to say that this plant has spread in every body of freshwater except the frozen arctic. If it can do well in the wild, how hard can it be to grow in the safety of your fish tank? Not hard at all.
Hornwort at a Glance
Of all the freshwater aquatic plants, hornwort (Ceratophyllum demersum) is perhaps the most popular one. With over 300 Ceratophyllum species to choose from, you will undoubtedly find the right species to fit with the type of fish you grow and the design concepts you have in mind. However, we recommend the hornwort, or coontail, as it is known sometimes, for its lush green appearance.
In the wild, hornwort is considered an invasive species. That’s because it’s a hardy plant that can withstand harsh conditions and even poor oxygen in the water. While that’s bad news for environmentalists and marine life officials everywhere, it is good news for anyone looking to grow hornwort at home. It means it is easy to grow even if you know next to nothing about aquatic plants and how to care for them.
From New Zealand where it gets inside the hydraulic power generators to the Amazon river, hornwort claims every freshwater pond, lake, or river as its own territory. Since it doesn’t have roots, it tends to float in the water. However, special leaves will anchor the plant in the water. Each plant has many stems. These stems tend to grow out of control in the wild and reach about 10 inches long. In a limited tank, they would usually grow to 3 feet unless you intervene.
The leaves of the hornwort are more like needles and grow in clusters or whorls of 10 on average. Each needle is about one inch tall and, in the filtered light of the fish tank, they have an astonishing green color. And while there are male and female hornworts, both genders tend to flower. The flowers themselves are lackluster. They are usually brown and about half an inch in diameter. After pollination, the flowers are replaced by a small nut with three spines.
Benefits of Hornwort
Ask anybody who has a fish tank and grows hornwort about that plant and they’d gush about its beauty and the natural look it gives the aquarium. But apart from its landscaping purposes, hornwort has other more practical benefits.
- Improves the oxygen levels in the water to the delight of the fish swimming around. Sometimes you won’t need to use an air pump when your hornwort is growing well.
- Adds more color to the aquarium whether it’s floating at the surface or tethered to the bottom of the tank.
- Creates a more dynamic current in the aquarium which helps distribute oxygen and improves the health of the fish.
- Acts as a natural shelter for fish swimming around. Fish don’t like bright light and if two fish don’t get along in the same aquarium, hornwort offers protection.
- It’s suitable as a nursery for fry just like java moss.
- The fallen leaves and dead flowers serve as an easy source of food for the fish.
- Hornwort also cleanses the water as it feeds on fish droppings and other pollutants in the water.
- In the tank, hornwort inhibits the growth of blue-green algae.
How to Grow Hornwort
With so many benefits and advantages, you can see why this particular hornwort is popular in many aquariums. So when it comes to growing this aquatic plant you need to think of two things. The aquarium and whether to float or plant it.
The Aquarium Conditions
As an aquatic plant, you won’t need to worry about soil or pots. It’s all about the aquarium size and condition. The good news is, you can just about use any tank or aquarium to grow hornwort. It’s a hardy plant that survives in different conditions in the wild. However, you need to have a tank that takes at least 15 gallons before you consider growing hornwort. As mentioned, it grows to a few feet and doesn’t do well in limited spaces.
The water temperature should be between 60 and 85 degrees Fahrenheit. If the temperature drops below that, the plant will struggle to grow and the leaves will turn dark brown. Higher temperature also isn’t ideal for its survival. As for the water pH, make sure it’s not below 6 or above 7.5. Pay attention to any nitrogen pile up in the tank. Higher levels of ammonia, nitrates, or nitrites will suffocate the plant.
For hornwort to produce oxygen and thrive in the tank it needs bright light. You can keep the aquarium near a window that gets plenty of sunlight or you can use fluorescent lights for at least 10 hours a day. The clarity of the tank and water also affects the quality of the light that the plant gets. So make sure the tank walls are clean and the water is clear.
Plant vs. Float
The other pressing matter here is whether you should plant hornwort in the substrate or let it float to the surface. The choice comes down to personal preferences, yours as well as that of the fish. Some fish would like to swim around the stems of hornwort and hide behind them. Others would prefer to have the water space all to themselves in which case you should let hornwort float.
For example, if you have fish like the hatchetfish that spend most of its time near the surface, then floating hornwort not only will give it shelter but also a place to lay its eggs. Meanwhile, fish species such as loaches or tetras prefer an anchored hornwort since they swim near the bottom of the tank for the most part. Either way, make sure the plant is not close to the water filter since it will be covered with a lot of debris.
Once you get your hornwort growing nicely in the aquarium, you won’t have to worry about much. It has enough light, adequate temperature, and the water is clear and filtered. That’s practically all it needs to grow and thrive. However, it just might grow well beyond the size of the tank. In the right conditions, hornwort will grow about 5 inches a week. It’s one of the fastest aquatic plants when it comes to growth rates.
You can even encourage it to grow more by simply giving it more light. But pretty soon, you’ll find that you have a problem on your hands. The hornwort whether it’s floating or anchored is taking up more space in your aquarium. If that’s not what you have in mind, then you’ll need to prune it. Simply trip the top of the stem to the desired length and watch it grow again.
As for nutrition, make sure no other plants are competing with your hornwort for food and nutrients. That can impact its growth. You can use plant nutrient supplements about once a week to help it grow. Also, check the water temperature since any sudden changes will impact the growth of hornwort.
Before you drop a hornwort stem in the aquarium and hope for the best, you need to make sure that your fish can live with it. While the majority of fish species won’t have a problem with a hornwort in the tank, some species don’t tolerate the needle-like leaves floating in the water.
In general, you can grow hornwort in an aquarium that houses guppies and common mollies. They hide in the stems and use them for protection. If you grow angelfish or gouramis, they feed on hornwort leaves which helps with managing the growth of the plant. Just make sure you don’t have too many fish of these species in the tank since they could strip the hornwort stems bare and kill it.
If you have a shedding problem, hornwort sheds a lot which pollutes the water, then consider growing shrimps, snails, or any type of scavenging fish. They feed on the falling leaves and keep the water clean. This helps you with the care and maintenance of both the aquarium and your aquatic hornwort.
As an aquascaping plant, hornwort is one of the least demanding plants you can grow in a fish tank. Its hardiness along with its many benefits make it the ideal candidate that keeps your fish protected, enriches the water with oxygen, and creates a natural marine habitat for fish of all types and species.