ALLELOPATHY: Plant Chemical Warfare

Steve R. WPT

11/30/20234 min read

War in Your Aquarium: Exploring the Intricacies of Plant Allelopathy

If you've ever set up an aquarium, you know that creating a beautiful underwater landscape is just as important as choosing the right fish. While plants can provide a stunning backdrop for your aquatic pets, they can also become a source of tension in your tank. If you found yourself with an aquarium that is overgrown by one species of plant or perhaps maybe this plant does well in one tank but not so in another? You checked your parameters you're dosing you have the best lighting Etc and your plants seem to not want to grow the plants that are taken over seem to be taking advantage of all the things that you provide for the plants but the ones that you want just won't take off if you've ever wondered why that is I may have the answer. That's because of plant allelopathy, a phenomenon that can cause some plant species to release chemicals that inhibit the growth of others.

In the wild, allelopathy is a natural way for plants to compete for resources. But in a confined aquarium, these interactions can become a battleground. So, let's dive in and explore the intricacies of plant allelopathy in fish tanks.

Understanding Allelopathy

At its core, allelopathy is a chemical warfare between plants. Some species release compounds that are toxic or inhibit the growth of other plants, while others are more resistant to these chemicals. This competition for resources is especially important in aquatic ecosystems, where plants must compete for space and light.

The chemicals involved in allelopathy can be produced by the roots, leaves, or flowers of a plant. They can affect the growth, germination, and even the behavior of other plants nearby. In the case of fish tanks, allelopathy can be a significant problem, as it can limit the growth of certain desired plants and disrupt the balance of the aquarium. That's fascinating if you study horticulture, however if it's costing you money or is a source of frustration, some tips can be found here in this article.

Allelopathy "weapons of choice" in Aquarium Plants

When it comes to aquariums, some plant species are more prone to allelopathy than others. For example, the popular Anacharis (Egeria densa) has been known to release allelopathic chemicals that inhibit the growth of other aquatic plants. Other common plants like Amazon Sword (Echinodorus bleheri) and Java Fern (Microsorum pteropus) are more resistant to allelopathic compounds. One of the most interesting aspects of plant allelopathy in fish tanks is how it affects different plant species. For example, a recent study found that the aquatic plant (Ceratophyllum demersum) Hornwort is highly sensitive to allelopathic chemicals, while Java Moss (Taxiphyllum barbieri) is more resistant. I read another study which also included Hornwort, and it stated that Hornwort actually inhibits growth of certain phytoplankton that competes for nutrients in the water column.

Let's take a closer look at some more of the science behind plant allelopathy. As stated, plants produce a wide range of chemicals known as allelochemicals, which have various functions such as warding off predators or attracting pollinators. Some of these allelochemicals can be toxic to other plants. The most well-known example of allelopathy in the aquarium hobby is from the genus Echinodorus, also known as Amazon swords. These plants produce allelochemicals that inhibit the growth of other plants around them, which can lead to a monoculture of only Amazon swords. However, allelopathy is not limited to Amazon swords. Many other plant species also produce allelochemicals that can affect other plants in the aquarium. For example, Anubias plants release allelochemicals that inhibit the growth of algae, but also affect the growth of other plant species. There's a few allelochemicals that inhibit the growth of algae, as soon as I figure it out I will put the ALGAECIDE on the site for purchase LOL. Allelopathy can also be influenced by other factors, including the pH and hardness of the water, the presence of other chemicals in the tank, and the type of substrate used. That's why it's essential to research the specific plants you plan to include in your aquarium and ensure they are compatible.

Preventing Allelopathy in Your Aquarium

So, how can you prevent allelopathy from becoming a problem in your aquarium?The first step is to choose plant species that are known to be compatible with each other. This is where research comes in. Before adding any new plant to your aquarium, make sure to research its compatibility with the existing plants.

You can use activated carbon in your filter to absorb any allelopathic compounds that may be present. Another approach is to include floating plants, which can help reduce the amount of light that reaches the bottom of the tank and limit the growth of some plant species. Additionally, regular water changes can help reduce the buildup of allelopathic chemicals in the tank. Another strategy is to use physical barriers to separate incompatible plants. This can be done by using plant pots or other structures to physically separate the plants. But what if you already have plants that are at war with each other? The best solution is to remove the aggressive plant from the aquarium. If you're attached to the plant, you can try moving it to a different aquarium where it can grow without affecting other plants. It's important to remember that plant allelopathy is a natural phenomenon, and not necessarily a bad thing. In fact, some allelochemicals can have beneficial effects, such as reducing the growth of algae. The key is to find a balance that works for your aquarium. So, what are some plant species that are known to be compatible with each other? Here are some examples: I will list the most common ones that come to my mind:

- Java fern (Microsorum pteropus) and Anubias (Anubias barteri)

- Cryptocoryne wendtii and Amazon swords (Echinodorus spp.)

- Water sprite (Ceratopteris thalictroides) and Java moss (Taxiphyllum barbieri)

By choosing compatible plant species and keeping an eye out for signs of plant allelopathy, you can maintain a healthy and diverse aquatic environment in your aquarium. Remember, a little research and planning can go a long way in preventing plant wars in your aquarium.

plant allelopathy is a natural phenomenon that can cause plant wars in your aquarium. However, with a little bit of research and planning, you can prevent and manage these issues. Don't let the battle for your aquarium discourage you from having a beautiful aquatic environment in your home.