Using leaves from trees for a natural and healthy aquarium - Details, effect, application

Fallen Leaves in the Aquarium: A Natural Enrichment

With the arrival of autumn, it's a good time to consider enriching our aquariums with the beneficial substances found in leaves. Fallen leaves, often perceived as mere garden waste, can actually be a valuable addition to many freshwater aquariums.

Why Use Fallen Leaves?

In many tropical aquatic environments, such as the Amazon rainforest, fallen leaves constitute a significant part of the ecosystem. They create a natural habitat not only for fish but also for invertebrates.

In nature, tannins contained in leaves help protect plants from bacteria, fungi, and other pathogens.

Biological Effects

As leaves decompose, they promote the growth of microorganisms that are essential for a healthy aquarium. These microorganisms serve as a food source for various microfauna and some fish fry. Moreover, the decomposition process releases tannins, which can help lower the pH of the water and inhibit harmful bacteria and fungi. They also reduce the content of heavy metals in the water.

Aesthetic Effects

Leaves that appear to have fallen randomly to the bottom of the aquarium can give it a more authentic and visually appealing look. They create a subdued, natural-looking environment that can enhance the colors of some fish species.

Dosage

It is essential to be cautious, especially when using leaves that you haven't tried before. Softer and already acidic water will be more significantly affected by tannins and humic substances released from the leaves, lowering the pH more dramatically and quickly than in harder, more alkaline water.

It's important to realize that it's not possible to accurately determine water parameters solely based on its color. It needs to be tested. Therefore, always proceed slowly. There's no need to rush. Each aquarium reacts differently to "inputs" such as compounds released by foliage.

Avoid adding too many leaves at once, as excessive decomposition can reduce the amount of oxygen in the water.

Collection

Collect leaves that are brown and dry, but not too brittle. Avoid leaves that show signs of mold or rot. Rinse the leaves thoroughly to remove dirt and debris. Although some sources mention the possibility of boiling leaves, most users do not recommend this.

Adding to the Aquarium

Place the leaves directly on the substrate or in a mesh bag for easy removal.

Choosing Suitable Leaves

Not all leaves are suitable for aquarium use. The best choices are those that decompose slowly and provide a stable release of beneficial tannins. Among the most popular options are:

Indian Almond Leaves (Terminalia catappa)

Indian almond leaves, also known as Catappa, Ketapang, or Indian almond leaves, are valued in aquariums for their wide range of positive effects on the aquatic environment and fish health. They originate from tropical regions of Asia and Australia, where they are traditionally used in folk medicine.

• Description: When added to aquarium water, they release tannins, which have mild antibacterial and antifungal effects. These tannins can slightly lower the pH of the water and mimic the natural, slightly acidic water conditions in which many tropical fish species thrive. As the leaves decompose, they tint the water a light tea color. This environment is native to species from so-called blackwater streams. It is therefore particularly suitable for aquariums with fish from, for example, South America (tetras, dwarf cichlids) and Asia (bettas). Wide, flat, and slowly decomposing leaves can co-create a natural look that complements planted tanks and provides natural shelter for shy or territorial fish.

• Usage: Catappa leaves are available in dried form in specialized aquarium stores. Before placing them in the aquarium, simply rinse them under running water. They usually float for the first few days, so if this bothers you, weigh them down with a stone or decoration. You can also break the leaf in half and use only part of it or crush it into smaller pieces to speed up the decomposition process.

• Dosage: The number of leaves added may vary depending on the desired effect and the size of the aquarium. A starting point could be one leaf per approximately 10 gallons of water and gradually adjust this based on how the water parameters in the tank change.

• Maintenance: Some aquarists use crushed or whole leaves as part of the substrate, where they slowly decompose and contribute to the nutrient cycle of the tank, thereby supporting plant growth. Although Terminalia catappa leaves can be beneficial, it is good to keep maintenance in mind as well. As the leaves decompose, they can create detritus, so it is advisable to replace the leaves regularly. It is important to monitor water parameters, as tannins can affect pH and water hardness. After all, the goal is suitable conditions for specific fish species.

Oak Leaves

• Description: Oak leaves are readily available and suitable for use in aquariums. They decompose at a moderate rate and are excellent for simulating gentle forest streams. During the decomposition process, they cover the bottom, which then resembles a riverbed or forest floor. Oak leaves, similar to Indian almond leaves, release tannins into the water, which can naturally lower pH and soften water. Such water then has antibacterial and antifungal properties. Tannins and the resulting tea-colored water can help reduce stress in shy fish. For some species, the presence of leaves on the bottom can simulate the onset of the rainy season, which is a common trigger for breeding in the wild. As oak leaves decompose, they become microhabitats for beneficial bacteria and small invertebrates, such as infusoria, which are an excellent food source for some fry.

• Usage: Collect leaves in autumn, ideally after the first frost. Choose dry, brown leaves with no signs of mold. Choose leaves that have fallen and rinse them or let them sit in hot water before use (this will also speed up the release of tannins). Rinse thoroughly and allow to drain before placing in the aquarium. It is recommended, especially for sensitive fish species, to add leaves gradually to avoid sudden fluctuations in water parameters and to monitor pH and hardness. It is recommended to start with 2 to 4 medium-sized oak leaves per 10 gallons of water. The amount of tannin can be assessed by the color, where we want to achieve a light tea tinge to the water.

• Maintenance: It is necessary to be careful not to use leaves that have been sprayed with pesticides or other pollutants. Again, detritus can be released during decomposition, so it is necessary to remove excessively decomposed leaves every 4 to 6 weeks to maintain water quality.

Beech Leaves

• Description: Beech leaves decompose more slowly than oak leaves and therefore last longer in the aquarium. Decomposing beech leaves give the aquarium a rustic yet natural look. With their help, you can imitate the bottom of a forest stream or lake bed. Beech leaves also release tannins, but with lower intensity compared to oak leaves. Tannins naturally soften water, lower pH, and the leaves create hiding places for animals. Tannins from beech leaves have mild antibacterial properties that can help eliminate pathogens in the aquarium. The fine structure and intricate network of veins create ideal hiding places for small and shy species. Furthermore, the presence of these leaves can initiate conditions suitable for breeding. As the leaves decompose, they provide food and shelter for beneficial microorganisms and small invertebrates. They are key to a balanced ecosystem and can serve as food for fry.

• Usage: Collecting and preparing beech leaves is simple. Just collect dry, brown leaves with no signs of mold or dirt. Rinse them under running water before placing them in the aquarium. To accelerate the release of tannins, we can scald the leaves with hot water. It is recommended to start with a small number of leaves, for example 2 to 3 leaves per 10 gallons of water. After evaluating changes in water parameters, you can gradually add more.

• Maintenance: With beech leaves, it is also necessary to remove and replace leaves that are already in a higher stage of decomposition.

Magnolia Leaves

Magnolias, native to warm regions of Asia and America, are known for their beautiful flowers. Less known, however, are the beneficial effects of their leaves on the aquatic environment.

• Description: Magnolia leaves are thicker and decompose more slowly. This means they will last longer in the aquarium. They are also suitable for so-called blackwater aquariums. Magnolia leaves release tannins more slowly than some other types of leaves. This is mainly due to their stronger and more resistant structure. These tannins can help soften water and gradually lower pH. The subdued lighting effect, which is typical of released tannins, can significantly reduce stress in fish. Also, magnolia leaves at the bottom of the aquarium can be a trigger for spawning in fish. Visually, magnolia leaves, thanks to their shape and size, are ideal for creating a dramatic scene. The gradual decomposition of leaves will initiate the multiplication of microorganisms and can be an initial source of food for small fry.

• Usage: Choose leaves that you know have not been treated with pesticides. Rinse the leaves thoroughly, and scald them briefly to be sure. They are quite large. It is therefore recommended to place them so that they provide shelter for fish and overall harmonize the arrangement of the tank. Due to the size of the leaves and their effect, it is advisable to start gradually, for example with one large leaf per 5 to 7 gallons of water.

• Maintenance: It is recommended to monitor water parameters and replace leaves. As soon as you see too much decomposition of the leaves, which, however, takes a little longer with magnolias than with the aforementioned Indian almond leaves, oak leaves, and beech leaves. When to change the leaves can also be observed from the decrease in the intensity of the color of the water in the aquarium. As soon as the light tea color begins to disappear, it is a signal that the leaves have begun to decompose and should be replaced.

Conclusion

Fallen leaves, a seemingly ordinary natural material, become a powerful tool in the hands of an aquarist. Not only can they transform an aquarium into a breathtaking underwater world full of muted colors, but above all, they offer fish and shrimp an environment close to their natural habitat. Whether you choose oak, beech, magnolia, or exotic Catappa, with leaves in your aquarium, you bring harmony and balance to your piece of the underwater realm. Don't be afraid to experiment and observe how the inhabitants of your tank react to this gift of nature. With a little care and creativity, you will succeed in creating a fascinating and healthy environment where your fish will feel at home.