Why Your Anubias Leaves Are Turning Black And How To Fix It!

Anubias, a popular aquatic plant, is well-known for its hardiness and ability to thrive in various aquarium conditions. However, a common issue that many aquarists face is the plant’s leaves turning black. This can lead to the decline of the plant’s overall health and affect its ability to contribute to the stability of the aquarium’s ecosystem.

Several factors can cause the leaves of an anubias plant to turn black, including algae growth, fungal infection, damage, lighting conditions, and nutrient deficiencies. Identifying the underlying cause is critical in addressing the issue and restoring the anubias plant’s health. Prevention strategies, such as proper lighting, pruning, and nutrient supplementation, can help ensure that the leaves remain healthy in the future.

Please note, this article is focused on Anubias plants that are fully submerged in water permanently or for long periods of time. Many of the points raised in the article are still relevant for Anubias plants that are not submerged and can still help treat black leaves on the plant.

Key Takeaways

  • Anubias leaves turning black is a common issue with various potential causes
  • Identifying the cause and addressing it is crucial for restoring the plant’s health
  • Proper care and prevention strategies can help maintain healthy anubias leaves in the long run
An infographic of an Anubias care sheet

Common Causes For Black Anubias Leaves!

There are a number of common causes of black Anubias leaves and in most cases, it is easy to identify the problem that you are having. Once the problem has been correctly identified, you should be able to fix the issue and your Anubias will usually make a full recovery.

Lighting Issues

anubias leaves turning black

Anubias plants can experience black leaves due to inappropriate lighting conditions. Although they can tolerate low light, providing insufficient lighting may cause the leaves to turn black.

Check that your light intensity is low to medium intensity and adjust the lighting duration to approximately 8 hours a day to avoid adverse effects. Some people do recommend longer light intervals but this can also start to encourage algae growth.

If the leaves of your Anubias were turning black due to lighting problems, you will usually see improvements within a week.

Nutrient Deficiency

A lack of essential nutrients can lead to black leaves as well. Make sure the plant has access to necessary nutrients such as nitrogen, phosphorus, and potassium. Insufficient nutrients may slow down the plant growth, resulting in blackening of the leaves.

Monitor the nutrient levels in the tank and consider using fertilizers if needed.

There are some specialist substrates on the market that offer a complete nutritional package for live plants in the tank but they are often over priced. If you do need to suppliment the leaves of your Anubias plant then fertilizers will usually be the better option.

It can take a couple of weeks before you start to see improvements in your Anubias plant if its leaves were turning black due to nutritional issues. Most people should see an improvement within the two to three week point.

Water Parameters

A water test kit for checking the water parameters of your aquarium

Maintaining proper water parameters is crucial for the overall health of Anubias plants. There are a number of water test kits on the market that can help you accurately monitor your tanks water parameters to ensure that they are in range.

Here are the standard water parameters that we recommend for healthy Anubias plants:

  1. Water Temperature: Anubias plants are very adaptable and can survive in a wide range of temperatures, generally between 72-82°F, they can tolerate temperatures outside this range but will have a higher change of developing black or brown leaves.
  2. pH: Anubias plants prefer a pH range from 6.0 to 7.5, although they can adapt to slightly more acidic or basic water conditions.
  3. Water Hardness: Anubias can tolerate a wide range of hardness but typically do well in soft to moderately hard water. A general hardness of 2-15 dGH and a carbon hardness of 3-8 KH is usually recommended.
  4. Water Flow: A low water flow is usually the best option for a healthy growth rater in your Anubias plant but you are able to keep them in tanks with moderate and high water flows if needed.

If any of these parameters are out of range then there is a chance that this may be the cause of the black leaves on your Anubias plant. Depending on the parameter and the amount of time it has been out of range, it may take over a month before you start to see an improvement in your plant.

Slow Growth Rate

Anubias plants are naturally slow-growing. Depending on your tank setup, one new leaf per month can be considered above average results.

However, below optimal conditions can further reduce their growth rate, making them more susceptible to black leaves. Providing the necessary nutrients, light, and maintaining ideal water parameters will help improve their growth rate, reducing the risk of leaf blackening.

Fungal Infection

A fungal infection on substrate

Fungal diseases can be another cause of black leaves in Anubias plants. Here are some common signs of fungal infection to lookout for on your Anubias in addition to the black leaves:

  1. Cottony or Wooly Growth: Fungi often appear as cottony or wooly white patches on the plant. This could be seen on the leaves, stems, or roots.
  2. Discoloration: Fungal infections can lead to discoloration of the plant parts. The leaves might turn yellow or brown and appear ‘melting’ or rotting.
  3. Spots or Lesions: Some fungal infections might cause dark or black spots on the leaves. These lesions could eventually lead to larger patches of damage.
  4. General Decline: Infected plants might exhibit signs of general ill health, such as slow growth, drooping or wilting, and loss of leaves.

If you do notice any of these signs of fungal infection, dose your tank with a suitable anti-fungal treatment as soon as possible. If you have a heavily planted tank, quarantining your Anubias during treatment may be a good idea too.

Damage To The Roots

Damaged roots can lead to black leaves, as they hinder the plant’s ability to take in nutrients and water. Protect the roots from physical damage through careful handling and avoid overwatering, as it can cause root rot.

Regular monitoring of the Anubias rhizome for firmness and a healthy green color can help detect any root-related issues early on. Depending on the severity of the damage to the root system, it may not be possible to return the plant to full health.

An infographic going over 6 Reasons Your Anubias Plant Has Black Leaves!

Role Of Algae And Fungus

An Otoshin eating algae from an Anubias plant leaf
An Otocinclus eating algae from an Anubias plant leaf.

Algae and fungus can be a real problem for Anubias plants and if left unchecked, they can both cause a wide range of problems with black leaves often being an early warning sign of a problem.

In many cases, adding a suitable algae eater to your tank will be a great way to minimise this risk to your Anubias. Here are some recommended algae eaters that can work in most Anubias tank setups:

  1. Otocinclus Catfish: These small, gentle fish are excellent algae eaters, known for their ability to clean plants, glass, and decorations. They prefer to be in groups, so it’s best to keep a small school.
  2. Bristlenose Plecos: These are smaller than most Plecos species and are good at controlling algae without damaging plants. They are a popular choice in planted tanks.
  3. Siamese Algae Eaters: True Siamese Algae Eaters are renowned for their ability to eat a wide variety of algae types that other fish typically ignore, including black beard algae but they can sometimes eat your Anubias so there is a trade off.
  4. Nerite Snails: These snails are popular in planted aquariums because of their voracious appetite for algae. They come in several varieties, each with unique patterns and colors.
  5. Amano Shrimp: Named after the famous aquarist Takashi Amano, these shrimp are excellent algae eaters and are safe with plants. They are efficient cleaners and will work their way through algae (including black beard algae) on leaves, substrate, and decorations.
  6. Cherry Shrimp: These are smaller than Amano shrimp but equally good at eating soft algae. They add a pop of color to the tank and are plant safe.

Black Beard Algae

Black Beard Algae (BBA) is a common issue faced by many aquarists, as it can negatively affect aquatic plants, including Anubias. BBA appears as black spots on plant leaves and can be challenging to remove, causing the leaves to look unsightly.

It often thrives when there are fluctuating CO2 levels in the aquarium and imbalanced nutrient levels, particularly with high amounts of phosphate. To prevent BBA from infesting Anubias leaves, it is crucial to maintain a stable CO2 level and monitor nutrient concentrations with consistent dosages of ferts.

Furthermore, introducing algae-eating species like Amano shrimp and Siamese algae eaters can help control the algae growth by consuming it.

Fungus Related Diseases

Fungus-related diseases can also contribute to blackening Anubias leaves. One common fungal infection is Anubias rot, which primarily affects the rhizome, causing it to become discolored, rotting, and emitting an unpleasant odor. A compromised rhizome may lead to discolored and rotting leaves, which can turn black. To avoid fungal issues, it is essential to:

  • Maintain proper water quality: Keeping the water free of excess organic matter and regularly changing it will help inhibit bacterial and fungal growth.
  • Ensure adequate water flow: Increasing water circulation will help distribute nutrients evenly and facilitate oxygen exchange, preventing stagnant conditions that favor fungal growth.
  • Quarantine new plants: Inspect and quarantine new plants before adding them to your aquarium to prevent introducing infections.
  • Monitor CO2 levels: Maintaining a stable and appropriate CO2 level will help promote healthy plant growth and mitigate the risks of diseases.

Restoring Anubias Health

Anubias plants thriving in an aquarium

Thankfully, there are a number of different things that you can do to help improve the recovery rate of an Anubias plant with black leaves. Most of these can also help increase the survival chance of the plant in extreme cases where the problem has been left to develop for extended periods of time.

Nutrition Supplements

Providing proper nutrients is essential for the overall health of anubias plants. It helps prevent leaves from turning black and maintains their lush green appearance. Regularly add a high-quality liquid fertilizer to your aquarium to ensure anubias receive the necessary nutrients. Consider incorporating the following nutrients if they’re lacking in your tank:

  • Iron (Fe): Needed for chlorophyll synthesis and is a component of many enzymes associated with energy transfer, nitrogen reduction and fixation, and lignin formation.
  • Nitrogen (N): Required for the synthesis of amino acids, proteins, and nucleic acids.
  • Phosphorus (P): Important for energy transfer and storage.
  • Potassium (K): Needed for many physiological processes such as protein synthesis, opening and closing stomata, and maintaining turgor pressure.
  • Calcium (Ca): Essential for the structure of cell walls and membranes, and plays a crucial role in cell division.
  • Magnesium (Mg): Core component of chlorophyll, the molecule that gives plants their green color and carries out photosynthesis.
  • Sulfur (S): Required for the production of certain amino acids and proteins.

Appropriate Lighting

Anubias plants are low-light species, which means excessive or direct lighting can harm them. Excess light can lead to the growth of black algae on leaves, causing them to turn black. To prevent this, follow these guidelines:

  • Ensure the aquarium receives indirect lighting instead of direct exposure to sunlight.
  • Limit the duration of artificial lighting to 7-8 hours per day.
  • Use low-intensity LED or T8 lights for indoor aquariums.

Fixing Water Conditions

Maintaining stable water parameters is crucial for keeping anubias healthy. It’s important to monitor and adjust water conditions regularly, as necessary. Here are some key aspects to pay attention to:

  1. Water changes: Perform regular water changes, approximately every 1-2 weeks, to help decrease the build-up of algae and improve water quality.
  2. Water temperature: Anubias thrive in water temperatures between 72-82°F. Keep the temperature stable to avoid stress on the plants.
  3. pH levels: Maintain the pH of your aquarium between 6.0 and 7.5 to create a conducive environment for anubias growth.

By addressing these crucial factors—including nutrition supplements, appropriate lighting, and fixing water conditions—you can help restore the health of your anubias plants and prevent their leaves from turning black.

Preventing Your Anubias Leaves Turning Black In The Future

A number of Anubias plants free from black or brown marks on their leaves

One of the primary reasons for anubias leaves turning black is due to an excess of light reaching the plant. To prevent this issue, you should consider reducing the exposure of the anubias plant to light sources. Keep the anubias plant in a shaded area, as it generally thrives under low to moderate light conditions. Moreover, maintain a consistent light schedule that provides about 7 to 8 hours of light daily to ensure optimal growth.

Certain conditions like algae growth and poor water quality can also contribute to the blackening of anubias leaves. To maintain ideal water parameters, make sure to conduct regular water changes and keep a close eye on nutrient levels. Additionally, using a good filtration system can help in keeping the water quality stable and the algae growth in check.

It’s important to prune damaged or blackened leaves from the anubias plant to prevent the spread of any disease or algae. This also allows for new and healthy growth on the plant. Make sure to use clean and sterilized tools for pruning to avoid any chances of infections.

Finally, ensure that the anubias rhizome is not buried in the substrate, as it can cause the rhizome to rot, leading to discolored leaves. Planting the anubias on a porous surface like driftwood or rocks can be an effective method of preventing rhizome rot and keeping the leaves healthy.

By taking these preventive measures, you can avoid the issue of anubias leaves turning black in the future and enjoy a healthy, thriving aquatic plant in your aquarium.

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