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How to Get Rid of Black Beard Algae ( Black Brush Algae) in Aquarium

Black Beard Algae or Brush Algae is one of the most common types and also the most difficult algae that you can’t get rid of easily.

It belongs to the family of red algae, although it’s not red.

Keeping your tank free of algae is necessary to maintain the health of your fish and plants.

In this article, we’ll explain why Black Beard Algae grow in your aquarium and how to get rid of its stubborn growth.

What is Black Beard Algae?

Black Brush Algae or BBA is a hardy alga that is very difficult to eliminate. It’s usually black or grayish and grows on the surface of slow-growing plants, as well as rocks, filters, and decorative items in your tank.

Just like other algae, BBA reproduces through spores that can be introduced to your tank via new fish or plants. When the conditions are right, the algae will start to grow uncontrollably. It usually clings to surfaces and feels slippery so it’s quite difficult to remove by hand.

Most fish don’t eat the Black Beard Algae, although a few breeds can consume it like the Florida Flag Fish or the Siamese Algae Eater. It’s not a harmful alga but it affects the aesthetics of your fish tank.

Moreover, it feeds on the nutrients in the water, thus affecting the health of your fish and plants in the long run. This is commonly saltwater algae but it occasionally grows in freshwater tanks.

How to Identify the Black Beard Algae?

In the early stages, the BBA will appear as black or grayish spots that grow on any surface in your tank. It looks different from other types like the Staghorn Algae that look the horns of a deer. Black Beard Algae will look like packed bristles that keep on growing in the shape of a beard until they look like strands of black hair.

When kept untreated, the algae will look like ugly patches of hair floating in your fish tank. The patches keep on growing on the edges of plants until they fully cover the leaves. This might limit the fish access to plants and other hiding spots so they might feel stressed out.

Why Do Black Beard Algae Grow in a Tank?

There are several reasons why you would start seeing the Black Beard Algae in your tank.

  • You have introduced a new item into the tank. If you have introduced a new plant, décor item or fish that has some algae spores on the surface or body, then the algae are likely to grow and flourish.
  • Having an excess amount of B12 in the water also helps the algae to grow. Keeping an eye on the water chemistry by doing regular changes and testing is recommended, so you can notice the slightest changes.
  • If you haven’t installed a potent filtration system, you’ll start to see more of the Black Beard Algae. These algae prefer to live in water that has high levels of nitrites so the lack of a filtration system is one of the main causes of their spread.
  • The lack or fluctuation of CO2 is another reason why these algae will grow in your freshwater or saltwater tank. Carbon dioxide is naturally found in the fish tank as the fish breathe oxygen and give out carbon dioxide.

This carbon dioxide is later consumed by plants. If you don’t have enough plants in your tank, the level of carbon dioxide will increase, thus affecting the health of your fish and increasing the growth of the BBA.

  • Although some fish can eat the Black Beard Algae, this is not possible if the water has a high concentration of calcium. The calcium is deposited in the body of the algae and it becomes harder to consume.
  • Too much light in the tank is likely to make the algae spread and grow. Aquarium lights are needed to help your aquarium plants stay in perfect health. However, these lights also promote the growth of the BBA.
  • Overfeeding the fish means that there will be excess nutrients in the tank. Excessive nutrients encourage the growth of unwanted BBA.

Will Black Beard Algae Harm Your Fish?

The short answer is no. The BBA isn’t poisonous and won’t harm different types of fish in your aquarium. However, there are several reasons why you need to get rid of it as soon as possible.

  • The fast-growing algae block access to hiding places that most bottom dwellers and shy fish like to roam around.
  • The BBA deprives nocturnal fish of their shelter as the growth blocks access to areas under the plants.
  • The Black Beard Algae clings to every hard surface in your tank, including snails thus turning your tank into a black mess of hair-like growth when left unattended.
  • More active fish will be deprived of the space they need for swimming. This means that the fish are likely to grow more aggressive because they’re stressed out.

Will Black Beard Algae Harm Your Plants?

Aquatic plants are essential to keep your aquarium balanced. Without them, there will be a change in the nutrients level and an increase in carbon dioxide levels that can eventually harm your fish.

BBA doesn’t kill your fish, but will most likely kill the plants in your tank. The Black Beard Algae don’t produce toxins or harmful chemicals, but slowly smother the plants in your tank.

A small spot of algae isn’t a big problem. But as the algae growth manifests, the plant won’t be able to perform the process of photosynthesis and will eventually die.

5 Ways to Get Rid of Black Beard Algae

Luckily, there are several methods that will help you get rid of the Black Beard Algae before the growth spreads to every corner of your aquarium. Some methods are more potent than others.

1. Removing the Black Beard Algae By Algae Scraper

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This is probably the most straightforward way to get rid of the BBA.

It involves strong scrubbing of the walls, corners, and other hard surfaces found in your tank using hot water.


  • Inexpensive way of removing the BBA.


  • Bleach or cleaning detergent might be needed to remove all the algae.
  • Doesn’t remove the BBA from the surface of plants and the back of shells and snails.

2. Using Heat

Video: “How To Get Rid Of Black Beard Algae Without Chemicals!”

This method works if you want to go chemical-free. You’ll simply remove all artificial plants and ornaments from the tank and boil them.

The algae are killed on the spot and you’ll be able to put these items back into your tank. However, it goes without saying that this method doesn’t work with live aquatic plants.


Fast way to get rid of all the algae growth on ornaments and fake plants


  • Doesn’t work with live plants.
  • Doesn’t affect the growth of algae on other objects that can’t be removed from the tank.
  • Some porous rocks might explode when heated.

3. Introducing Algae Eating Fish and Shrimp

Video: “BBA infested planted aquarium cured”

Only a few fish and crustaceans prefer to eat the BBA. For example, the Siamese Algae Eater Fish, Florida Flag Fish, Cherry Shrimp, and Amano Shrimp can be used to get rid of the BBA.

The shrimp work for smaller aquariums and will do their job over time. The Siamese Algae Eater Fish are big, reaching a size of 20 cm so they will only live in a tank of 20 gallons or more. Here are some of the pros and cons of this method.


  • Effortless way as the fish and shrimp will do the job on your behalf.


  • Although some fish can eat the Black Beard Algae, this is not possible if the water has a high concentration of calcium. The calcium is deposited in the body of the algae and it becomes harder to consume.
  • Some of these animals will only eat algae when there are no other nutrients available. This means that other fish in your tank might starve because there isn’t enough food.

4. Treating the Tank with Hydrogen Peroxide

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In the case of a serious infestation, treating the water with hydrogen peroxide might be the best solution. You can remove décor items, rocks, and fake plants, and then soak them in diluted 3% hydrogen peroxide.

However, this method won’t work if the algae are spreading to every corner in your tank. In this case, you might need to apply the hydrogen peroxide to the tank.

Never apply hydrogen peroxide to the tank water as long as you have fish, shrimp, snail or any other living creature in it!

  • Fast and potent way that gets rid of the BBA.


  • You need to repeat this process for a few days.
  • The plants in your aquarium are likely to get affected. Their colors might fade and they might die.
  • Fish, shrimp, and snails that live your tank might get affected. It’s recommended that you move them to another tank until you’ve stopped applying the hydrogen peroxide.

5. Boosting the Level of Carbon Dioxide in the Aquarium

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This is the most practical and safest way that will help you get rid of the stubborn and fast-growing algae without affecting the inhabitants of the tank. Increasing the level of carbon dioxide won’t kill the BBA on the spot, but will gradually inhibit its growth until it eventually dies.

Increasing the level of CO2 guarantees that your plants are more likely to flourish and become stronger thus competing with the algae for nutrients. As a result, the algae won’t have enough nutrients and will eventually die.

A potent and safe product that you can use to get rid of the Black Beard Algae is the Seachem Flourish Excel Bioavailable Carbon. It boosts the level of carbon dioxide safely while providing other nutrients like ferrous iron that your aquatic plants need.

Improves the photosynthesis process

This is liquid carbon which is a safe alternative to carbon injection which can mess up with the pH level of your tank. This product improves the photosynthesis process of the plants by introducing the already finished carbon compounds, thus helping the plants flourish. At the same time, it’s safe to use around fish, shrimp, and snails.

Seachem Flourish Excel Bioavailable Carbon also contains an active ingredient; Glutaraldehyde which prevents the spread of the Black Beard Algae in your tank and gets rid of it.

In cases of serious infestation, you might need to apply the product directly to the plant. This means that you should remove the plant, let it dry, and apply the formula using a small brush to the infected areas. Repeating the process might be necessary, depending on how serious the infestation is.

After applying the product and letting it dry, you should put your plant back into the aquarium. After a few days, you’ll see that the algae have started to fade and will eventually die out.


  • Safe and practical way to get rid of the Black Beard Algae.
  • Boosts the growth of aquatic plants.
  • Doesn’t damage the plant parts, unlike bleach.
  • Doesn’t affect the pH level of the water.
  • Safe to use around fish, shrimp, and snails.


  • You might need to repeat the treatments until all the Black Beard Algae is gone.

Check Price and Reviews on Amazon

Video: “Flourish Excel vs. Black Beard Algae”

How to Prevent the Black Beard Algae

Prevention is definitely better than any cure. Here are some tips that can help prevent the growth of the Black Beard Algae in your aquarium.

  • Keep new fish in a separate tank to make sure that they’re not sick. This method also works to prevent the introduction of different types of algae, including the BBA.
  • Clean any new plant, live or fake before putting it in your tank. Giving the plants a hydrogen peroxide bath will remove any parasites as well as algae spores.
  • Avoid adding plants and aquatic animals that you’ve got from the wild.
  • Stick to a strict schedule of water changes to prevent the growth of all types of algae.
  • Install a potent filtration system that keeps the levels of different chemicals in check.
  • Use the Seachem Flourish Excel Bioavailable Carbon as a penetrative method.

Wrap Up

The Black Beard Algae are stubborn and can affect the health of your fish and aquatic plants in the long run. However, getting rid of the growth isn’t impossible.

Using a product that increases the carbon dioxide level without affecting the pH level is the most practical and safest way to get rid of the BBA. Make sure that you keep an eye on your tank to act promptly whenever you see the first growth of the algae as this will make your job a lot easier.

Aaron Boyd
Aaron Boyd

Hello, I’m Aaron Boyd, the proud owner and author behind Aqua Movement. I hope my article was able to answer your questions. If you want to learn more about me, click the home icon above.

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