Black Beard Algae
Black Beard Algae


Black Beard Algae, also known as Black Brush Algae (BBA) or Audouinella is a challenging algae to remove from a planted aquarium.  BBA is a form of red algae (Rhodophytes) that has adapted from the typical saltwater environment conditions to freshwater.  BBA like other red algaes, contain a red protein used for photosynthesizing light called phycoerythrin.  Phycoerythrin harvests purple and red wavelengths, and reflects green. This makes the BBA appear dark purple and black.

Black Beard Algae is characterized by it thick black clusters that grow in aquariums that have either too much light and inadequate carbon dioxide levels, or too little light and inconsistent carbon dioxide levels.  The black feather strands form half-inch tall tuffs which grow on almost anything. It is a pervasive algae that proliferates on the edges of slow growing leafy plants such as Amazon Swords, Java Ferns, Bolbitus and Anubias.  It also has the tendency to linger on rocks, driftwood, and aquarium equipment i.e. spraybars, intakes and other tubing.  If left unchecked, this algae has the capability to cover the entire plant and block light from penetrating to the plant’s leaves. 

Algae Removal Tips

Manual Removal

Black Brush/Beard Algae is easily removed with a razor blade, or plastic scrapper. Remove any effected leaves and scrub aquarium equipment and hardscape materials well.   Infected gravel should also be removed and scrubbed down.   Remember to do a waterchange and clean out your filter.

Chemical Removal

Many hobbyists have found Seachem Excel to be an effective tool towards combating and preventing algae. A daily regular dose of Excel will weaken BBA to where it either disappears or becomes easily removed by hand. Applying Seachem Excel directly, via syringe, to the infect areas is the most effective way of applying this method.   After 3-5 days you’ll notice the BBA dissolving/dying from an infected area..

Cleaning equipment and dipping plants in a bleach solution (2 parts bleach: 5 parts water) for 3-5 seconds will kill BBA as well. When dosing excel or bleach dipping, you’ll see the BBA turn from black to gray/red, and then white. 

Nutrients and Circulation

As mentioned previously, Black Brush/Beard algae is caused by fluctuating or inadequate carbon dioxide (CO2) levels.  In high light tanks, ensure a consistent and high dosage of dissolved CO2 (25-30 ppm). In lower light tanks, remember that tap water contains dissolved carbon dioxide and frequent water changes can cause large fluctuations in CO2 levels. In this scenario, less frequent water changes will help reduce the variations in CO2 levels.   It may also be beneficial to introduce a liquid CO2 supplement such as Seachem Excel to help plants grow successfully.


Siamese Algae-Eaters, Crossocheilus siamensis, are the go to fish species for controlling Black Beard/Brush Algae. They are most effective against when BBA first begins to appear.  If a tank is already overly infected, remove the infected areas on plants and scrub hardscape/aquarium equipment, then introduce Siamese Algae Eaters.  These fish will eat and keep BBA in check.  Some Siamese Algae Eaters are uninterested in eating BBA if fish food is readily available, so feed less fish food to encourage the fish to eat the algae clumps.

The Amano shrimp, Caridina multidentata (formerly known as Caridina japonica), will also pick at BBA , thereby maintaining it, but it is not very effective at removing BBA entirely.


Remember, BBA thrives in planted aquariums with fluctuating CO2 levels.   Black Brush/Beard Algae is best prevented by ensuring consistent carbon dioxide levels in the tank.  If you do notice BBA starting to appear, remove any infected areas before they get out of control.

Algae Profile
Scientific Name: Audouinella
Common Name: Black Beard Algae
Difficulty to Remove: Moderate
Potential Causes: Low CO2/High Light
Characteristics: Black Tuffs
Algae Removal Procedure: Increase CO2