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How to Get Rid of Black Beard Algae in Aquariums: Causes & Removal Tips

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By Lindsey Stanton


Have you noticed dark, hair-like growths appearing on items in your tank and aren’t sure what it is? You may be dealing with Black Beard algae.

Black Beard algae can settle on just about any solid surface in your tank, including décor, plants, substrate, and even slow-moving invertebrates like snails. If you’ve noticed these unusual algae popping up across your tank and aren’t sure what to do, let’s talk about it!

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What is Black Beard Algae?

Black Beard algae is a variety of algae that is easily distinguishable from its dark coloration and fuzzy appearance, taking on a beard-like appearance as it grows longer and fuller. It is usually black, dark green, or dark grey, but you may notice a reddish tone as well.

You’ll often notice Black Beard algae starting out in small patches on the tips of plant leaves or across your tank’s substrate. Over time, this algae will take on a much fuller appearance, blacking out whatever it is growing on.

Image Credit: Joan Carles Juarez, Shutterstock

This algae is also sometimes called Brush algae because when it starts off as small tufts, it looks similar to soft brushes like makeup brushes or paint brushes.

Don’t confuse Black Beard algae with Staghorn algae, which also has a hair-like appearance. Staghorn algae grows into more of an antler shape while Black Beard algae grows more like hair. Over time, Staghorn algae takes on a stringy appearance while Black Beard algae continues to grow fuller and longer.

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Is Having Black Beard Algae a Problem?

The answer to this question isn’t as straightforward as you might think.

Black Beard algae actually isn’t inherently bad. It can make for an interesting focal point in tanks if it’s kept in check. Keeping it in check is the trick, though. If you’re a beginner aquarist, a less invasive plant is probably better for you, so getting rid of Black Beard algae should be a priority if you see it starting to pop up in your tank.

Black Beard algae can be an indicator of a problem because it thrives in low CO2 environments. If you have Black Beard algae showing up and you are using some kind of CO2 injection, then there may be something wrong with your injector.

CO2 is needed for most plants to thrive and without it, simpler plant forms like algae will take over, stealing nutrients from other plants in the process.

Black Beard algae also can kill off other plants if allowed to grow too large or thick because it will begin to block light to other plants, allowing the algae to thrive while the other plants suffer.

Image By: Joan Carles Juarez, Shutterstock

What Causes Black Beard Algae?

We know what allows Black Beard algae to thrive, but what causes it in the first place? Black Beard algae spreads easily, so it can be introduced into tanks via contaminated water from new aquatic life, including fish and plants.

It can also get into your tank if you put secondhand tank equipment into your tank, including gravel, décor, and filters, so make sure anything secondhand you put in your tank has been thoroughly, but safely, cleaned.

Black Beard algae can reproduce from tiny pieces, so attempting to manually remove these algae inside of your tank can result in it spreading across more of the tank.

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How Do I Get Rid of Black Beard Algae?

1. Removal

Trim any leaves from plants that you notice Black Beard algae growing on. Do not pick the algae off the leaves, just remove the leaves from the tank entirely. Plants can be removed and dipped for 2-5 minutes in a 10% bleach water solution.

Remove décor or equipment from the tank where Black Beard algae has taken hold. Once removed from the tank, these items can be soaked in a 10% bleach water solution or rinsed with clean water and scrubbed with a toothbrush. Do not put bleach into your tank and do not scrub items inside of the tank.

If the algae is spotted across the tank’s substrate, you may be able to remove portions of the substrate and throw it out. If the algae is more diffusely spread, you may need to remove and replace your substrate.

Remember that removing and cleaning multiple items or pieces of equipment from your tank all at once can result in your tank cycle crashing. If you are able to, keep filter media like bio sponges and ceramic rings in the tank to maintain your beneficial bacteria colony.

Close up of scissors and tweezers pruning aquatic plants in a fish tank. Aquarium maintenance
Image Credit: Ladanifer, Shutterstock

2. CO2

CO2 can be supplemented in your tank with products like API CO2 Booster or Seachem Flourish, both of which are carbon-based products.

Pressurized CO2 injection can be used to increase the CO2 levels in your tank as well. This can be achieved with a small system like the Fluval Mini Pressurized CO2 Kit, or a larger system like the FZONE Pro Series Dual Stage CO2 Regulator.

3. Animals

Very few fish will eat Black Beard algae, but true Siamese algae eaters will usually eat it. You will have to verify with your supplier that the fish you are purchasing is a true Siamese algae eater since other similar fish may be marketed under the same name.

Many varieties of shrimps, like Neocaridinas and Caridinas, will happily snack on Black Beard algae. However, they are so small that it will take a lot of them to get the algae under control if you have a large amount of algae.

Image Credit: To Be Determined, Shutterstock

4. Decrease Light

Black Beard algae thrives off of light, which means that decreasing the amount or strength of light your tank receives every day can help kill off the algae. This may involve relocating your tank to a place where it receives less natural light or making alterations to your tank lighting schedule.

Purchasing a light that allows you to make adjustments to light level and how much light your tank receives at different points in the day can help reduce excessive lighting in your tank. Products like the Current USA Satellite Plus Pro Freshwater Aquarium LED light or the Fluval Aquasky LED

5. Copper

Seachem Cupramine Copper

Copper is a last-ditch treatment option for Black Beard algae.

Copper products, like Seachem Cupramine, can kill Black Beard algae. However, Copper-based products can kill desirable plants and definitely will kill invertebrates like snails and shrimp.

If you choose to use a Copper product to treat your tank for Black Beard algae, it is of the utmost importance that you dose it based on the manufacturer’s instructions. Copper is a heavy metal and will stay in the tank for a long time, even with water changes, so it can be weeks to months before your tank may be safe for plants, invertebrates, and sensitive fish.


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Black Beard algae can be a real hassle to get rid of, so prevention is key! If you intentionally allow Black Beard algae to grow in your tank, you will need to keep a close eye on it and routinely maintain it to prevent it from taking over your tank.

If you are dealing with Black Beard algae, you’ll quickly learn that the hardest part of treating it is waiting. This algae doesn’t take over a tank overnight, it can take weeks for it to get a significant foothold. This means that getting rid of Black Beard algae isn’t going to be an overnight thing. You will have to patiently treat your tank and maintain water quality with weekly water changes and close monitoring of your water parameters. If the algae begins to die off, it can create an ammonia spike in your tank.

You’ll know you’re starting to win your fight against the algae when you notice it taking on a bright or dark red coloration. This is often the color Black Beard algae will turn right as it is dying.

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Featured Image Credit: Joan Carles Juarez, Shutterstock

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