Black Beard Algae: All you need to know

There are hundreds of thousands of different types of algae; some of these can end up growing in your aquarium. One of these is Blackbeard Algae.

You may notice purple, brown or black fluffy tufts growing on the plants, glass or decor in your aquarium.

But what is it?

What is black beard algae?

Black Beard, or Black Brush Algae, is a type of Red Hair Algae – it grows on surfaces and spreads much like grass.

As it is an algae, it survives by feeding on nutrients in the water, minerals, nitrates and light.

Blackbeard algae is found in freshwater environments around the world, but grows in  a set of ideal conditions. These are typically warmer waters with a high concentration of iron and calcium in them.

This makes fish tanks ideal for them as they are clean bodies of water with high nutrient and high mineral contents, due to the fish living in them.

Is black beard algae harmful?

No, blackbeard algae is completely harmless, it will not hurt you or your fish.

The only issue it poses is that it grows over the leaves of live plants and swamps them, blocking light from the leaves and starving the plant of nutrients.

Bad cases of blackbeard algae growth can kill plants.

Blackbeard algae can also grow within the pipes of your filtration and inhibit the flow, so it should be removed from pipework if it grows there.

Is black beard algae beneficial?

In many ways yes, blackbeard algae is beneficial. As it is an algae, it will consume excess minerals and nutrients from the water column.

As it grows it also provides spaces for infusoria to grow and allows fish to graze on it.

Blackbeard algae is also much better than plants at extracting certain nutrients from the water, so it can remove a large portion of the nitrates from water.

It can also prevent the tank from becoming too mineralised and will gradually reduce hardness as it consumes calcium from the water – this can be good if you have hard tap water but want to keep soft water fishes.

Why do I have black beard algae?

The number one cause for blackbeard algae is water that contains too much iron.

It thrives in warm, alkaline waters with high mineral contents. If you have a planted tank, then the chances are you will eventually encounter it at some point.

Blackbeard algae also enjoys tanks which have a little water movement; it needs a good amount of gaseous exchange in order to grow.

It can be introduced on a plant or any second hand decor or equipment.

What causes black beard algae?

Algaes reproduce via a spore or by splitting apart and growing over different areas. This means that once blackbeard algae is in a tank, it can grow pretty much anywhere as it takes advantage of water movement to release its spores everywhere.

Do you need to remove black beard algae?

You only really need to remove blackbeard algae if either you dislike its appearance and want rid of it, or if it opposes a threat to the livelihood of your aquatic ecosystem.

The only ways it can do this is if it grows in the filter and blocks flow, or emulsifies your live plants and kills them.

The former of the two is actually quite a rare occurrence, it only really happens if you have clear pipes as blackbeard algae needs light to grow; it usually will not grow within your filter or pipes.

If it grows on plants to a point where the whole plant is covered, then you need to remove it, or it can kill the plant.

How to remove black beard algae

If you decide you want to remove blackbeard algae, be aware that this isn’t easy, it is one of the hardest algaes to get rid of.

However, there are methods on doing it, with varying levels of success. 

Remove by hand

The first method is to remove it by hand. This is more difficult than it sounds, as the tufts are rooted down firmly and are difficult to grasp. While it can be done this way, it takes a long time, can damage plants and is fighting a losing battle as the algae will just grow somewhere else.

While you may never be able to fully eradicate it, if you adopt pruning algae covered plant leaves into your regular maintenance schedule, then this is a good way to avoid it overtaking with minimal costs and effort.

Pruned plant leaves will grow back, so do not worry that this is killing your plant, you are simply preventing the further spread of blackbeard algae.

Reduce nitrate levels

The second method is to reduce the nutrient level in your tank.

  • Do more water changes
  • Feed less
  • Have the light on for less time
  • Don’t add plant fertiliser

This will weaken the algae and make it easier to remove by hand, or it will just die back on its own. This method is not that effective though, as blackbeard algae is very hardy, and your plants may suffer from the lack of nutrients.

You can also use chemical solutions to remove it. Seachem Flourish can be applied to affected areas directly – this is especially effective on live plants as it is not toxic to harm the plant, but will kill off the algae.

You can also dose Seachem Flourish regularly, just be careful not to overdose it, use the recommended amount on the bottle.

You can also use animals to eat the algae. Unfortunately, there aren’t many things that can eat blackbeard algae and the ones that do eat it have specific care requirements, which we will discuss later on in the page.

How to get rid of black beard algae in a pond

If you live in a cooler climate, then you don’t have much to worry about, as blackbeard algae does not like cold temperatures. If however, you live in a tropical area where it does grow, then use the same techniques as you would in a tank. 

You can also take out decor like rocks and wood and pour boiling water on them, or soak them in saltwater to help kill the algae, then give them a really good brush to remove it.

How to get rid of black beard algae from plants

As mentioned, you can use seachem flourish to do this. 

  1. Take your plants out of the aquarium and allow them to dry out for a minute or so.
  2. Then apply with a pipet the chemical, just apply it directly to the algae itself in small amounts (You can also do this with a paint brush and go over the affected areas).
  3. Once you have done this, leave it to stand for 5 minutes and then place the plant back into your aquarium.
  4. Do this regularly until the algae has gone.

How to get rid of black beard algae on driftwood

Driftwood swimming in fish tank

As driftwood isn’t alive, you can try a few more things to get rid of invading blackbeard algae on it.

The first thing you can do is brush it really hard for a while – this will remove most of the larger tufts of algae, but will not stop it from growing.

You can also soak the wood in boiling water or salt water to try to kill off the algae, and then scrub it with a coarse brush.

You can also use seachem flourish the same as you would on the plants, or even hydrogen peroxide, but be warned that this peroxide will kill your fish if it gets into the water.

Be sure to thoroughly rinse the wood afterwards if you decide to do this.

Fish that eat black beard algae

Siamese eating algae

Through our experience and discussion with many seasoned aquarists, we have found that In short, there aren’t many animals that eat it at all.

We have tried hundreds of different fish on blackbeard algae to see if they eat it, so far we have only found a handful, and none of them seem to enjoy it, mainly only nibbling at it.

What fish eat black beard algae?

The three main fish species that eat blackbeard algae are Florida Flagfish, Siamese Algae Eaters (SAE), and Siamese Flying Fox.

All three of these fish however, have specific care requirements and aren’t ideal for every tank. Both siamese algae eaters and flying fox are part of the carp family and get quite large, they are closely related to redtail sharks and have similar temperaments.

Flying fox and SAE are mainly wild caught or are bred using hormones and shipped in from abroad as they are hard to breed in aquariums.

This is because their life cycle is not fully understood and they are near impossible to sex.

Both of these fish grow very fast and as they become older, will become aggressive towards other fish. SAE are the more placid of the two but will still chase other fish around.

Both will get around 8” in length, both like to live in schools and both are open water swimmers, so a large tank is needed for them.

Both of these fish will eat blackbeard algae, but they will not eat it all in one night, they really just nibble on it when they are hungry. As they age, they will also eat less and less algae and need more protein rich foods as their main diet.

Flagfish will pull on blackbeard algae and eat it in small amounts, but they will also tear up your live plants if you have anything with soft leaves. 

Flagfish are also fin nippers and will eat small fish and shrimp if kept in a community tank, but they do not get very large, staying around 2”. They are also temperate, which makes them more suitable for cooler tanks, whereas SAE and flying fox are tropical and need temps around 25C or 77F.

Do shrimp eat black beard algae?

Most shrimp will not eat blackbeard algae. Amano shrimp may graze on it a little, but they will not make much of a difference on it, unless in very large numbers.

Crayfish may also pull at blackbeard algae, especially dwarf crayfish, but they again are not good at eating it.

Do snails eat black beard algae?

We have tested many snail species on blackbeard algae too, but so far have found no snails that will eat it.

We have tried all the obvious options, as well as some less commonly known species, even a couple marine species too!

None of these snails will eat blackbeard algae – they seem to graze on it in search of food trapped within, but will not eat the algae directly.

How to prevent black beard algae

The best way to avoid black beard algae is through preventative measures.

By this we mean regular tank maintenance, water changes to remove excess nutrients every week, a regular feeding schedule, regular filter cleaning and algae scrubbing.

Regularly prune covered plant leaves and remove decor which is growing blackbeard algae.

You can also add more red live plants, as these consume iron in the water, which blackbeard algae needs to survive.

You can also add a timer to your lights so they get a good balance of night and day; sometimes being a little off and letting too much light in your aquarium can cause an outbreak.

Treating black beard algae with hydrogen peroxide

Using this method to remove blackbeard algae is risky as peroxide is poisonous and will kill fish if it enters the water column.

  1. The way to properly use it, is to take out plants and decor covered in algae and dip them in hydrogen peroxide for 2 minutes, or use a spray bottle and mist over the leaves with the peroxide.
  1. Then rinse the plants or decor very thoroughly with clean freshwater.
  1. Finally, add them back to the tank and the peroxide should have killed the algae.

In a few days, it will melt away and the plants will be clear.

Just be extremely careful and make sure you wash the entire piece before adding it back to your tank. Peroxide can be devastating even in small amounts.

Will vinegar kill black beard algae?

If you have distilled white vinegar, you can use it as an alternative to peroxide to kill off invading algae. Adopt a similar method with the peroxide treatment, and avoid getting it in your water.

As vinegar is an acid, it will drop the pH of your tank significantly if it enters the water.

Be sure to thoroughly wash materials that have come into contact with it before adding them back to your tank.


After all the effort some go through to remove blackbeard algae, it still manages to return. In some cases, people just accept removing blackbeard from their tank by hand, and add it to their regular tank maintenance routine.

Hopefully by reading our page you can gather a better understanding of it.

In short, the algae does not harm your fish, and is only damaging if it grows in pipes and blocks the flow, or if it grows on weak plants.

Plants usually do a pretty good job of deterring algae from growing on their leaves; a plant covered in blackbeard is normally one that isn’t doing too great in the first place.

Keep your plants healthy and well fed and they should have little issue with blackbeard algae.

If they are covered, then the simplest method is to prune the covered leaves. This will stop the further spread of the algae and will allow the plant to grow a new leaf, free from pests.

Try to also avoid adding too much iron to your tank – check the ingredients on bottles of plant fertiliser to see how much iron they contain.

If you have blackbeard in your tank, it is likely that it is feeding on the excess iron from plant ferts.

Try to cut back on the amount used, stop using ferts entirely, or try a different type of fertiliser if possible.

If you find blackbeard unsightly, then there are many ways to get rid of it. Start small first and if it proves to be tough, then try the more extreme methods; just be careful when using chemicals as they can harm your fish.

On the contrary, some find blackbeard algae to have a pleasant appeal as it covers rocks and driftwood like a thick blanket of moss. Not only this, it is even beneficial in some ways, as it does consume nutrients and helps keep the water clean.

3 thoughts on “Black Beard Algae: All you need to know”

  1. Hi,
    I raise red ramshorn snails just for black beard algae. Back in the early 1970s when I was A kid we didn’t have Blackbeard algae in our tanks. When we moved I didn’t restart my tank and didn’t get another one until much later in life. At this point I was ignorant to black beard algae and purchased some live plants Java fern that had the edges with a little black algae on. I had no idea how stupid it was to buy those. Since my tanks are all heavily planted are used to plant fertilizer which made the black beard algae go crazy. I have a few Picasa mess that will eat it. I drop a handful of a red Ramshorn snails onto a rock or a plant with black beard algae on it and they will clean it. I’ve used bleach and peroxide mixtures with water on life plants as long as you don’t get it on the routes. Everything I’ve read on the Internet that tells you how to do it didn’t seem to phase it. Are use probably 70% bleach water on the leaves rinsed them good put them back in the water and within a few hours it turns white. Then I get a Scotch-Brite pad and I know you think this sounds harsh and gently wipe it off the leaves then rinse again. Anybody that says it’s easy to get rid of has not battled it before. I myself like a lot of others didn’t know what it was called to research it and by then it had a pretty good hold on several of my tanks. I have one rather large chocolate Pleco that seems to eat it, and I think the Siamese algae eaters Might help to some degree, that’s all I’ve actually seen do anything other than the red Ramshorn snails which really made a difference. I hope this was some help at all do anybody plagued with black beard algae.

    • Hi Mark,
      Thank you so much for your insightful comment, this information is extremely useful!

      I am surprised your red ramshorns eat it, I have hundreds of them in my tanks and they don’t touch the Blackbeard at all haha.
      Maybe you have bred a specific strain of Blackbeard eating Ramshorn snails.

      when I used to work in the aquatics stores, it would grow on the back glass all the time, I tried everything on it to see what would eat it and only found florida flagfish, flying fox and and siamese algae eaters would touch it, and they would never eat it in large amounts, only peck at it.

      Bleackbeard algae is definitely tough to get rid of and it is still not as commonly talked about as it probably should be, but we are glad to hear you have found a way to effectively combat it, thank you again for sharing!


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