How To Get Rid Of Black Algae In Fish Tank [5 Proven Tips]

Black algae is a common nuisance among fish tanks. It can be unsightly and difficult to get rid of.

There are many products on the market that promise to get rid of black algae, but some of these products may be harmful to your fish or aquarium plants.

In this article, we will discuss five tips for getting rid of black algae in your fish tank.

How To Get Rid Of Black Algae In Fish Tank?

Black algae are one of the most common problems in aquariums and ponds.

Many people wonder how to get rid of black algae in a fish tank?

So we decided to write this article on how to deal with black algae, and how to prevent them from appearing again. Also, we will be sharing how to treat black algae in a fish tank.

Black Algae are also known as Black Brush Algae, and they come up mostly on glass or plastic surfaces of the aquarium.

They can be dangerous for your fish because it uses oxygen which is needed by the fish!

Before knowing the tips, let us first know what actually causes black algae in fish tanks!

What Causes Black Algae In Aquariums?

There are a number of reasons that can cause black algae to grow in your aquarium.

The most common reason for the growth of black algae is high levels of phosphate and nitrate in the tank water.

These nutrients provide an excellent environment for black algae to grow.

Other reasons for the growth of black algae can include poor water circulation, too much light, and high levels of organic matter in the tank.

Black algae can be harmful to your fish if left untreated.

The algae will compete with the healthy plants and other organisms for food and oxygen, which can lead to their eventual death.

The black algae can also grow on the fish, causing them to become tangled and unable to swim properly.

This will eventually lead to their starvation or suffocation if you do not get rid of it quickly enough.

So now you know, the causes of black algae and how it can be harmful to your fish, let’s move on to how you can get rid of it.

5 Tips To Get Rid Of Black Algae In Fish Tank

In this section, we will be discussing five tips to help get rid of black algae in your fish tank.

Tip #1: Make Sure You Are Using a High-Quality Filter

A good quality filter is important for maintaining a healthy and clean aquarium.

If your filter is not working properly, it can lead to an increase in black algae growth.

Filter helps to remove dirt, debris, and other unwanted material from the water which can help to reduce black algae growth.

Tip #2: Keep The Aquarium Well-Lit

A well-lit aquarium will help to discourage black algae growth.

When light is not present, algae will often times grow more rapidly.

Make sure to keep your aquarium well-lit and you should be able to prevent black algae from growing.

Keeping your fish tank lit will also allow your plants to grow and flourish.

Tip #3: Add Black Algae Eating Fish In The Tank

Adding some black algae-eating fish to the tank is another good way how to get rid of black algae in the aquarium.

Here are some great black algae eaters for your fish tank:

  • Plecostomus (Hypostomus plecostomus)
  • Siamese Algae Eater (Crossocheilus siamensis)
  • Chinese Algae Eater (Gyrinocheilus aymonieri)
  • Australian Rainbowfish (Melanotaenia fluviatilis)
  • Head and Tail Light Tetras (Hemigrammus ocellifer) etc.

These fish will help to keep the black algae under control and will not harm any of your other fish.

Tip #4: Ensure Optimal Water Quality

Black algae have a much higher chance of growing in dirty water than cleaner water, so it is important that you keep the tank clean at all times.

An unkempt fish tank will be more likely to have black algae problems as compared to a tank that is well-maintained.

Make sure to do regular water changes and clean the tank as often as necessary in order to keep black algae at bay.

Tip #5: Add Some Beneficial Algae

Adding some beneficial algae to your aquarium can help compete with the black algae for nutrients and space, leading to a decline in black algae populations.

There are many different types of beneficial algae, so be sure to do your research before adding any new species to your tank.

One type of beneficial algae that is known to be very effective is Caulerpa.

This alga is also known as “killer algae” because it will kill black algae over time.

So if you have a bad infestation of black algae then this may be your best option for how to get rid of black algae in a fish tank.

Is Black Algae In Fish Tanks Bad?

Black algae on the fish tank glass are unsightly and can be a nuisance, but it generally isn’t harmful to fish or humans.

However, if black algae become too rampant in your tank, they can compete with other plants and organisms for food and oxygen, potentially leading to their demise.

In extreme cases, black algae may release toxins and lower the water quality of your tank, causing fish stress and even death.

Black Algae On The Fish Tank Glass?

Fish tank glass catches a lot of attention when you have black algae on it.

It is very unattractive and looks like something out of a horror movie!

Most people don’t how to get rid of black algae from fish tank glass.

But there are several ways how to clean the aquarium glass without using chemicals that may harm your fish.

Here are some tips on how to get rid of black algae from fish tank glass:

Rubber Gloves – One of the easiest and most common is how to clean aquarium glass with your hands.

Just put on rubber gloves, lather up a little bit of dish soap onto them, and rub the surface gently.

Aquarium Glass Scrubber – If you don’t want to use your hands, you can buy an aquarium glass scrubber.

This is a small brush that has soft bristles and is specifically designed to clean the sides of an aquarium without scratching it.

Hot Water – Sometimes hot water is all you need to get rid of the black algae from the fish tank glass.

Just put a little bit of hot water on it and wipe with a dry towel, then rinse the whole surface clean with cold water.

Your Choice – In some cases, how to get rid of black algae from the fish tank is determined by your choice!

Will Black Algae Go Away On Its Own?

No, it will not go away on its own.

Black algae is one of the most common problems faced by fish tank owners.

Especially those who have a planted aquarium and want to grow live plants in their tanks as well.

If you do not take care of it at an early stage, black algae can spread quickly and become difficult to get rid of overtime.

How Much Time Will Black Algae Takes To Go?

The time required for black algae to go depends on how you are treating it.

You can surely remove it by hand or with a brush, but this may take some time and effort if the area is large.

To speed up the process of getting rid of black algae, use hydrogen peroxide in your tank.

It is considered the most effective way to get rid of black algae in a fish tank.

Using hydrogen peroxide may lead to some side effects, so you have to use it with caution.

Only add small amounts at a time and keep an eye on how your fish are reacting to this treatment.

Watch out for any changes in behavior or how they swim.

Another thing that you can do is to add some phosphate removers and chelated copper into your fish tank.

You should regularly monitor how the treatment of black algae in aquariums progresses, so you need to be able to easily check on how these affect water chemistry.

For example, using a liquid test kit for ammonia will help you monitor how the black algae are being affected by your treatment.

Remember that some treatments can be very harmful to fish and plants, so remember not to use too many of these products at a time.

Why Is The Gravel In My Fish Tank Turning Black?

The gravel in the tank also may be covered with black algae.

If the fish tank has gravel, it should be removed and replaced if almost completely covered in black algae.

If there is no gravel or sand on the bottom of your fish tank (e.g., an aquarium), you can still put some rocks at the bottom for decoration purposes but make sure they aren’t covered in black algae.

The probable reason for the gravel turning black is that dead organic matter (e.g., fish food, plant leaves, excreta) has not been removed regularly and thoroughly from the tank bottom, providing an ideal condition for the development of black algae.

What Causes Black Algae In a Planted Tank?

In a planted tank, the main cause of black algae is overfeeding.

This causes excess nutrients in the tank, promoting the growth of black algae and other forms of unwanted algae.

Planted tanks also tend to have more algae growth because of how plants utilize nutrients.

In planted tanks, the substrate is constantly being taken up by plants and distributed through their leaves.

Therefore, some black algae on aquarium glass may be a sign that your tank’s water chemistry needs adjusting or it could simply mean you need to start vacuuming the gravel more often.

There are also a number of other causes for black algae in planted fish tanks, including:

Poor water circulation.

Lack of light.

Excessively high or low pH levels.

Presence of dissolved organic matter (such as decaying leaves) in the water.

Improper tank maintenance (not cleaning filters regularly, not changing the water often enough, overfeeding).

Inadequate filtration (using a filter that isn’t powerful enough for the size of your tank or is dirty/clogged up with algae growth itself).

If you are having issues getting rid of black algae in fish tanks then changing how you care for it could help.

Some fish tank owners have found success with adding fast-growing aquarium plants like hornwort or hygrophila to the aquarium.

Additionally, you could try using beneficial bacteria products that contain nitrifying and photosynthetic bacterial species.

These will help break down excess nutrients into less harmful forms while promoting plant growth at the same time!

What Fish Will Eat Black Algae?

There are many fish that will eat black algae. Some of these include:

These fish will all scavenge algae off of surfaces in the tank, including black algae. They can be very helpful in keeping your tank clean and free of this type of algae.

Is Black Algae Harmful To Humans?

For humans, black algae are not harmful.

However, it can be annoying and unsightly to look at in your fish tank.

If you leave this alone for too long, the problem will probably spread and become more difficult to deal with later on down the road.

Humans can easily remove the algae by scrubbing it off with a sponge and some water.

It is also possible to use an algaecide or other products that contain clarifiers if you want something stronger.

But I’d recommend using caution as these chemicals can be harmful to fish so read any product label carefully before deciding how to proceed.

For the average fish keeper, however, just keeping the tank clean and free of organic buildup will usually be enough to discourage black algae from taking hold.

How To Prevent Black Algae In a Fish Tank?

To prevent black algae in the future after removing it from your aquarium, you should use the following steps:

Keep your tank clean by doing a water change and gravel vacuum every week.

Make sure to remove any excess food or organic matter from the tank that can lead to an algae bloom.

Use an algaecide on a regular basis to help control any algae growth in the tank.

Add some good quality plants to your tank to provide competition for the algae and help absorb any excess nutrients.

Regularly clean your filters to remove any organic matter that may be contributing to the algae growth.

Use a phosphate absorbing pad in your filter or hang it on the back of your tank to help control how much phosphates are entering the water.

Avoid using any lighting for more than six hours per day if possible, since algae thrive off the light and increased levels of phosphorous that is caused by too much light may promote black algal growth.

Black algae can be a frustrating problem to deal with, but using some of the preventative steps listed above should help you keep it from coming back in the future.

If you do see any signs of black algae starting to grow again, don’t hesitate to take action and remove it before it becomes too established.


In conclusion, there are several ways that you can get rid of black algae in your fish tank.

While some methods may be more effective than others, it is important to remember that patience and perseverance are key when trying to eliminate this pesky alga.

By following the tips provided in this article, you should be able to successfully get rid of black algae and return your fish tank to a beautiful, clean state.

If you have any questions or concerns about how to get rid of black algae in fish tanks, please leave us a comment below and we will be happy to assist!

Also, let us know some additional tips that we may have overlooked that will help others get rid of black algae in fish tanks!

Comment below!

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