Black Fish That Eats Algae (Best Black Beard Algae Eaters)

Interested in black fish that eats algae? This guide is for you!

A good number of fish keepers have to contend with the problem of algae, more so because only a few aquarium species eat these aquatic, non-flowering plants.

In fish-keeping, the biggest headache is caused by the black beard algae species.

This algae species thrive best in dirty and poorly maintained tanks because of the tanks’ high level of phosphates and nitrates.

Apart from keeping your tank clean, it would be best to consider keeping black beard algae eaters to prevent the algae from thriving.

The best black beard algae eaters are Chinese algae eaters, Florida flag fish, Siamese algae eaters, Otocinclus Catfish, and the Flying foxes. Other fish that do a considerably good job include Clown plecos, Bristle Nose plecos, Goodeids, and Golden algae eaters.

Though they are not fish, Nitrite snails, Cherry Shrimp, and Amano Shrimp are also good at keeping the black beard algae in check.

Otocinclus algae eater

What is Black Beard Algae?

Black beard algae are simple, aquatic, non-flowing plants usually referred to as BBA. They are scientifically referred to as Audouinella sp.

If your fish tank has been invaded by algae, it’s most likely that this type of algae belongs to the BBA species, which is part of the red algae family.

In some circles, you’ll hear these algae referred to as black brush algae or brush algae.

Black beard algae can grow on any surface in the fish tank. However, they commonly attach themselves to the leaves of aquarium plants.

The name black beard comes from the fact that this alga grows in tufts of dense patches that resemble a beard.

BBA comes in various colors, from blackish green to bright green. However, the most common type presents itself in black coloration.

The delicate strands of black beard algae are fast-growing. If left unchecked, they soon dominate the entire aquarium and make life difficult for the fish and plants therein.

Although BBA does not release any poisons, it creates an imbalance in the aquarium, thus stifling life for every other living organism in the water.

Its modus operandi is to cover plants entirely, making them unable to absorb light that’s much-needed for the process of photosynthesis.

The good news is that the menace of BBA is easy to solve if you arrest it in good time.

What Cause Black Beard Algae?

To better protect your fish and aquarium plants from the BBA menace, you should understand what causes it.

This will put you in an excellent position to take preventive measures before the problem goes overboard.

Too Much Light in the Tank

This is one of the major causes of BBA. Although aquarium plants need light for growth and photosynthesis, an over-supply of light encourages the growth of BBA.

Poor Water Quality

Black beard algae are likely to grow in a tank with dirty water. This is one of the significant reasons you should regularly change the water in the tank.

It is recommended that you should change about 25% of the water weekly. Also, ensure you install a proper filtration system in your fish tank.

Poorly filtered fish tanks are likely to have an outbreak of BBA.

Unstable CO2 Levels

The plants in your aquarium depend on reasonably high levels of carbon dioxide in the water to absorb nutrients.

The recommended level of CO2 in the aquarium is around 15-25 mg/L. you can increase the CO2 level manually or use fast-growing, floating plants such as anacharis and hornwort.

If the CO2 levels are too low or unstable, the conditions become ideal for the growth of BBA. Under such conditions, the aquarium plants will not be able to compete favorably with the algae.

Additionally, you can stabilize the CO2 levels by providing a steady flow of clean water.

High Levels of Phosphates and Nitrates

BBA thrives very fast in a high nitrate, high phosphate fish tank. This is because these algae need nitrates and phosphates to grow.

These are some of the basic nutrients that algae feed on. As such, reducing phosphates and nitrates in the water makes it hard for BBA to thrive.

What Are the Best Black Fish Algae Eaters?

#1 – Siamese Algae Eater

Siamese algae eaters have made a name for themselves for their ability to burst black beard algae. Many keepers prefer this species of fish because of its ability to keep the tank clean and free of pests.

Also, this fish adds beauty and color to the aquarium with its black or brown coloration and radiant white stripe at the back.

#2 – Bristle Nose Pleco

Bristle Nose Plecos will clean the tank of all algae within a considerably short time. These aggressive fish can grow to about 5 inches long.

If you are to keep this species to help you clean the tank, consider that they need plenty of hiding spots.

You also have to be careful about the choice of tank mates for this fish, because it tends to be aggressive.

#3 – Clown Plecos

This is another member of the pleco family that is quite adept at cleaning the aquarium of black beard algae and other unwanted organic matter.

The Clown Pleco can grow up to 3 inches long. Also, it is a docile, friendly fish that lives well with a wide variety of tank mates.

#4 – Flying Fox Fish

This freshwater fish species measures not more than ½ an inch in length. The Flying Fox fish takes on all types of algae and bacteria.

As such, it is a welcome addition to your aquarium if you’ve been having trouble with BBA and other disease-causing organisms.

The Flying Fix Fish can be found in nature in streams, ponds, and lakes. This fish lives well in captivity, especially if the living conditions are favorable.

#5 – Florida Flag Fish

This freshwater black beard algae eater is commonly found in the state of Florida in the US. Its silver coloration and black stripe at the back make it aesthetically appealing in the fish tank.

The Florida Flag Fish grows to a length of about 2.5 inches, and can be found in most water bodies in the wild – including ponds, rivers, and lakes.

#6 – Chinese Algae Eaters

This peaceful, friendly, and docile species is used in many parts of the water to clean tanks of algae. It is a small, easy-to-care-for fish that originally came from China.

#7 – Otocinclus Catfish

This small, peaceful, and docile fish can fit perfectly n a community tank where they will quietly embark on devouring the BBA.

Also, they are easy to keep because they eat any type of food. Therefore, the Otocinclus Catfish is ideal for a beginner keeper.

#8 – Amano Shrimp

This tiny, bright-colored crustacean can live in the aquarium for years, cleaning it of algae and other unwanted organic elements.

Because of its small size, the Amano Shrimp is ideal for eating microalgae and bacteria.

#9 – Cherry Shrimp

The Cherry Shrimp has grown popular as a great black beard algae buster.

This shrimp is a hardy creature that can live in the aquarium for years, cleaning it and keeping it free of unwanted elements.

The Cherry Shrimp can grow up to 2 inches long. This makes it ideal for eating microalgae and algae that attach themselves to rocks.

#10 – Ghost Shrimp

The Ghost Shrimp is tiny and grows to about 1½ inches in length. This green and red creature love eating all types of algae.

It is a welcome addition to your tank if you hope to get rid of black beard algae.

#11 – Nerite Snails

These green-colored, black-shelled snails are found all over the world. However, they are most common in the US.

It is here that they were first used as tank cleaners. Today, Nerite snails are used worldwide to clean BBA tanks and other algae.

Is Black Beard Algae Toxic to Fish?

Black beard algae do not actually produce any toxins. So although these aquatic non-flowing plants may be unsightly, they do not directly harm your fish.

Actually, a good number of fish species enjoy eating black beard algae. Like most algae, the BBA has high levels of carotenoids, which improve the health and color of your fish.

BBA can also help fish battle certain types of health conditions. For example, research has shown that this alga is particularly good in helping fish deal with stomach inflammation.

However, this is not to say that BBA should be entertained in your fish tank. On the contrary, the presence of BBA brings more harm than good to the aquarium.

These algae cause harm by stifling the life of plants. So when plants die, you can be sure that your fish and other valuable organisms in the tank are in danger.

At the same time, black beard algae make rocks, plants, and other décor used in the fish tank look unsightly.

BBA is also known to clog filters and power head intakes. Clogging filters make the water dirty, which is a health hazard for the fish.

When the power head intakes are clogged, the water pump may overheat and cause a mishap. As such, there’s every reason to keep black beard algae under control.

These algae should never be allowed to dominate the fish tank.

How to Eliminate Black Beard Algae

Look for the Source of the BBA

What is the cause of the black beard algae in your fish tank? Earlier, we discussed some of the most common causes of BBA in fish tanks.

Knowing the source of the black beard will inform you on how best to deal with it.

Remove the Black Beard Algae Manually

This should be among the very first things to do, especially if your fish are averse to tank mates. Next, you can use a soft brush to gently remove the algae from leaves, rocks, and tank surfaces.

Be careful not to damage anything as you go about this.

Add a Black Beard Eaters to the Tank

This is a very effective way of removing black beard algae, and preventing them from growing. Some fish species (like those covered in this post), snails, and shrimp are very good at this.

Not all fish or invertebrates eat algae. Also, some are picky about the type of algae they eat.

As such, ensure that you introduce fish or invertebrates that will eat the black beard algae if you hope for the problem to disappear.

Infuse CO2 (Carbon Dioxide) into the Tank

As noted earlier, one of the major causes of black beard algae is low CO2 levels. You can correct this by injecting CO2 into the tank using a pressure system.

A DIY yeast system is also recommended. However, some keepers prefer to use liquid carbon to boost the CO2 levels in the tank.

Use Chemical Controls

The use of chemicals to control BBA should be done when the problem is severe.

However, chemicals should be avoided if the problem can be solved manually, through the use of BBA eaters, or any other viable way.

If you choose to use chemicals, carefully read and follow the manufacturer’s instructions. This is because the inappropriate use of chemicals can harm your fish and other life forms in the fish tank.

One of the most commonly used chemicals to control BBA is a 3% hydrogen bath.

How to Use Chemicals to Control Black Beard Algae

There are a number of things you need to consider when using chemicals to control algae.

Water Volume in the Tank

If you are using a small tank for your fish, you need to understand that its ecosystem is fragile. This means you should use small doses as per the manufacturer’s recommendation.

The volume of the water in the tank dictates how many chemicals you can add.

Type of Plants in the Tank

You’d want to protect the aquarium plants in the tank from overdosing on the chemicals you intend to use.

As such, don’t use high doses if you only have a few plants in the tank. Also, consider the type of plants – some plants are more tolerant to chemicals than others.

Fish Tank Lighting

Black beard algae grow fast when the fish tank is exposed to a lot of light. To control this high growth rate, ensure that lights are not on 24/7.

It is recommended that you don’t keep lights on for more than 10 hours daily. Otherwise, the black beard algae will grow even when you use chemicals.

How to Prevent BBA from Returning

The best way to deal with black beard algae is to control it before it overwhelms the plants in your tank.

First, you need to get rid of any signs of BBA. Then, once you have achieved this, take measures to keep this menace from returning.

Here’s how to go about it.

Keep the Aquarium Clean

Black beard algae are not likely to grow in a clean tank. But, on the other hand, a dirty, unkempt tank is the perfect breeding ground for these algae.

Dirt and grime provide BBA with the nutrients to grow and thrive.

Keep the tank clean by changing at least 25% of the water weekly. Also, make it a point to regularly vacuum clean the gravel and substrate.

Do not allow food leftovers and decaying organic matter to remain in the fish tank.

Control the Amount of Light in the Tank

Black beard algae will likely grow out of control when the aquarium has too much light. As such, it is in your interest to control the amount of light coming into the fish tank.

Make it a point not to allow more than 10 hours of light daily into the tank. Most of the time, 8 hours of light per day is adequate.

Controlling light into the tank has become easier because of smart timers that control light. Some of these work using Wi-Fi or Bluetooth.

If you plan to invest in one of these gadgets, ensure you source it from reputable dealers. A good-quality timer will serve you well should you forget to switch the light on or off.

Use Phosphate Neutralizers

Black beard algae thrive in the presence of nitrates and phosphates. Therefore, to stem the growth of BBA and stop them from returning, you should deal with the phosphate and nitrates in the water.

The best way to do this is to use credible and high-quality phosphate and nitrate neutralizers.

These products remove these elements and stop them from recurring, thus stifling the growth and BBA.

Regularly Test the Tank Water

You should always be aware of what the water parameters look like. You can achieve this by regularly testing the water.

In particular, test for substances that promote the presence of growth of BBA. This will inform you when to take action to prevent the black beard algae from recurring in the tank.

Encourage the Presence of Beneficial Bacteria

Having enough beneficial bacteria in the tank is suitable for your fish and plants. These bacteria detect and get rid of any unwanted elements in the tank.

For example, some bacteria dig out and use food leftovers and other organic materials. This denies the black beard bacteria and other harmful pathogens from thriving.


Black beard algae eaters are a great addition to your aquarium. They will keep your fish company, and you’ll discover they don’t cost a fortune.

Also, black beard fish eaters are small and easy to care for. They are readily available in live and online pet stores.

The best thing about black beard algae eaters is that they will keep your tank free of the BBA menace.

A good number of these little guys will also help you eliminate other forms of harmful organisms, such as disease-causing bacteria.

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