Black Algae present in fish tanks possess some complex phenomena of adaptation. Their single-sided morphological appearance earned them the name, Black Beard Algae (BBA) and Brush Algae.

Black Algae are typically opportunistic organisms that can infest your tanks. They significantly increase the amount of intensive cleaning tasks required for your tanks.

Though BBAs’ are hardy organisms to eliminate, they are not invincible. Over the years, many practices have been tried and tested; how to prevent, control, and eliminate them from aquariums.

Let us learn about their causes and, most importantly, get acquainted with some simple methods to tackle them.

What is Black Algae?

They are another form of Red Algae that occurs in an unbalanced ecosystem. A Black Algae will turn red if immersed in an alcohol solution. Naturally, Algae spores are present in almost all environments.

They become prominent in a humid environment that promotes their growth. The type of Algae that appears in your tanks may be an indicator of water quality.

Usually, the presence of Green Algae is considered a sign of a healthy ecosystem. On the other hand, the occurrence of Black Algae indicates an unbalanced one.

Can You Spot or Identify Them?

BBA or Brush Algae are morphologically similar to the name given to them. They can grow on almost any surface in tanks.

In routine occurrences, they are seen on the leeward side of the substrate that is away from the water circulation area. For example, a large rock on the opposite side of filtration.

In planted tanks, they can grow on leaves of slow-growing plants such as Anubias, Ferns, Cryptocoryns, etc. They can sometimes expand over the shells of snails.

The dark coloration of its pigment gives an unpleasant and nasty sight to tanks. Any medium-to-pro aquarist may be able to identify them with ease.

Warning Signs of Black Brush Algae in Tanks

BBAs don’t just appear in a tank overnight. Once the environment becomes favorable, they can start mutating to a stronger type (the black form).

Initially, the normal inhabitants (appearing light green) will start to gain darker greenish shades before taking the devilish dark form.

For someone with keen eyes, this observation can be taken as a warning sign to start correcting the flaws in tank parameters.

Which Type of Tank is More Susceptible to BBA Outbreak- Freshwater or Saltwater?

In nature, Red Algae (or BBA) is more abundantly found in saltwater. Distribution data indicates that only about 5% (estimated at 1500-5000)  are found in freshwater.

Strictly based on figures, the perception that they occur more in saltwater can be wrong. Freshwater accounts for only about 3% of the earth’s water, so the numbers are still huge.

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In an aquarium, both types of tanks can provide an equally suitable ecosystem for its occurrence as they are ‘everywhere’, remember?

Major and Minor Causes for Black Algae in Fish Tank.

The outbreak of BBA in a tank has several causes. Many hobbyists encountering these issues have different views and experiences. Let us take a look at most of them.

Major Causes

  • Excess Lighting: Algae are classified as plants. It can undergo photosynthesis in the presence of light to produce food. Most BBA-infested tanks have access to more intense lighting intensity and frequency.
  • Low CO2 Supply: The amount of CO2 in a tank is important for a planted tank. BBA thrives more aggressively in CO2 deficient water. Plants also lose their immunity when stressed with lower CO2.

The battle for survival between green plants and black algae for limited CO2 gives BBA an upper hand because it can utilize hydrogen carbonate ions present in water.

  • High Nutrition: Nutrient-like substances such as nitrite, ammonia, nitrate, and phosphates are the primary compound for algae to utilize.

These substances are abundantly present in over-fertilized and over-fed tanks. Along with it, decaying plants, and animal excreta can provide a conducive environment for BBA to flourish.

  • Filtration: In an effective filtration system, water is continuously circulated in every part of the tank. However, lack of flow in any part of the tank can be a breeding place for algae.
  • Unintentional Introduction: When introducing new organisms or even from the new tank substrates, BBA can find entry into the tanks.
  • Water containing higher levels of iron is known to trigger BBA invasions in tanks.

Minor Causes

  • Tank Overload: Overcrowded tanks are prone to accumulating waste material. Even with maximum filtration systems, the bio-load can be too elevated for proper purification of the system.
  • Impurities: Water containing higher levels of iron is known to trigger BBA invasion in tanks.
  • Temperature: Algae grows well in warmer water compared to a cooler temperature.
  • Fluctuating CO2 Level: Non-consistent supply of CO2 in water can be another reason for planted tanks.

Control Methods for Black Algae in an Aquarium

It would be inaccurate to claim that BBA can be removed from the tank with a simple trick. Their biological structure is quite sturdy enough to even scrub them away manually.

A combination of different methodologies can be applied for the most effective results. Good care of the tank parameters is requisite to prevent re-occurrence.

Natural Methods

These methods can seem virtually simple, yes, they are! But, it requires effort and patience.

Manual Removal of BBA on Inanimate Object

Algae growth on glasses can be scrubbed away conveniently using a kitchen scrubber.

One might have to chip away some layers of driftwood. A hard plastic brush can be used on rock surfaces.

Manual Removal of BBA on Plants

Trying to remove BBA from the leaves of plants can be a futile approach. However, there is nothing wrong with cutting off the affected part of the plants as they can always regrow.


There are several kinds of fishes and crustaceans that love a good algal meal. Though Black Algae aren’t the most appetizing, they are a good source of nutrients.

The tank environmental parameters should match up with the fish or crustaceans before introducing them.

  • Fishes
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Siamese Algae Eater fishes are well-known for their BBA eating habits. Younger ones are preferred for such purposes, as adults can grow huge.

Another less commonly talked about species of fish with a decent capacity to control algae is the Plecos, Hill Stream Loach, and Molly fish.

  • Snails

The Clinton Corona and Nerite Snails are in the good books of algae-eating species. Their excessive egg-laying capacity can be the only downside. Otherwise, these organisms are great choices.

  • Shrimps

Shrimps are natural predators of algae. They can just overwhelm your tanks and algae with their numbers. Amano Shrimp are preferred for BBA issues.

Note# In the presence of a more palatable (chewable) type of algae, especially Green Algae, BBA may escape predation without suitable chemical treatment.

Chemical Procedure

These methods can show moderately good results but can also be life-threatening for innocent inmates if used without the proper direction of the chemicals.

Common Disinfectants

Using some commonly available disinfectants such as calcium hypochlorite (bleaching powder) and hydrogen peroxide on infected objects can aid in their easy removal.

These chemicals weaken the spores and cell walls of BBA. 3% hydrogen peroxide is preferred over other concentrations. These chemicals should only be used in mild doses.

The residual leftovers should be properly cleaned and rinsed after treatment.

Commercial Algaecide

These chemicals are relatively safe for tanks as they are specifically designed for such purposes. Most of them involve spraying or dropping chemicals directly on the affected area.

A good list of them can be procured from an aquarium store or online. The dosage and labels should be read properly before use. Algaecide-treated Black Algae are preyed upon by predators.

Artificial CO2 Supply

A low level of carbon dioxide in the tank increases the survival of Brush Algae. Likewise, providing a higher quantity of CO2 can do just the opposite.

Commercial CO2 pumps are available for aquarium use. Obtaining a CO2 device for a non-planted tank may not be a cost-effective solution.

Other viable options for economical CO2 supply include liquid carbon supplements for occasional use.

Liquid Carbon Supply

Commercially available liquid carbon is simple to apply to tanks just like any other fertilizers for plants. These products are like multi-vitamins for plants.

Once an ample amount of carbon for plants is available, they can develop immunity against algal bloom on their parts.

The determination of the dosages is in the direction of its label, according to the company’s manufacturing standards.

Precautions During Removal of Black Algae

  • When removing BBAs’ from plants, it is better to transfer the entire plant out of the tank first. This can prevent algal spores from getting into the tanks. The same trick applies to any other substrates.
  • Wash the plants or substrate with purified water for plants and disinfectants for objects/substrates before refitting into the tanks.
  • In instances where you have to remove BBAs’ from the shells of snails, avoid using acidic chemicals at all costs. The shells of crustaceans are vulnerable to acid pH (1.0-6.5).
  • It is advisable to do a 100% water change in tanks after an algal removal procedure.
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Best Care Practices Against BBAs’

All the other steps that we have discussed can be rendered ineffective without proper routine management practice. Black Beard Algae loves to revisit old tanks!

These steps can be followed to prevent, eliminate, and protect your tanks from BBA invasion.

  • Lighting Control: Light is essentially required for planted tanks for a maximum duration of 8 hours. Providing more light periods can only attract algae. For non-planted tanks, blue LED lighting is a better option.
  • Plant Choices: Unless you are desperate to own slow-growing plants, fast-growing plants can save you the trouble from Black Algae to some extent.
  • Proper Aqua scaping: The arrangement of the tank substrate and plants should be done in such a way that the water circulation is unobstructed.
  • Feeding Control: The maintenance level supply of food and fertilizer is good enough to keep your aquarium healthy and running. Over-fed plants and animals do more harm than good.
  • Optimum CO2:Obtaining a CO2 regulator can ensure a stable supply of bubbles per second of carbon dioxide.
  • Water Quality: Purified water is necessary for aquariums. A regular water change of 20-50% per week is a standard approach to maintain its quality.

The nitrite, nitrates, and ammonia concentration should be negligible in tanks.

  • Inmate Population: The number of species should be kept minimal to avoid the cascading effect of metabolites and leftover feeds. Overcrowded animals and plants are more prone to stress- a perfect recipe for algal invasion of plants.
  • Temperature Control: Setting up your water temperature on the lower side of the inmate’s requirement can slow down the growth of algae.
  • Quarantine: New inmates should be quarantined for 3-7 days before putting them in established tanks. Disinfecting non-living objects/substrates can prevent unexpected outbreaks.

Frequently Asked Questions

Does Light Cause Black Algae in Fish Tank?

Yes, light is a factor responsible for the growth of Black Algae. An optimum presence of light will keep them green, while excessive supply will allow them to mutate faster.

It would also be incorrect to say that light alone is responsible, as we have come across several other factors that can mutate them.

What Eats Black Beard Algae?

Any small fish or crustaceans that are herbivores or omnivores can consume them. If they eat it in the first instance, factors like accessibility and alternatives will play a role.

Species like Siamese Algae Eater fish and Amano shrimps are fond of BBAs’.

Are All the Black Spots in Tanks Related to Algae?

No, though most black spots can be attributed to algae, it would be analytically wrong to conclude it. Think of a probability where you splashed a tiny drop of black paint on the glass!

Is Any Homemade Algae Remover Work?

Yes, any alcohol-based solution can do the trick, but they are not practicable in a live tank. Common bleaching powders are used by many keepers.

In Conclusion

Black Algae are indeed a thorn for hobbyists. Despite being a pest to the tanks, they shouldn’t be a deterrent to the hobby.

On a positive note, its occurrences in tanks should be taken as a useful aid for raising the sustainability index of the tank.

Ultimately, the successful prevention of its outbreak can elevate you to the level of perfection.

About the Author

Dr. Vituotsolie Kiso

Vituo Kiso is a budding Veterinarian and marine species enthusiast. He did most of his internships in several Pet Clinics, Wildlife centers, and Farms across India. He has a passion for learning new things and writings besides giving consultations and treating pets.

Career Highlights:

  • Almost 3 years of experience as a Veterinary Practitioner
  • Online Pet Health Consultant
  • Verified Tutor

Educational Highlights:

  • Attended Rajiv Gandhi Institute of Veterinary Education and Research
  • Currently learning Geography, History, Polity, Economics, Ethics, and International Relations.

Writing Experience

  • Wrote a White Paper on ‘The Aura of Pets and Humans’ for MaxCare Pets Inc.
  • Awarded the Best Article Writing on World Environmental Day 2020 on the topic, ‘Biodiversity.’

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