Brown Algae In Fish Tank | How TO Get Rid Of Brown Algae

Brown algae in a fish tank is a sign of the process of establishing biological balance. However, their rapid growth signals negative changes in the fish habitat. The problem can arise from a lack of higher plants, poor aeration, and filtration accumulation of uneaten food particles. If brown plaque appears on glass and aquatic plants, action must be taken immediately. Getting rid of diatoms is easy, but you need to know how to treat your aquarium.

Brown Algae In Fish Tank

Brown algae – What Is It?

Brown algae are microorganisms that can exist both singly and in colonies. They are also called diatoms (that is, split in two) algae. This name is given because the individual consists of two parts: the upper half of the shell – pithecus, and the lower half – hypotheca.

The causative agent of the disease multiplies by division. The mother gives the daughter part of the shell. The second part of the shell forms after a few hours.

Individuals are capable of forming colonies that look like brown bushes with tubular constituents. Bushes grow quickly, reaching a height of 20 cm. But more often they spread in width, forming a plaque on plants and other captured surfaces. By quickly filling the aquarium environment, diatoms do not allow higher plants to fully grow and develop.

brown algae

The Most Common Species Both In Nature And At Home Are:

  • Navicula. The most widespread and numerous species, including more than 10 thousand subspecies. The specimen under the microscope looks like an oval with pointed edges, resembling an ash leaf or a boat when viewed from above. To move, it synthesizes mucus, on which it slides. The species inhabits not only water bodies, it can live in soil and even in rocks. Active reproduction is observed in the warm season of the year, during the same period there is a high probability of damage to the aquarium.
  • Pinnularia. Inhabits the bottom of water bodies, actively moves among the bottom silt. The specimen is divided into two parts, between which there is a core. Cell division occurs every 5 days. Active reproduction is observed in summer and autumn.
  • Cymbella. It has many subspecies. The specimen looks like an elongated oval. Most of the time lies motionless on the bottom, moves only in search of food. Active reproduction takes place during the summer months.

Related : How To Get Rid Of A Black Beard Algae In An Aquarium? | Tips & Tricks

The Reasons For The Appearance of Brown Algae In Fish Tank

When setting up a new aquarium, it is normal for brown formations to appear on the walls and in the water. In this case, the reason is the uninhabited environment. The bio balance is just being formed, higher plants and fish have not yet had time to absorb carbon and organic particles in the water. When the biological equilibrium is established, the diatoms will disappear on their own.

But if the aquarium is inhabited, and brown “mold” suddenly began to appear in it, then you need to take action. Of the most likely causes of the disease, the following should be named:

  • Insufficient lighting of the aquarium (brown microalgae – partial shade lovers)
  • Increasing the concentration of iodine in water
  • The saturation of water with silicates used by algae for nutrition (perhaps there is an abundance of silicon in the aquarium soil)
  • Overfeeding fish (the remains of food settle on the ground, rot, saturate the water in excess with organic elements suitable for feeding algae)
  • Overpopulation (fish emit so much waste that beneficial bacteria do not have time to process nitrates and nitrites, and the environment becomes favorable for the reproduction of diatom microalgae)
  • Too thorough cleaning of the aquarium (if at the same time treat the soil with a siphon, clean the filter, change a significant volume of water, then the number of beneficial microorganisms that process fish waste will be greatly reduced).


The first sign of damage by diatoms is the appearance of a brown finely dispersed plaque on aquarium glass, on stones, soil, and leaf plates of aquatic plants. The plaque quickly thickens and darkens. The aquarium takes on an unattractive, unkempt look. The water becomes cloudy, brownish.

Brown microalgae enter the aquarium with planted plants, fish, and contaminated decorative items.

The Reasons For The Appearance of Brown Algae In Fish Tank

How To Get Rid Of Brown Algae?

If the symptoms of infection appear in a new, recently inhabited aquarium, then there is no need to worry. It is enough to follow the rules for keeping the aquarium and caring for the fish, and the concentration of algae will return to normal after about two weeks. The owner must clean the container regularly, changing 20% ​​of the water every week. When higher plants take root and start active life, they will displace their unicellular neighbors.

If a noticeable plaque has formed in the new aquarium, it is removed mechanically from all surfaces. Use a toothbrush, hard sponge, scraper, or anything with a blade.

How To Deal With Brown Bloom In A Habitable Aquarium:

  1. Increase water change by 20% up to 2 times a week.
  2. At each change of water, clean all elements: glass, plant leaves, decor details.
  3. Check the filter for filtering activity. If the device clogs, it becomes weaker, then you need to clean it.
  4. During the fight against pathology (for a day or two), the duration of lighting should be reduced to 6 hours a day. Then gradually bring up to 10 hours a day within 2 weeks. It is advisable to replace old lamps with new ones, but not all at once, but in turn.
  5. Into the common aquarium, let the inhabitants feed on microalgae. We recommend purchasing otocinclus catfish, gyrinocheilus, and plecostomus catfish, theodoxus snails.

Methods for getting rid of brown algae in fish tank are simple, the fight takes an average of 3 weeks.

What is undesirable to do is to fight diatoms with chemicals. Medicines are ineffective against algae, but they inhibit the development of beneficial microorganisms, which makes the situation worse. As a last resort, you can try the antibiotics “Penicillin”, “Bicillin”. If the problem is caused by a lack of vegetation, then you can add a medicine from the group of algicides to the water, but in a prophylactic dose.

How To Get Rid Of Brown Algae


To Prevent The Reproduction Of Diatoms, It Is Necessary:

  • Use lighting devices of the red spectrum
  • Change water weekly
  • Prevent contamination of the aquarium, thoroughly clean it every two months
  • Install high-quality filtration and aeration devices in the aquarium
  • Plant a sufficient number of aquatic plants
  • Control the concentration of iodine, silicates, nitrogenous compounds in water.

If these guidelines are followed, the aquarium will remain healthy and attractive.

Leave a Comment