If algae develop in the aquarium, it can have various causes and be due to a certain type of algae. They multiply quickly and swift action is recommended, because many attempts to remove algae usually fail, especially at an advanced stage. With the following tips it works and with certain measures a new infestation can be prevented.


Every type of algae arises because there is a biological imbalance in the aquarium. The most common reason is that the nutrient content is too high, with nitrite and phosphate in particular promoting the formation of algae. This is mainly due to well-fed fish, which accordingly produce more excretions in the water. In addition, fish food lying on the bottom increases the nutrient content.

Other factors favor the increase in nutrients and thus the formation of various types of algae:

  • Dead plants in the aquarium
  • No regular water changes
  • Fish carcasses remaining in the water for a longer period of time
  • Too much tap water, which brings phosphate into the pool and increases the content accordingly

Home Remedies vs. Artificial Anti-Algae Remedies

Artificial / chemical anti-algae agents are generally available or for a specific type of algae. These include effective means. The core problem, however, is that they do not restore the natural biological balance, but can even impair it.

In other words: with artificial / chemical anti-algae products the cause is not eliminated, but only solved the problem for a short time. If the effect of the agent wears off, algae form again.

Using suitable home remedies, on the other hand, the natural, biological balance can be restored. In connection with preventive measures, algae can be kept out of an aquarium in this way in the long term.

Grünalgen (Chlorophyceae)

Green algae are among the best-known types of algae and can be easily recognized by the green, long-thread structures that attach to the plants. They can be identified by green, mushroom-like coatings on panes and objects such as stones. They form due to a high excess of nutrients in the water.

First of all, the infestation must be contained by cleaning the green algae from panes, stones and other accessible elements in the aquarium.

As a home remedy, the use of certain fish has proven to be an effective “weapon” against algae. They feed on green algae, reliably remove the infestation and prevent a new infestation.

When choosing suitable fish, it should be taken into account that not everyone is suitable for removing algae due to their size or their behavior towards other aquarium fish. In addition, manual feeding should be reduced so that the fish cannot eat their fill of the fish food, otherwise they will no longer ingest any algae.

Fish that can be used include:

  • Honeycomb sign catfish (Glyptoperichthys gibbiceps) – due to its enormous length, only suitable for extremely large aquariums
  • Blue catfish (Ancistrus dolichopterus) – size between ten and 15 centimeters
  • Siamese algae (Crossocheilus oblongus) – an aquarium fish about 16 centimeters long – gets along well with other fish
Tip: Siamese trunk barbs should be kept in groups of 4 or 5, because then they feel most comfortable and develop corresponding hunger. However, the aquarium should be at least 120 centimeters long.

Blue-green algae

If blue-green algae form, this is a clear indication of poor water quality. This develops mainly due to excessively high nitrite and nitrate levels. The blue color cannot always be easily distinguished from green algae, but slimy coatings on stones, plants and other aquarium contents. They are a stubborn type of algae that also settle on filter materials and can greatly reduce the filter properties.

In order to master the rapidly growing blue algae infestation, these should be sucked off with a suction device. Technical products such as filter systems and oxygen pumps must be thoroughly removed from them by hand, since in the worst case, they can impair the trouble-free functionality.

As with green algae, the use of certain fish / aquatic animals is the best method for removing blue algae. Here, too, it is important to drastically reduce or stop feeding fish feed so that they have to feed on the algae. Aquarium fish can easily get by for a week without feeding.

Suitable aquatic animals for use against blue-green algae include:

  • Suckwelse
  • Various types of snails, such as limpets (Neritina pulligera) or antler snail (Clithon sp.)


Beard algae come from the red algae family and can be recognized by their hairs, which are reminiscent of whiskers. They are mainly to be found on filter systems, decorations and the aquatic plants. The causes usually lie in an excess of nutrients or a lack of nutrients.

Bearded algae is a very robust type of algae that can be removed in the conventional way. If the filter outlet is infested, the direction of flow must be changed so that the algae loosen. If necessary, help must be given by hand. Infected parts of the plant are to be separated. If there is a strong infestation of plants, it is advisable to dispose of them from the aquarium. Beard algae can be removed from decorations mechanically, cleaned thoroughly and put back in the pool.

Brush algae

The brush algae, like the bearded algae, belong to the family of red algae. This type of algae prefers corner and edge areas as well as areas where the current is relatively strong. They can quickly become a nuisance and are therefore the most feared type of algae in the aquarium and should be removed as soon as possible.

They show up as dark green to black colored tufted algae. The causes of an infestation can be found in too many nutrients and a simultaneous lack of CO2.

It is difficult to select the tufted algae on plants, so the only way to remove them is to remove them from the aquarium together with the infested plants. The gravel should be vacuumed thoroughly and special fish will feed on the leftover algae as well as being useful in preventing re-infestation. In addition, the flow must be reduced, which also reduces the risk of a new infestation.

The following fish feed on brush algae, among others:

  • Barbel (Barbus barbus) – species of carp that is only suitable as a young fish for aquariums
  • Black Molly (Poecilia sphenops) – aquarium fish with a length of six to seven centimeters
  • Guppy (Poecilia reticulata) – freshwater ornamental fish with a maximum length of 6.5 centimeters


Diatoms are often referred to as brown algae due to their brown color, but they only occur in the sea. A greasy coating on the substrate, decorations and other objects, and especially on plants, is the result of this type of algae. Often there are also oxygen vesicles, which are caused by photosynthesis.

The causes of diatoms are usually a lack of light and poor water quality, whereby water that is too hard can be responsible for an infestation due to an excess of carbonate.

Diatoms can be removed quite easily with the aquarium vacuum cleaner. At the same time, infested parts in the aquarium should be prepared by them by hand. Once the algae have been removed, at least a third of the aquarium water should be replaced with softer water. In this way, the total carbonate content in the aquarium can be reduced.

As an alternative to “hand cleaning”, armored catfish can also be used to remove algae. They are available in the dwarf version with a size of up to four centimeters. The medium-sized specimens are between twelve and 15 centimeters long. The giant fish with a length of up to one meter are not suitable for aquariums.


Thread algae are categorized into the group of green algae. They form when there is an excess of nutrients in combination with excessive lighting. They should be removed quickly, as they can overgrow the entire aquarium in a very short time, entangling plants in particular and thereby often killing them. They are often found in groups at the roots of the plants, where they can reach a length of up to 20 centimeters.

The thread algae can usually be easily removed by hand. Some shrimp, such as the Amano shrimp, feed on them and ensure that they do not form again or prevent them from spreading unless they are oversaturated with shrimp food.

General prevention

size The aquarium size has a major influence on whether algae form quickly or less quickly. In general, it can be said that larger pools are less prone to algae formation than smaller ones. However, this is of course primarily dependent on the number / stocking of fish and plants. The fuller a tank, the higher the risk of algae. Experts recommend newcomers to a tank size of around 100 liters and, if necessary, slowly increasing the number of undemanding fish so that sufficient experience can be gained for more difficult-to-keep fish in larger tanks.

Choosing a location
Sun generally favors the formation of most algae. With diatoms it is exactly the other way around. They mainly develop in shady places. For this reason, a location in partial shade, such as on a wall opposite a south-facing window, is ideal. As a guideline: at least ten hours of brightness and in no case more than twelve hours. Alternatively, of course, artificial lighting can also be used. The recommended exposure time also applies to these.

Water quality
The water quality should be tested regularly. The pH value, carbonate content and total hardness as well as the proportions of nutrients in the water can be determined with the help of simple test sets. These are available from specialist dealers.

Filter system
, a filter system is basically based on the number of fish / size and the general stocking with decorations and plants dependent. Especially in small pools there is a risk of overcrowding, so that natural self-cleaning and the biological equilibrium in general become unbalanced. For example, fish droppings can accumulate, toxic substances develop from them and lead to serious problems in addition to algae infestation. Here it is important that a powerful filter is chosen.

Tip: It is ideal if two filter systems are used that absorb coarse and fine dirt particles.

Ground gravel
A fundamental prevention through the right choice of floor covering is not possible because the different types of algae have different “preferences”. For example, the blue-green algae likes light gravel. If the floor is laid with dark gravel, however, the chance of blue algae infestation is reduced.Plants
Plants and algae are direct competitors for nutritional needs. Fast-growing plants, which usually have a high need for nutrients, are ideal for preventing algae. In this way, the algae can be deprived of any education and livelihood. In order to keep the balance at an optimal level, it is advisable to use several different types of plants. If a monoculture were created, a nutrient deficiency can quickly arise, which can also lead to the formation of algae and damage to the health of the plants.

Carbon dioxide (CO2)
CO2 is an important element in the areas of plant supply and growth. The absorption of CO2 (photosynthesis) can lead to the development of oxygen, which is essential for all aquatic life. Too many plants in the tank use a correspondingly large amount of CO2 – a deficiency can occur that promotes the formation of algae. This can be remedied by a special CO2 system, which, however, must not produce too much CO2 because this would also have a negative impact on aquatic life and algae formation.

Fish food / feeding
When feeding, care should be taken that the dosage is well chosen. Too much feed often remains untouched and settles on the ground. There it can release nutrients and promote the formation of algae.

Water change
As far as the water change is concerned, it is only advisable to try it out. Some aquarium owners do well with a weekly water change of 25 percent or 50 percent. Others, however, have not been able to achieve any success against algae formation. Experts suspect the different results in the respective water quality, which can be different in every household. The motto here is: trying is better than studying.

Home remedies of a different kind

especially on the Internet, it is often recommended to put copper in aquariums to combat algae. Whether it works is not clearly proven, but that copper is toxic to fish has been scientifically proven. Therefore: no copper in the aquarium!

What has proven itself many times in ponds can also work in the aquarium: straw. That is how it goes:

  • Collect well dried wheat or barley straw
  • Use four to five handfuls of straw per 100 liters of water
  • Put the straw in a plastic bag and tie it
  • Poke numerous holes in the plastic bag
  • Place the bag in the basin and press down so that it fills with water
  • Expected effect: after around two days
  • Straw change: every ten days
  • Disadvantage: not a decorative sight

Home remedies and simple tricks offer possibilities to reliably prevent the causes of algae formation as well as this. There are no classic home remedies that can really be used successfully and prevent, apart from the straw bag. The only thing left for aquarium owners is to follow the instructions and tips here in order to get rid of algae and to be able to prevent them in the long term.

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