Aquarium Probiotics for Beginners

By Alberto Roy

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Aquarium probiotics support the well-being of water tank inhabitants. However, in the context of aquaristics, probiotics are not precisely the same as the probiotic bacteria and yeasts that humans consume as dietary supplements. Typically, the term “aquarium probiotics” refers to beneficial bacteria that establish and sustain a healthy environment for aquatic life.

Read the following article to learn more about these organisms and their contribution to the well-being of aquarium dwellers.

What are beneficial aquarium bacteria?

In the context of aquaristics, the term “probiotics” most often refers to the bacteria involved in the nitrogen cycle, a natural process for waste disposal in an aquarium. Food residues and, especially, fish excrement contain ammonia, which is toxic to aquatic inhabitants.

Probiotics play a crucial role in converting ammonia into less harmful substances like nitrite and nitrate. Moreover, aquariums lacking probiotics create auspicious conditions for the growth of harmful bacteria, which can lead to a decline in water quality.

Some of the key bacteria participating in the nitrogen cycle include ammonia-oxidising Nitrosomonas, responsible for converting ammonia into nitrite. Subsequently, Nitrobacter and Nitrospira transform nitrite into the even less harmful nitrate.

Where can you get probiotics for your aquarium?

There are two primary sources of probiotics available to aquarists.

If you have access to an established, healthy aquarium, you can use its water or filter media, which already contain populations of beneficial bacteria, to introduce into your new or existing aquarium.

Alternatively, you can purchase dedicated bacterial supplements. For example, some aquarium additives like those offered by Aquaforest are formulated to support beneficial bacterial growth. When using these supplements, it is crucial to carefully follow the instructions provided by the manufacturer.

How to promote the growth of beneficial bacteria?

While maintaining your aquarium, it is important to consider the well-being not only of your fish and corals but also of the probiotics that play a vital role in the ecosystem.

  • When setting up a new aquarium, initiate the nitrogen cycle without introducing fish. Provide a source of ammonia, which can be fish food or pure ammonium chloride.
  • Ensure that your filter equipment is well-maintained to provide proper filtration in the aquarium. Avoid cleaning or replacing all filter components at once to preserve the bacterial colonies that thrive on the filter’s surfaces.
  • Refrain from excessive cleaning of the aquarium. Just as with the filter, it is advisable not to clean every surface of the tank at once or replace the entire substrate.
  • Overfeeding can lead to ammonia spikes as excess food decomposes.
  • Exercise caution when using medications in your aquarium, as some can harm the beneficial bacteria. Follow instructions closely and monitor water parameters during treatment.


Although unseen to the naked eye, probiotic bacteria play a significant role in aquariums, where they clean water from toxic substances and prevent the proliferation of harmful bacteria, which can cause a further decline in the quality of water. Just like aquarists take care of fish, they should be attentive to the needs of beneficial bacteria to allow their tank to thrive. Find more at:

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