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The Role Of Plankton In Aquariums

by Brian Dunleavy
The Role Of Plankton In Aquariums

When it comes to maintaining a thriving reef tank, one crucial element that often gets overlooked is the role of plankton. Plankton, particularly phytoplankton, plays a vital role in providing essential nutrients and food sources for various organisms in the reef ecosystem.

By understanding the significance of plankton and its impact on reef tanks, you can create a more balanced and vibrant environment for your fish and coral friends!

What Is Phytoplankton?

Plankton refers to all free-floating organisms in open water, both in marine and freshwater environments. While many people perceive plankton as a microscopic species, it is important to note that some plankton can be seen with the naked eye, such as copepods (see the image below) and certain jellyfish species. Plankton plays a crucial role in the marine food chain, serving as the primary food source for numerous organisms.


The Importance of Phytoplankton

Phytoplankton, also known as "plant plankton," are a type of planktonic organisms that are suspended in water. These microscopic plant organisms are responsible for manufacturing their energy through photosynthesis, using carbon dioxide and mineral salts present in seawater. 

Phytoplankton not only provide a significant source of oxygen for the Earth's atmosphere but also serve as the foundation of the marine food chain - including your reef tank!

Phytoplankton cultivation has become a key practice in the aquarium industry, to recreate a natural biotope within reef tanks. Unlike industrial products filled with chemical preservatives, live phytoplankton offers a more effective and organic solution for maintaining the health and balance of a reef aquarium. By embracing live phytoplankton, you can prevent the growth of harmful cyanobacteria, purify the water, and provide essential nutrients for corals and other organisms.

The Different Types Of Plankton

Plankton can be classified based on their life cycle and their position in the food web. Holoplankton are organisms that spend their entire lives as plankton, while meroplankton only spend a portion of their lives in this form. Phytoplankton, zooplankton, and bacterioplankton represent different trophic levels in the food web.

Phytoplankton: The Primary Producers

Phytoplankton, as mentioned earlier, are the primary producers in the planktonic community. These microscopic algae and cyanobacteria harness the power of photosynthesis to create their own nutrients. 

Phytoplankton come in various forms, ranging from single-celled species like diatoms and dinoflagellates to larger multicellular forms like seaweed. They contribute to the breakdown of organic matter, produce oxygen, and serve as a source of food for many aquatic organisms.

Zooplankton: The Consumers

Zooplankton, on the other hand, are the consumers in the planktonic community. These organisms rely on other organisms for their nutrition and play a crucial role in the marine food chain. Copepods and amphipods are common examples of zooplankton found in reef tanks. They feed on phytoplankton and other zooplankton, contributing to the overall balance of the ecosystem.

Bacterioplankton: The Decomposers

Bacterioplankton, as the name suggests, are prokaryotic organisms that play a vital role in the decomposition of organic matter. They consume the waste and byproducts of other organisms, contributing to the carbon cycle and nutrient recycling in the marine aquarium. 

Bacterioplankton have a significant impact on nutrient levels, including nitrites and nitrates, which are crucial parameters for maintaining water quality in reef tanks.

Live Vs Powdered Phytoplankton 

Live phytoplankton offers numerous benefits for reef tank enthusiasts. Unlike dry or powdered phytoplankton products, live phytoplankton provides a more natural and effective solution for nourishing the aquarium ecosystem. It is rich in essential nutrients, enzymes, and beneficial bacteria that support the overall health and well-being of the tank’s inhabitants. 

Live phytoplankton also helps maintain water clarity, aids in nutrient export and promotes the growth of beneficial microfauna in the aquarium.

The Role Of Plankton In Reef Tanks

There are 4 main benefits of phytoplankton in reef tanks:

  • Plankton has nutritional importance 
  • Plankton can help maintain biodiversity and balance
  • Plankton can help control algae growth 
  • Plankton can enhance zooplankton populations 

  • #1: Nutritional Importance of Plankton in Reef Tanks

    In a reef tank, plankton serves as a vital source of nutrition for a wide range of organisms, including corals, fish, and invertebrates. Phytoplankton, in particular, provides essential nutrients like amino acids, fatty acids, and vitamins that support the growth and development of these organisms. By incorporating live phytoplankton into your aquarium, you can ensure that their tank inhabitants receive a well-rounded and natural diet.

    #2: Maintaining Biodiversity and Balance

    One of the key benefits of incorporating plankton into a reef tank is the ability to maintain biodiversity and ecological balance. In the wild, coral reef habitats are teeming with diverse organisms, including sponges, bivalve mollusks, and various soft corals. However, replicating this level of diversity in a closed aquarium system can be challenging without the presence of plankton.

    Live phytoplankton feeds can help recreate a more natural ecosystem, providing a food source for these often overlooked organisms and supporting their survival inside your aquarium.

    #3: Controlling Algae Growth

    Plankton, specifically phytoplankton, can play a crucial role in controlling algae growth in reef tanks. By out-competing undesirable benthic algae, phytoplankton can help maintain a clean and balanced environment for corals and other sessile animals. 

    Additionally, the presence of zooplankton, which feeds on phytoplankton, can help control excessive algae growth by consuming the algae before it becomes problematic.

    #4: Enhancing Zooplankton Populations

    Zooplankton, such as copepods and amphipods, are essential for maintaining a healthy reef tank. These tiny organisms serve as a food source for many saltwater fish and invertebrates, including popular species like mandarin fish. 

    By incorporating live phytoplankton feeds into your aquarium, you can boost zooplankton populations, ensuring a continuous supply of live food for their tank inhabitants.



    Understanding the role of phytoplankton in reef tanks is key to maintaining a balanced environment for your fish and corals. From nutritional benefits to biodiversity maintenance, controlling algae growth, and enhancing zooplankton populations, embracing live phytoplankton cultivation contributes to the overall health of your aquarium.

    At Reefco Aquariums we offer both dry and live phytoplankton foods for your reef aquarium’s needs. Or if you want to try out growing your own live phytoplankton at home, take a read of our complete guide to growing phytoplankton!

    by Brian Dunleavy