5 Surprising Facts About the Benefits of Algae in Aquariums

Alison Page

Alison Page


Surprising Benefits of Algae. Tropical fish with green algae in an aquarium.

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The mere mention of algae in their tank is enough to send most aquarium hobbyists into a full-scale meltdown. However, before you dismiss these green, slimy organisms as just a pain to be endured, you might want to take a closer look at their role in creating a thriving aquatic ecosystem.

In this article, I reveal five surprising facts about the benefits of algae in your aquarium. Prepare to be astounded!

Key Takeaways

  • Contrary to popular belief, algae contribute to the health of your aquarium by producing oxygen through photosynthesis and providing a critical food source for various tank inhabitants.
  • The presence of algae helps maintain the water quality by naturally utilizing nitrates, which are harmful to fish at high levels, reducing the need for excessive water changes and biological filter replacement.
  • Encouraging controlled algae growth can offer a more natural and stress-reducing habitat for your fish. Algae can also be aesthetically pleasing, representing the wild environment within the closed setting of your aquarium.

The Algae Advantage: Oxygen Production

Algae don’t just turn your tank water cloudy green; they are nature’s oxygen factories. Just like regular aquarium plants, algae use the process of photosynthesis to convert carbon dioxide into oxygen using energy derived from light, especially sunlight.

So, when the algae take up carbon dioxide and release oxygen into the water, they create a healthier, oxygen-rich environment for your fish and other livestock.

Algae as a Culinary Delight: A Buffet for Fish and Invertebrates

Algae serve as a natural and nutritious food source, offering a vibrant green buffet of microorganisms and small organisms that thrive within its structure. Some species of algae are a natural source of carotene, an essential vitamin that encourages the production of vitamin A.

Many fish and invertebrates use algae as a primary food source, which is why many experienced hobbyists, including myself, use a cleanup crew of certain snails, shrimp, and fish to keep their setups tidy by grazing on algae.

In fact, lots of fish, including the humble goldfish and many tetra varieties, eat algae throughout the day as a natural supplement to their captive diet.

The Aquarium Food Chain

In the intricate environment of an aquarium’s ecosystem, the humble algae is the foundation of the whole food chain. Tiny organisms feed on algae, larger ones feed on them, and the cycle continues.

So, by embracing so-called nuisance algae as a food source, you’re essentially sustaining a natural and harmonious ecosystem within your tank to the benefit of all your livestock.

Harnessing Algae for Water Quality Management

High concentrations of nitrates in the water are highly toxic for fish and invertebrates. Nitrates are a byproduct of decomposing fish waste, uneaten food, and decaying dead plant matter in the tank. Did you know that even the tap water you use to refresh and top your aquarium often contains a low level of nitrates?

In nature, the water is constantly refreshed by rainfall and natural evaporation, helping to keep the levels of nitrates and other toxins low enough not to harm your fish. But that can’t happen in the enclosed environment of a fish tank.

Of course, your biological filtration system should help to control the levels of nitrates in the water, provided you keep the filter media clean and change it regularly. Weekly partial water changes are also essential to remove nitrates from the water.

Green Nitrate Eating Machines

But did you know that all living aquatic plants absorb nitrates from the water column and the substrate, which is why I strongly recommend keeping a range of them in your tank. A flourishing display of vibrant green and red leaves gently waving in the current makes a strikingly beautiful display, too.

Although not quite as aesthetically pleasing, just like plants, algae are exceptional nitrate absorbers, acting as natural filters, taking up nitrates and utilizing them for growth. That not only helps in maintaining water quality but also reduces the frequency of water changes, helping to lighten your workload.

The Battle for Nutrients

That said, it’s essential to strike a good balance between the growth of beneficial algae and nuisance algae species. Nuisance algae species, such as green water algae and hair algae, are not generally appetizing to most tank residents and can outcompete other algae species and plants for light and nutrients.

So, striking a balance between potential troublemakers and beneficial algae is critical for a healthy aquarium.

Algae as Natural Habitat: Replicating the Wild Environment

Surprising Benefits of Algae. Tropical fish with green algae in an aquarium.

In the wild environment, you commonly see algae-covered rocks, submerged branches, and aquatic plants. By allowing the controlled growth of algae in your fish tank, you can replicate a more natural setting for your fishy friends and other aquatic pets.

When kept in an environment with a natural, homelike feel to it, fish are less stressed, making them less vulnerable to attack by parasites and diseases. Many species are more likely to exhibit their natural behaviors and often display much brighter, vivid coloration.

Algae and Biofilm – a Symbiotic Relationship

Biofilm is a thin layer of microorganisms that lives on the surfaces of your aquarium decorations and viewing panes, often coexisting with algae. The biofilm provides a food source for tiny organisms in the aquarium ecosystem and contributes to the overall health of the environment. Controlled beneficial algae growth can encourage the development of biofilm, which is hugely beneficial for the well-being of all your tank inhabitants.

The Aesthetics of Algae: Embracing the Green Canvas

Although I don’t deny that too much algae can sometimes cloud the water and obscure your view of your fish and carefully aquascaped aquarium, controlled algae growth can add a touch of natural beauty to your setup.

I like to intentionally cultivate certain algae species on some of the surfaces in my tank to create a more authentic, natural-looking underwater landscape. For example, I have several algae-covered rocks and pieces of driftwood that look stunning in the dappled light created by the plants growing above. I also like to allow algae to grow quite thickly on the back glass panel in the aquarium to hide all the external cabling and set off the bright colors of my fish.

Algae and Light: A Balancing Act

Getting the right lighting levels in your aquarium is critical for managing algae growth and keeping your tank looking good. To do that, you need to understand the lighting needs of all your aquatic plants and the algae you want without encouraging excessive proliferation.

One of the primary reasons for algae overgrowth in fish tanks is too much sunlight. So, if your fish tank is positioned in a spot where it catches some sunlight during the day, you’ll probably find that the algae growth is too aggressive and quickly overruns your aquarium. In addition, sunlight creates hotspots in the tank, which can lead to temperature shock for your fish.

Ideally, you want to have your aquarium in a position where the sun can’t reach it. That way, your fish will enjoy a stable water temperature throughout the day and night, and the algae will only receive sufficient light for moderate growth.

It’s all about achieving the right balance through trial and error until you get it right.

Final Thoughts

Algae play an essential, multifaceted role in the overall makeup of an aquarium’s ecosystem.

Through photosynthesis, these humble plants produce oxygen and remove carbon dioxide, which is great news for your livestock. In addition, algae take up nitrates from the water as nutrients, helping to keep the environment safe for your fish.

Many fish species enjoy nibbling on tasty green algae as a supplement to the diet you provide for them. Finally, algae can look truly beautiful when used to replicate a natural-looking, home-from-home environment for your fishy friends.

As responsible aquarium keepers, our challenge is not to wipe out algae entirely from our tanks but to use it as an attribute that benefits our fish and other aquatic creatures. So, the next time you spot a hint of green on your tank glass, don’t immediately try to eradicate it but see it as a living, breathing, essential component of your aquatic masterpiece.

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