Spirulina fish food benefits
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Spirulina Fish Food: A Nutritional Powerhouse

Spirulina the unappealing green powder you often come across in health food stores, is one of the most consumed supplements in the world.

For humans, its high antioxidant content and broad vitamin profile has been proven to lower cholesterol, improve digestion, lower cancer risk and many other health benefits.

But did you know it’s also incredibly healthy for your fish?

Spirulina has been used by fishkeepers for decades as a way to complement the daily diet of their fish, offering health benefits that regular commercial food can’t offer.

This article will cover exactly what this nutritional powerhouse is, where it comes from, how it can benefit your fish’s health as well how to use it for optimal benefits.

Feeding your fish spirulina
Spirulina, as seen under a microscope

Spirulina is a type of blue-green algae (or Cyanobacteria) that is found in salty lakes and oceans in subtropical climates.

Cyanobacteria’s are technically algae, but they differ from most algae’s due to their ability to produce energy from the sun, just like plants.

It’s also one of the oldest cultivated foods in the world, with reports of the Aztecs using the algae as food, thousands of years ago.

Fun Fact: It’s also been proposed by astronauts at NASA as a potential food source that can be grown in space.

The majority of natural spirulina powder and supplements are produced in South America and Western Africa.

The term “Spirulina” is essentially a marketing term to make the idea of eating algae more tolerable.

It’s certainly more marketable than “pond scum” which is essentially what algae is.

We aren’t talking about human consumption though. I’m sure our fish won’t mind where the food comes from or what it’s made out of as long as it ticks a few boxes:

  1. It tastes nice
  2. It provides them with energy and nutrition
  3. It’s consistent (fish love consistency)

But that’s not to downplay the benefits of spirulina as a fish food supplement.

It’s cram-packed with several nutrients that are crucial for boosting and maintaining good health in your fish.

A single block, pellet spoonful of spirulina includes:

  • Calcium
  • Potassium
  • Magnesium
  • B-Vitamins
  • Niacin
  • Iron
  • Up to 70% protein

You’re probably thinking…

Well that sounds great, but what does that mean for my fish?

The Health Benefits of Spirulina as Fish Food

Boosted Immunity

The dense nutritional-profile of spirulina provides an all-round health kick for your fish’s immune system.

A stronger immune system makes them less susceptible to catching bacterial and fungal aquarium diseases.

Improved Colors

The biggest benefit of a healthier immune system, outside of a stronger defence against disease, is that it will encourage more vivid coloring.

As with humans, a healthier diet filled with nutrients, antioxidants and anti-inflammatory properties will lead to healthier skin, nails hair and an overall glow that can only be achieved through good nutrition.

It’s Anti-Bacterial

There are several common diseases among fish that are caused by bacteria.

Two big examples are fin rot and swim bladder disease (note: this can also be caused by digestive issues)

I can’t promise that adding spirulina to your fish’s diet will make them immune from bacterial diseases, but it’s nutritious and could potentially help to reduce the risk… so why not?

Its high antioxidant count and anti-bacterial properties can protect your fish from the inside, making them less likely to be severely damaged by a disease if there is ever an outbreak in your aquarium.

It’s Good For Digestion

Spirulina is a fibrous plant matter, providing a boost in your fish’s digestive health.

I’m not an expert on ‘Aquatic gastroenterology’ (is that even a thing?), so I can’t tell you the ins-and-outs of why, but from my experience as a fishkeeper, there’s not much better for helping constipated fish.

I’m sure it’s just as helpful for other digestive issues as well, so it’s always worth having some in your cupboard, ready to offer your fish on a consistent basis – to keep the pipes clean, so to speak!

Where Can I Buy It? Which One Should I Choose?

Spirulina found in most stores will be typically sold as either a powder, a pressed pellet, or a flake.

For your aquarium however, there are a few different ways to introduce spirulina depending on the specific requirements of your fish.

For general everyday use…

Spirulina-based foods will be sufficient. In most commercial spirulina-based foods, spirulina will only make up a small amount (maybe 5 – 10% by weight), which doesn’t seem like much, but as it’s a daily food, you’re simply adding a small amount to your fish’s diet, every time they eat.

Using a daily spirulina-based food will ensure your fish are getting just the right amount without the worry of overfeeding.

If you want to offer your fish a boost of health without changing their daily food, you can throw in a few spirulina flakes every few days.

Spirulina flakes for fish

The healthiest ones I’ve found are the ones from Ocean Nutrition (available on Chewy).

They are packed with other nutritious treats such as brine shrimp and krill. It’s all real food. No chemically altered nonsense.

I see them as little nutrition bombs that I drop into my tank every third day. My fish absolutely love them and the benefits are apparent after a few weeks.

A quick note for those with bottom-feeding fish:

Certain species of fish such as Plecos (who love spirulina) will likely never see an ounce of the flakes you are adding to your tank, as they are bottom-feeding fish.

If you’ve got bottom-feeding fish who you would like to feed spirulina, make sure you choose a sinking pellet and not a flake.

For pond fish: a floating pellet with added spirulina will be the best option.

How To Use Spirulina as Fish Food

So now that we’ve covered what spirulina is and how it can benefit your fish, let’s look at how you should actually use it.

Again, the process will depend on your specific situation, but as a rule of thumb, the best way is to feed your fish a daily food with added spirulina.

There are only a few situations (such as feeding your own cultured live-foods or fry) where powdered spirulina would be necessary.

The best daily food with spirulina is definitely Spirulina 20 from Zoo Med.

It contains tons of protein and is packed full of nutrients that your fish need to thrive. It’s an ideal daily food because it covers all of the bases nutritionally as well as injecting a powerful dose of the mighty spirulina.

Oh, it’s pretty cheap too (it’s even cheaper if you select auto-ship on Chewy – get it delivered monthly so you never run out)

How Much Spirulina Should I Use?

Spirulina is not a complete food that can sustain your fish on its own.

It’s simply a supplement and should be administered as one.

A well-rounded daily food with added spirulina will typically have between 5 and 10 percent of its weight as spirulina (or 20% if you choose Spirulina 20).

Feeding your fish their normal dosage (it varies greatly, as you know) will provide them with enough Spirulina without going overboard.

If you’re going with he spirulina flakes (which have a higher spirulina content), you can offer them as you would any other treat. A pinch here and a pinch there.

Be sure to check the packaging of any products you put in your aquarium to double check the recommended dosages.

So, let’s wrap this up…

Hopefully this short article has given you some more insight into the superfood spirulina and what it can do for your fish’s health.

I can personally vouch that it will boost their overall vitality (they may seem more active or playful), it will clear up any digestive issues as well as protect them against disease.

So now I turn the questions over to you…

Have you ever used spirulina as a fish food? What benefits (if any) did you see?

Will you be trying spirulina as a fish food after reading this article? If not, why?

I love to hear your opinions. This is a community website and we love to hear your thoughts. Please comment below of check out our Facebook page!

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  1. Heidi Cole says:

    Hi I’ve just inherited a 65 litre fish tank that has 3 penguin tetras 2 mollies 1 rainbow shark and a pleco.

    I’m an absolute newbie. But over the last month I’ve removed all the plastic plants and replaced them with living ones in ceramic rocks and the gravel for sand and JBL Manado substrate.

    The food I was given is Aquarium flakes, but after doing some research I have purchased some spirulina granules and some freeze dried Artemis cubes.

    Hopefully I’m doing the right thing and the fish will be both happy and healthy.

    But would really appreciate any advice offered to maintain the balance of their natural environment.

    Thank you. Regards Heidi

    1. Hi Heidi! We have the perfect piece to answer your questions about a balanced aquarium. Check this out!

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