Are Moss Balls Good for Fish Tanks? 14 Benefits

Two Moss Balls in Freshwater Fish Tank With Pleco and Gold Fish -

They’re known by many different names, but the most common one is Marimo, a term that comes from the combination of two Japanese words – ‘mari’ (bouncy ball) and ‘mo’ (aquatic plant).

No matter what you call them, they’re a popular addition to aquariums of any size because they are hardy and low maintenance option for adding some living greenery to the environment.

Are moss balls good for fish tanks? There are numerous benefits to adding one or more marimo balls to your tank. These range from benefits to the aquarium’s residents and the water quality in your tank to benefits to your convenience and enjoyment as an aquarium keeper. As a rule, moss balls are a great addition to any tank. There are few exceptions due to demanding care or downsides.

If you’ve seen them in a pet store or local aquarium supply store, you might think they look like something a cat would cough up.

If you’ve seen them in their fully developed glory in a friend’s tank, you might have thought it was artificial.

Marimo balls have a story worth knowing and a lot to offer when you introduce them to your tank. Read on to learn everything you need to know about moss balls.

What are Moss Balls Used for in Aquariums?

Betta Fish in Freshwater Fish Tank Setup With Tree Moss Balls -
Picture: Betta Fish and Moss Balls in Fish Tank

The first thing that you need to know about moss balls is that they aren’t really a moss at all. They are a species of wild algae that is native to Japan and some parts of Europe.

Aegagropila linnaei is a filamentous green algae that grows in rivers, lakes. It is not uncommon to find it growing in mats on a lake and river beds throughout its geographic range. Naturally, occurring marimo are rare and protected.

Moss balls, also known as Cladophora balls, form when the filaments of the algae are rolled by the action of currents.

The right balance of currents, light, water quality and substrate conditions required to promote colonies of natural moss balls is rare.

Japan, Iceland, and other countries where natural colonies exist have taken steps to protect them. The moss balls for sale in pet stores come from Ukraine.

Marimo are hardy and slow-growing. They thrive in a wide range of water temperatures, light levels, and pH levels.

They are popular with most fish and invertebrate species, and they do as well in a tank by themselves as they do in a stocked freshwater aquarium.

For all of those reasons, they are a great option for inexperienced aquaculturists and folks who’ve struggled with living plants in the past.

Of course, the ease of keeping marimo is just one of the reasons that you should consider adding them to your tank.

Even experienced aquarium keepers with a certified green thumb will love the work that they do to improve water quality and add to the enjoyment that both they and their pets get from the tank’s environment.

Let’s take a look at some of the main benefits of adding moss balls to your tank.

14 Benefits of Marimo in Your Fish Tank

Pleco Tasitng Moss Ball In Freshwater Fish Tank
Picture: Pleco Tasting Moss Ball In Freshwater Fish Tank

Every part of your fish tank set up can be evaluated with a cost-benefit analysis. Not having a fish tank at all would require zero effort and so it would cost you nothing.

But it would also mean that you wouldn’t get the benefits of having something interesting, beautiful, relaxing, and fun in your space. Filters deliver considerable benefits by maintaining water quality, but they require investments in the form of power to run them and work to maintain them.

One of the best things about moss balls is that they are light on costs and heavy on benefits.

#1 – Moss Ball – Absorb Nitrates

Fish waste in your tank leads to the accumulation of nitrates, nitrites, ammonia, and phosphates. Moss balls, like all living plants in your aquarium, help to maintain healthy water quality by absorbing those potentially harmful compounds.

While a single moss ball won’t be enough to replace a filter in a tank that is larger than a few gallons, it will make a beneficial contribution to the overall effort.

#2 – Moss Ball – Oxygenate Water in Tank

Like all plants, moss balls use photosynthesis to survive. That means that they absorb CO2 and release oxygen.

You might even see your marimo floating in the tank as built-up levels of oxygen dissipate into the water. Maintaining healthy oxygen levels in your aquariums water is important to the health of your fish and other creatures. Every little bit helps, and moss balls add to the total.

#3 – Moss Ball – Prevents Excess Algae Growth

Using algae to prevent algae is the definition of fighting fire with fire, right?

Because marimo consumes the nutrients that other, less desirable forms of algae would need in order to thrive in your tank—having marimo goes a long way toward eliminating unwanted algae.

Just as the size of your tank will determine the impact that each moss ball has on the level of nitrates and amount of oxygen, so to will it determine the impact on controlling unwanted algae.

#4 – Moss Ball – Harbor Beneficial Bacteria

Maintaining a healthy tank is all about creating the right balance between bio-load and filtering.

We use filters and water changes to combat the build-up of nitrogen from fish waste and other sources.

One of the most important weapons in the fight against tank water toxicity are the colonies of healthy bacteria that grow in our tanks.

Moss balls provide a surface to grow on and beneficial seeding material.

#5 – Moss Ball – Low Maintenance

If you have a tank with fish in it, you have everything that you need to keep a moss ball happy and healthy. They feed off the waste from the fish in your tank, and they don’t need much light to do well.

They prefer shade, but they tolerate a wide range of light, temperature, and pH levels. They don’t need to be anchored to the substrate, so you just have to toss them in, and they’re good to go.

Since Cladophora absorbs so much from your tank’s water, they tend to bite off more than they can chew. That means that nasty stuff will leach out unless you ‘re-set’ them periodically.

All it takes to do so is give the moss ball a squeeze over a sink or bucket during each routine partial water change.

Squeezing the water out of the moss ball means that it will float when you put it back in the tank. This isn’t harmful and only lasts until the moss ball absorbs enough water to make it sink.

You can accelerate the process by giving the moss ball another squeeze once it is back in the water in the tank.

The only other thing that it takes to maintain a marimo is keeping an eye on it to make sure it gets enough light on all of its surfaces. If you are moving the ball to perform cleaning, then you’ll be moving it as much as it needs.

But if you start to notice browning or yellowing in the areas that the ball is resting on, just give it a roll to expose them to the light.

#6 – Moss Ball – Adapts to High pH

There aren’t many aquarium plants that can handle water that is high in pH, but a moss ball will be perfectly happy in water that is in the mid- to high-8 range on the pH scale.

#7 – Moss Ball Makes Happy Critters

Crayfish on Moss Ball in Freshwater Fish Tank
Picture: Crayfish on Moss Ball in Freshwater Fish Tank

Adding a moss ball to your aquarium adds another element to the diversity of the environment.

There are certain species, such as shrimp and frogs, who love foraging for food in moss balls or using them as a hangout. Bettas and goldfish have been known to roll the balls around the bottom of tanks or ‘play’ with them when they float.

A marimo can be many things to many critters all at once.

#8 – Snail-Proof

If snails are part of your strategy for combatting algae in your tank or you’ve had some slip in unintentionally when you introduce something new to your tank—you know how tough they can be on living plants and what a mess that can make from dead organic matter.

But moss balls are virtually snail-proof. Some snails will nibble at the moss ball the way shrimp do, but you won’t have to worry about them killing it.

#9 – No Dead Matter with Moss Balls?

Most plants grow new leaves and shed old ones as part of their life cycle. Marimo does not.

They grow slowly, and they don’t reproduce on their own. You can trim them or split them if you wish, but that isn’t necessary.

What this means is that you’ll never have to worry about unsightly debris or elevated water toxicity due to your moss ball doing its thing.

#10 – Moss Balls are Salt Tolerant

If you’ve ever had to use freshwater aquarium salt to treat injuries, illnesses, or an outbreak of parasites in your aquarium—you know how harmful it can be to aquatic plant life.

Salt can also be an important tool in reducing nitrate levels in your tank. If you have moss balls in your aquarium, you won’t have to worry about what the salt will do to them.

#11 – No Stowaways

If you’ve had negative experiences with other living plants in your aquarium, one of the possible reasons for that was the accidental introduction of snails or parasites that rode in on the backs of the plants.

Moss balls are sold in individual cups, so there is a much lower chance of a hitchhiker tagging along for the ride. Check these options on Amazon – 6 pcs of Moss Ball selection  or check your near by Pet Store.

#12 – No Anchoring Required

Unlike other aquatic plants, you won’t need to have a particular type of substrate in your tank or do any work to anchor them. While that isn’t necessary to have a happy and healthy marimo in your aquarium, they are versatile enough to allow you that option if you choose to do so.

Since the algae grow as a mat as well as it does in the form of a ball, you can split the ball, lay it flat, and anchor it to decorate your tank.

#13 – A Very Hardy Addition

It is “almost” impossible to kill a marimo without intentionally trying to do so. Untreated tap water, saltwater, and water without nutrients will all do a moss ball in, but short of that, they are going to survive.

  • If you notice white specks on your marimo, it is suffering from over-exposure to light—easy enough to fix.
  • If you notice brown patches or your moss ball floats and doesn’t resettle then it is suffering from a lack of light. Keep an eye out for these issues and chances are your marimo will outlive you.

#14 – Aesthetics of Moss Ball

We’ve talked a good deal about how much good a moss ball can do for your fish tank. What we haven’t mentioned yet is the one thing that should go without saying but cannot.

They just look cool. Adding one or more to your tank will add vibrant life to your aquarium, and you and your fish will enjoy it more.

How Long Doe Moss Balls Last?

Hidden Betta Fish near Moss Balls In Freshwater Fish Tank
Picture: Hidden Betta Fish near Moss Balls In Freshwater Fish Tank

Marimo are slow-growing and long-lasting. They don’t reproduce, but they can be split if you want to turn one large one into two smalls ones. There are very few things that you can do to kill them unintentionally.

So, under almost any circumstance, you can expect them to live a long and happy life. They have been known to live for more than 100 years.

Are There Any Downsides to Moss Balls?

Amano Shrimp On Mass Ball In Freshwater Fish Tank
Picture: Amano Shrimp On Mass Ball In Freshwater Fish Tank

There really aren’t any negatives that you need to worry about if you’re thinking about getting a moss ball – or more than one – for your aquarium. There are, however, a few limitations that you need to be aware of while you’re thinking it over.

One of the biggest downsides to marimo is that they have a limited effect on your tank’s water quality. There is only so much than each individual moss ball can do, and your tank would look a little weird if it were half-full of moss balls. So, they aren’t an alternative to a filter system in a large tank, just a useful addition.

Another downside of moss balls is that, unlike most other aquarium plants, they don’t reproduce. They are slow to grow too. So, if you want more moss balls, you’ll have to buy more.

A final downside worth mentioning is that some species, like goldfish, axolotls, and turtles, will either feed on or intentionally destroy your marimo. They are way too expensive to use as goldfish food, so you might need to reconsider your plans if the species you keep enjoy your moss balls too much.

What Are the Care Tips for Moss Balls?

2 Moss Balls On The Tray Freshwater Fish Tank
Picture: 2 Moss Balls On The Tray – Freshwater Fish Tank

Moss balls are an extremely low maintenance aquarium plant. Even so, there are some things that you need to know to keep them happy and healthy:

  • They prefer cooler water – 85°F probably won’t kill a marimo, but they’ll be a lot happier at 60°F.
  • Keep them out of direct sunlight
  • If a marimo gets too large – Divide and re-roll
  • If a marimo starts to come apart – open it, remove any dead matter and re-roll
  • Reposition your marimo occasionally to make sure the whole thing receives light
  • Squeeze the marimo to wring out contaminants during routine partial water changes

If you follow these simple guidelines, your moss ball is going to be just fine in almost any freshwater fish tank. They can even do well in brackish water.

Just like any other living thing, you’ll have to keep an eye on your moss ball for signs that it isn’t doing well. But if you use common sense and do what you need to do to keep your aquarium suitable for fish and other critters, you’re going to see happy and healthy marimo.

If you’re still reading at this point, you have probably gotten the impression that we are pretty big fans of what moss balls bring to a fish tank.

I think that if you give them a try in your own aquarium, you will quickly come to agree with me.

Take advantage of the benefits they provide and the versatility that they offer. Get one for your tank and see how your fish and animals feel about the new décor.

Moss Ball Conclusion

Mass Ball On Gravel In Freshwater Fish Tank and Two Angel Fish -
Picture: Mass Ball On Gravel In Freshwater Fish Tank and Two Angel Fish

Marimo are a naturally occurring phenomenon that has been domesticated so that they can be available to those of us who keep aquariums.

Having one as part of your tank’s environment gives you something interesting to talk about with visitors and guests. It also brings vibrant green life to the environment—which is something that both you and your fish will enjoy.

On top of that, moss balls do their fair share of the work that it takes to keep your tank’s water quality high.

For all of these reasons, we would recommend giving marimo a shot at being a part of your aquarium. But at the end of the day, all of the good things that moss balls do are just features.

The real benefit is the cool factor that they introduce with their unique looks.

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