How Many Moss Balls per Gallon? | What Are They? Complete Guide

How Many Moss Balls per Gallon

Marimo Moss Balls – What Are They?

Marimo is a Japanese term that means “seaweed ball”

The Marimo or Moss Ball (Aegagropila linnaei) is a variety of algae that, under specific circumstances, develops into green fluffy balls of moss.

Marimo moss balls were originally found in Japan in the 18th century at Lake Akan.

There are only a few places in nature where live Marimo are found, and those places are mostly in freshwater lakes in a few places: Japan (Lake Akan), Iceland (Lake Myvatn), Scotland, Estonia, and more recently, Australia.

Lake Akan is home to some of the world’s biggest marimo, with some measuring up to 30 cm in length (11.8 inches).

Although they seem to be composed of seaweed or moss, in reality, the bright green spheres are formed of a rare kind of algae. No solid substance can be found within the ball. The whole organism is composed of a mass of algae that expands slowly outward at a pace of about 5mm each year, eventually reaching a diameter of between eight and twelve inches.

Marimo moss balls are a popular option for fish tanks because of their low-maintenance care and fascinating forms. They, also, have the ability to be maintained in a bowl or vase in addition to the tank.

Marino moss balls are very resilient, making them an excellent choice for novices since they are very difficult to destroy. These incredible living spheres can live for more than a century!


Is It Actually Moss?

Unlike low-cost knockoffs (wrapped java in plastic or foam spheres), the moss ball is a genuine product. Marimo moss balls, by contrast, are little algal balls that appear very much like moss, hence earning the name “Marimo Moss Balls.” Their spherical form is due to the fact that they roll down the bottoms of rivers in the wild. The Japanese regard them as lucky charms and even handle them as if they were domesticated animals.


Marimo Moss Ball Basic Information

Scientific Name Aegagropila Linnaeii
Common Names Marimo Moss Ball , Marimo, , Moss Ball, Lake Ball, Seaweed Ball, Algae Ball, Mossimo Japanese Moss Ball
Origin The northern hemisphere lakes are home to the Marimo
Benefits Extremely low-maintenance and nearly indestructible
Life Span Marimo may live for more than a century if given the appropriate care
Care Squeeze the ball very periodically and rotate it to ensure that all sides of the ball are exposed to light in addition to your normal water maintenance.
Environment Keep at a lower temperature and away from direct sunlight
Growth rate The rate of growth is very low, approximately 5 mm per year
Reproduction Propagation is the most frequent method.
Other creatures The plant is snail-safe, and it is adored by the majority of other animals. It’s possible that goldfish will consume it


How Many Moss Balls per Gallon?

The number of moss balls you can pack into a gallon of water in your aquarium is really very considerable. You may use anywhere from one to three moss balls per gallon of water, depending on the size of the moss balls in question.

Generally speaking, 2.5-inch Marimo balls are suitable for all tank sizes, even large tanks.


5-gallon tank – 4-8 Marimo balls

10-gallon tank – 8-13 Marimo balls

20-gallon tank – 13-20 Marimo balls

30-gallon tank – 21-30 Marimo balls

55-gallon tank – 50-61 Marimo balls

100-gallon tank – 90-110 Marimo balls


With these figures, you can be certain that there are enough Marimo balls in your tank to maintain a healthy environment. However, adding too many of them might cause issues.

Moss balls may grow to be as large as 12 inches in diameter, but they develop over an eight-to-fifteen-year period.

You won’t have to worry about their size for a long time.


Marimo Moss Balls Benefits:

Clean Aquarium Water

Waste is produced by fish and other living organisms. Although the biological element of your tank filtration system deals with ammonia and nitrites, the nitrates that are produced as a byproduct of the process are still hazardous to your fish if levels increase above 20 parts per million (ppm). The addition of living plants and algae to the water supply can help to control the number of nitrates in the water as well as partial water changes.

Nitrates are extracted from the water and used as fertilizer by Marimo moss balls. Phosphates, debris, and ammonia are removed in small amounts by Marimo moss balls.

Moss Balls Increase the Amount of Oxygen in the Environment

Moss balls are involved in the process of photosynthesis, in which they absorb CO2 from the water and release oxygen. As a result, if you don’t want air rocks to disturb the surface of the water, a few moss balls can serve as a silent substitute.

Moss Balls are extremely low maintenance

Moss balls require little to no maintenance at all. Freshwater, dappled or dim lighting, and waste to feed on are all that are required for the balls to be satisfied. The moss balls will feed on the waste produced by your fish and other livestock, so you won’t have to worry about providing fertilizer.

As moss balls grow extremely slowly and evenly, there is no need to trim them. Instead, they simply increase in size very gradually over the years while maintaining their fluffy, velvety appearance.

Marimo Moss Maintain Control Over Algae Growth

It can be a nuisance when algae grow on the glass of your aquarium and spreads to cover your accessories and other aquatic plants. Marimo moss balls consume the same nutrients as other algae, causing them to starve as a result. Though the addition of a few moss balls to your aquarium will not eliminate other algae species, it will make it much more difficult for the undesirables to thrive.

Moss Ball

Moss Balls Are Simple to Clean

Frequent plants can accumulate a layer of algae on their surfaces, which can quickly become unsightly. Cleaning the leaves of the plants is time-consuming and frequently results in the plant being damaged.

On the other hand, Marimo moss balls absorb debris and dirt like sponges, which is excellent for your fish tank. Nevertheless, once the balls are completely filled, the detritus begins to leach out and pollute the water. For this reason, whenever you perform a water change, you should simply eliminate the moss balls from the aquarium and press them out over a sink.

Once the ball has been completely emptied of water and gunk, it can simply be placed back into your tank.

Marimo Moss Encourage the Growth of Beneficial Bacteria

A significant amount of surface area is provided by the biological filter media in your filtration system and the surface in your tank, both of which are important to the growth of colonies of beneficial bacteria. Those bacteria are critical in the processing of ammonia and nitrites in the water and in the maintenance of the nitrogen cycle.

Aquascaping Is Easy to Do

Moss balls are formed in nature as a result of the regular movement of the water current across the bottom of the lake. This is due to the fact that the algae spheres are literally rolled around on the substrate, which gives them their spherical shape. The movement also helps to expose all sides of the balls to a certain amount of light, which helps to prevent dead patches and keep the algae in good condition.

Due to the presence of beneficial bacteria on their surface, Marimo moss balls make excellent seeding material as well.

In your aquarium, the balls are more likely to remain stationary, and as a result, they will lose their shape over time.  Simply place one Marimo ball in the palm of your hand and lightly rub and roll it around to keep it in shape.

Adapts to High pH Environments

Many aquatic plants are unable to thrive in water with a high pH level. Moss balls, on the other hand, can withstand a pH range of 6.0 to 8.4 and still remain in good health.

Marimo Moss are Adored by Aquatic Creatures

Moss balls have a tendency to accumulate a layer of debris and nutrients over time, and several aquatic creatures take advantage of this by feeding on it. Fish,  Shrimp, African Dwarf frogs, and snails are all attracted to the moss balls and enjoy gnawing on the food particles that get nabbed on the moss balls.

Marimo Moss Balls and Betta Fish

Betta fish and moss balls can coexist peacefully in the same tank. Betta fish like playing with and relaxing on Marimo moss balls, which they find appealing for a variety of reasons, including their natural velvety-green brilliance and contrast with another décor. In one moment, you’re sitting on a velvet sofa, and in the next, you’re pushing about a soccer ball to keep it moving. It is particularly popular among ghost shrimp and aquarium snails, which are frequent betta tank companions, due to the moss ball’s capability of storing tiny bits of food for consumption by the fish.

Marimo moss balls can survive in the same water conditions as bettas do, although they develop more quickly in cooler water temps than in warm water. Until they are completely saturated with a tank, they will remain at the bottom of the tank and will only move when touched. Moss balls help to maintain beneficial aquarium bacteria, release oxygen, and decrease nitrate levels, all of which are detrimental to betta fish health when present in high concentrations.

Moss Balls Are Snail-Proof

Many species of ornamental snails are both beautiful and useful additions to your community, but the snails have a habit of snacking on live plants, which can be detrimental to the health of your plants. Snails, on the other hand, are uninterested in moss balls. Snails appear to be happy to feast on the food scraps that they find in the algae spheres rather than consume the algae spheres themselves.

Keep Water Pollution to a Minimum

Plants that are alive shed their old leaves and sprout new ones in their place. That’s just what healthy plants do when they’re happy. You will have to remove all of the dead leaves before they begin to break down and pollute the tank water, which will be a major inconvenience.

Marimo does not shed at all! They will remain fluffy, bright green, and intact as long as the moss balls are in good condition.

Tolerates the Presence of Aquarium Salt

It may be necessary to dose the aquarium with a small amount of salt from time to time to treat minor injuries and other. Salt is not a favorite of most aquatic plants. Moss balls, on the other hand, are tolerant of it. As a result, moss balls can be kept in a brackish tank, where other plants would die.

Are Marimo Moss Allowed to Roam Freely?

If you have fish species that are known diggers in your aquarium, regular plants can be uprooted in a matter of minutes, and you will spend the rest of your life replanting them in the substrate. In addition, some fish species, such as goldfish and silver dollars, are known for devouring tender shoots, leaving your prized plants looking ragged and tatty as a result of their predation.

In fact, there is no need to secure the moss ball in any way. When vacuuming the substrate and cleaning the tank, all you have to do is move the moss ball aside and clean beneath and around it, making your life a whole lot easier.

Moss Balls Are Inedible to fish

Although the fish and other inhabitants of your tank will enjoy gnawing on scraps of food from the exterior of the moss balls, nothing will be able to consume them in large quantities. Even the most voracious plant-eaters, such as goldfish, are unable to consume a moss ball.

If you have plant-eating species in your aquarium, this is fantastic news because you can now enjoy the many benefits that live plants provide without having to worry about your greenery being eaten for lunch!

Moss Balls Isn’t Going to Take Over Your Tank

Water plants spread and self-produce, gradually taking over the tank aquarium unless you regularly trim and thin them out to prevent this. The Marimo moss ball, on the other hand, is one of the most slowly growing aquatic plants you’ll ever come across. In spite of being kept in ideal growing conditions and receiving a constant supply of nutrients, moss balls will only grow 5mm per year on average.

You’ll never have to worry about the moss balls growing to the size of softballs in a matter of months and taking over your tank again.

Marimo Moss Are Very Simple to Grow and Propagate

It is not difficult to propagate the majority of popular fish tank plants, and the moss ball is no exception.

Moss balls may reproduce in two different ways: spontaneously and via artificial means. With a growth rate of just 5 mm per year, Marimo may take a long time to reach a size that is suitable for reproduction.

Natural reproduction consists of a tiny lump beginning to develop off of an existing Marimo, which will ultimately fall off and grow on its own after a period of time.

In the case of a bigger moss ball, however, you may want to propagate it by squeezing all of the water out of it, then splitting it in half, or even thirds or quarters, according to the size of the ball that you have. Continue to rotate the plant in the tank and gently roll it in your hands on a regular basis to encourage circular growth.


Marimo Moss Balls Disadvantages:

The Marimo, like any other product, has certain disadvantages

It has no effect on the health of large tanks

It provides many of the same advantages as plants. This includes the ability to absorb nitrogen and oxygen. It does so on a smaller scale when compared to the larger plants that are available. When we’re in the double-digit gallons range, it is frequently necessary to have more than a few plants. Huge amount of them could make a significant difference in nitrates, oxygen levels, and algae prevention. The addition of many different plant species to a tank may have a considerable effect on the tank’s overall level.

To accomplish this with the Marimo, you’d have to fill about a quarter of the tank with moss balls, which might look a little strange. It’s either that or make a moss ball the size of soccer ball out of it.

To have algae or nitrate management (although the moss ball may help), you’d have to purchase other plants in addition to the moss ball. The Marimo just assists in the resolution of these issues; it does not solve them by itself. So don’t expect a single moss ball in a 20-gallon tank to have a big effect on the environment in your tank.

It has a slow rate of growth

The Marimo moss ball has been the slowest-growing plant the aquarists ever encountered. The size of softballs or even larger has been mentioned. Although it is believed to take years (if not decades) for them to reach that size in an enriched environment. So, if you’re looking for a bigger ball, you’ll have to wait a while. If a moss ball becomes too large, it may be broken apart, resulting in the formation of smaller moss balls. You’ll need to reposition them on a frequent basis in order to make those irregular parts circulars again.

Of course, this implies that if the size of your moss ball is something you like, it will likely remain that size for a long time.

Goldfish will consume it

You shouldn’t be shocked if your goldfish rips this ball to pieces. They are notorious for eating everything that crosses their way.

It does not have the ability to reproduce

While aquatic plants multiply over time, moss balls will not reproduce in your aquarium. Instead, they will only grow in size. Consequently, you will not discover any baby moss balls or algae patches in this area. Depending on what you desire, this may be beneficial or detrimental. Only by ripping one apart will you be able to make additional moss balls, however it’s better just purchasing more. It may take years for a newborn moss ball to develop to the size of a golf ball.


Is it a right choice to have too many Marimo Moss Balls in One Aquarium?

It is not advised to use more than three moss balls per gallon of water. However, this is all subjective, and it is ultimately up to you to make the decision. It is determined by the number of other plants in the tank as well as the number of fish.

Keep in mind that everything in your aquarium need space to flourish. For example, if a fish requires 2 gallons of tank space and you have 6 moss balls, the total area available to the fish would be reduced.

As a result, we can conclude that determining how many moss balls are too many is a question of common sense more than anything else.


What is the maximum size of moss balls?

When allowed to develop in their natural environment, moss balls, such as Marimo moss balls, may reach a diameter of up to 12 inches when grown in the wild. As you can see, because of their enormous size, you can only have a limited number of them in a fish tank at any one time.

Even yet, in the context of the home aquarium, moss balls will seldom grow to be more than 5 inches in diameter. Also keep in mind that it will take a very long time for them to reach this size, since they grow at a rate of about 5 mm each year, which is half a centimetre, or approximately 1/5 of an inch, every year, on average.


Taking Care of Marimo Moss Balls:

Under normal circumstances and in good health, taking care of your moss ball is quite simple. They are very indestructible and will only need little maintenance on an as-needed basis. If they have access to clean water and are properly cared for, they may be able to live longer then a century.

Providing with Appropriate Lighting

The most essential thing you can do for your Marimo moss ball is to ensure that it receives the appropriate amount of natural light.

Because these plants grow near the bottom of the lakes, they get a moderate amount of indirect light.

However, avoid exposing the tank to direct sunlight for an extended period of time since it is detrimental to both your fish and the Marimo balls.

The temperature of the water will rapidly increase, the concentration of dissolved oxygen will fall, and your fish will be in danger.

If the Marimo balls are exposed to direct sunlight for an extended period of time, they will become white as well.

Creating a Suitable Setting

When it comes to tank housing, Marimos have minimal needs in terms of maintenance. However, there are a few things to keep in mind. First and foremost, avoid placing your moss balls in a location that receives a lot of sunlight. The fact that they normally occur on the bottoms of lakes where it is dark. It means that they do not respond well to direct sunshine.

An additional consideration is that, although certain aquarium residents, such as shrimp and dwarf crayfish, like foraging on and hiding behind Marimo moss balls. There’re other animals that enjoy it too much and will try to consume or destroy it if given the opportunity.

Plecos and goldfish often do not fare well in a tank with a Marimo since both fish like consuming green algae.  When you’re not sure if your fish or invertebrates will be interested in your Marimo moss ball, simply put it in a separate container to be on the safe side.

The Marimo moss ball is unique in that it can be maintained in a brackish water tank, which is very fascinating. It has been mentioned on many aquarium plant websites that it may survive in waters with salinities ranging from mild to moderately brackish. When handling with a Marimo moss ball that is turning from green to brown, it is sometimes necessary to add some salt to the water.


Do you want to know whether your moss balls need more fertilizers or food? No, they produce their own food via photosynthesis, which may be done with either natural or artificial light.

Marimo Moss Balls Cleaning

A marimo that is clean is a marimo that is healthy! Take the time to carefully wash your marimo moss ball once in a while. When you’ll notice the dirt particles have collected on it or if the green changed to brown or greyish, it’s time for bath. Squish it in a container filled with clean water a couple of times.

Afterwards, you may gently roll it around in your hands to avoid it from coming apart due to the squishing. However, this should be done with very caution. A re-rolled moss ball helps the marimo moss ball retain its round form. It would naturally acquire from being rolled over the lake bottom by the flow. Because this does not occur in a bowl, vase or aquarium on its own, it is recommended that you do it occasionally.

Marimo Moss Balls Water Change

It is important to change the water in your Marimo Moss Balls on a regular basis. This includes a bowl where you keep them by themselves or in a fish tank.

While some tank owners only do water changes every two weeks, others have discovered that their tank need weekly changes. Pay close attention to the bioload entering your tank. Also, check how your cleaning crew and filter are managing the trash.

Replace all of the water in the bowl, or about 25% of the water in a filtered tank. Water from the tap is generally sufficient for this purpose, but you may wish to dechlorinate it.

Low Temperature Water

Marimo moss balls are only found in colder climates such as Iceland and northern Japan. It likes colder water fish tanks. The container or tank becomes too hot (77° F/25° C degrees) during the summer. At this point, try temporarily relocating it to a little cooler location.

During the warm months, your Marimo moss ball may be stored in the refrigerator. Plus, a location near an air conditioner is also acceptable.

Marimo Moss Shape

Moss balls shouldn’t be left in a single position or on a single side for an extended period of time. Because of that they will begin to flatten.

Make care to roll them regularly to keep them fresh.

Types of Marimo Moss Balls:

Marimo Moss Balls are the most frequent kind.

Marimo Moss are a member of the Cladophoraceae algae family, which means they are green algae. They develop naturally when algae form a protective ring around itself. Moss balls are simple to spread and keep up to date.

Java Moss Balls are a kind of moss that grows in Java.

These are moss balls that have been produced and bonded to a Styrofoam core for stability. The majority of them are constructed with a ribbed plastic core to promote fast development. As a matter of fact, many amateurs create their own java moss balls. Maintaining their ideal form and size, on the other hand, may be a difficult job.

Moss Balls Made with Artificial Material

They are, as the name indicates, fake! They are little more than adornments for the room. What is it about them that makes aquarists like them? It’s possible that this is due to their low cost and little to no maintenance requirements. They are completely composed of plastic and provide secure hiding places for fries.

Ilnesses of Marimo Moss Balls

Marimo balls are resistant to a wide variety of temperatures and water conditions. As a result of a problem with their construction, they may develop a peculiar hue.

Marimo becoming white or lighter in color

Marimo becoming white or lighter in color indicates that it is getting an excessive amount of light. Another thing, if the Marimo ball seems to be a little sticky, or if its texture appears to be odd. It means, you may be dealing with harmful algae. The recommendation is to gently rinse them off or extract them with tweezers to avoid choking the slow-growing Marimo’s growth.

Marimo becomes brown

It’s possible that Marimo becomes brown since it’s time to carefully clean it. When all else fails, try gently plucking out the brown (dead) portions of the plant. Next, add a pinch of salt to the water to help the plant develop more quickly. It’s important to remember to rotate the Marimo ball around more often. The bottom of the ball goes brown as a result of not receiving enough light for extended periods of time. Rotating will help to avoid the Marimo from dying again.

Marimo is becoming black and/or falling apart

Marimo is becoming black and/or falling apart. With harmful algae or being too big to reach clean water, Marimo is notorious for rotting from the inside out. Trim the black portions of your Marimo moss ball. Next, carefully re-rolle the ball, in order for it to regain its health. It will be much smaller than it was previously, but it now has a decent chance of surviving and regenerating.

Maintaining a Tank Fully Loaded with Marimo Moss Balls

Fortunately, these creatures are very simple to care for. Having a large number of them will not add significantly to your regular tank maintenance time.

Whether you have one plant or a hundred, the only regular maintenance these plants need is:

Firstly, on a regular basis, you will need to roll them once each week to keep them in good condition. This will ensure that they remain spherical and don’t go flat on one side as a result of the process.

Ensure that you change out their water at least once every two weeks. This will ensure that the water with Moss balls is healthy and nutrient-rich.

You may also use this opportunity to rinse or swirl them in dechlorinated water. It will clean out any debris that may have accumulated on them.

Even if you have an aquarium full with Marimo balls, its’ maintaining should only take a few minutes.


To summarize, Moss balls may provide a variety of advantages for a fish aquarium. There is a strong suggestion to add some to your tank.

They assist to keep the water clean, fish enjoy them, and they are also very visually appealing. Plus, they need very little care, which is also very important. It’s a great choice for all aquarists’ levels, especially for beginners.

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