18 Benefits of Marimo Balls ( How many per Gallon? )

Living plants are extremely beneficial for fish tanks, soaking up harmful nitrates from the water to keep your fish safe, provide shelter for shy fish and fry, and create a verdant, beautiful aquascape for the onlooker to enjoy.

The main drawback of living plants is that they require a certain amount of maintenance to keep them healthy and looking good. Well, the best news is that you and your fish can still enjoy a natural green presence in your aquarium by choosing Marimo moss balls instead of regular aquatic plants.

What Are Marimo Moss Balls?

Marimo is a Japanese word that translates as “seaweed ball.”In nature, Marimo moss balls are found living in freshwater lakes in limited locations, including Japan, Iceland, Scotland, Estonia, and, more recently, Australia.

In fact, the vibrant green spheres are not made of seaweed or moss; but rather a rare form of algae. There’s nothing solid inside the ball. The whole organism is made up of a mass of algae, growing slowly outward at a rate of around 5mm every year, ultimately reaching between eight and 12 inches in diameter.

Marimo moss balls are incredibly hardy and almost impossible to kill, making them perfect for beginners. And these amazing living spheres can survive for over 100 years!

How Many Marimo Moss Balls To Use Per Gallon

As a general rule of thumb, it’s recommended that you keep between one and three Marimo moss balls per gallon of water.

18 Benefits Of Mighty Marimo Moss Balls

So, what’s so good about Marimo Moss Balls, and why do your fish need some in their aquarium?

1. Clean Tank Water

Fish and other living organisms produce waste. Although your aquarium filtration system’s biological element deals with ammonia and nitrites, the nitrates that are the end product of the process are still harmful to your fish if levels rise above 20ppm (parts per million). Partial water changes help control the level of nitrates in the water, but living plants and algae can also help.

Marimo moss balls absorb nitrates from the water to use as fertilizer and also remove small amounts of phosphates, debris, and ammonia.

2. Oxygenate The Habitat

As part of photosynthesis, moss balls take up CO2 from the water and release oxygen. So, if you don’t want air stones disrupting the water surface, a few moss balls can make a silent substitute.

3. Require Super-low Maintenance

Moss balls are almost maintenance-free. All the balls need to be happy is freshwater, dappled or dim lighting, and waste on which to feed. You don’t need to provide fertilizers, as the moss balls will feed on the waste that your fish and other livestock produce.

There’s no need to trim moss balls, as they grow extremely slowly and uniformly, simply increasing in size very gradually over the years while keeping their fluffy, velvety appearance.

4. Control Algae Growth

Algae in your tank can be a nuisance when it covers the glass and spreads over your decorations and other plants. Marimo moss balls utilize the same nutrients as other algae, effectively starving them. Although adding a few moss balls to your tank won’t kill other algae species, they will certainly make it much harder for the undesirables to thrive.

5. Easy To Clean

Regular plants can accumulate a coating of algae that quickly becomes unsightly. Cleaning the plants’ leaves is time-consuming and often results in damage to the plant.

In contrast, Marimo moss balls suck up debris and dirt like sponges, which is great for your fish tank. However, once the balls are full, the detritus begins to leach out into the water. So, whenever you carry out a water change, simply remove the moss balls from the tank and squeeze them out over a sink or bucket.

Once the ball is empty of water and accumulated gunk, you simply put it back into your aquarium.

6. Support Beneficial Bacteria

The biological filter media in your filtration system and the substrate in your tank provide a valuable surface area on which colonies of beneficial bacteria can grow. Those bacteria are vital to process the ammonia and nitrites in the water and keep the nitrogen cycle moving.

Marimo moss balls also make perfect seeding material by hosting beneficial bacteria on their surface.

7. Simple To Aquascape

In nature, moss balls are shaped by the water current’s constant movement across the bottom of the lake. The spheres of algae are literally rolled around on the substrate, which is why they are spherical. The movement also helps expose all sides of the balls to a degree of light, preventing dead patches and keeping the algae healthy.

In your tank, the balls are more likely to be stationary and will, therefore, lose their shape over time. To keep the Marimo balls in shape, simply take one in the palm of your hand and gently roll it.

Marimo Balls are widely used in Aquascape Aquariums

8. Adapts To High pH

Many aquarium plants don’t thrive in water that has a high pH. However, moss balls will tolerate a pH range of between 6.0 and 8.4 and remain healthy.

9. Aquatic Creatures Love Them!

Moss balls tend to accumulate a coating of debris and nutrients over time, and many aquarium creatures love to capitalize on that. Shrimp, African Dwarf frogs, fish, and snails all enjoy nibbling on particles of food snagged on the moss balls.

10. A Bettas Best Friend

Betta fish are curious, intelligent creatures, but because they tend to be aggressive, these beautiful fish are often kept alone. Marimo moss balls make the perfect betta fish companion!

The fish love to rest on the balls, using the soft, comfy algae spheres as a kind of cushion. Bettas also entertain themselves by rolling the balls around on the substrate and picking off scraps of food when they fancy a snap after playtime.

11. Are Snail-Proof

Although many species of ornamental snails can make a pretty and useful addition to your community, the mollusks do have a habit of munching on live plants. However, snails don’t bother with moss balls. Rather than eating the algae spheres, snails seem content to graze on the food scraps that they find there.

12. Don’t Pollute The Water

Live plants shed old leaves and grow new ones in replacement. That’s just what healthy plants do. Unfortunately, that means that you have to remove all those dead leaves before they start to decompose, polluting the tank water.

The Marimo doesn’t shed! As long as the moss balls are healthy, they remain fluffy, bright green, and intact.

13. Tolerates Aquarium Salt

Sometimes, you may need to dose the aquarium with a small quantity of salt to treat minor injuries and the like. Regular aquatic plants don’t like salt. However, moss balls will tolerate it. That also means you can keep moss balls in a brackish tank where other plants would fail.

14. Are Free-ranging

If you have fish species that are confirmed diggers, regular plants can quickly be uprooted, and you spend your life replanting them in the substrate. Also, some fish species, such as goldfish and silver dollars, are very quick to make a meal of tender shoots, leaving your precious plants looking ragged and tatty.

The moss ball doesn’t need to be anchored at all. That makes life super-easy for you when vacuuming the substrate and cleaning the tank; all you need to do is push the moss ball aside and clean beneath and around it.

15. Are Inedible To Fish

Although fish and other residents in your aquarium will enjoy nibbling scraps of food from the surface of the moss balls, nothing will make a meal of them. Even voracious plant-eaters, such as goldfish, won’t eat a moss ball!

That’s excellent news if you have plant-destroying species in your aquarium, as you can enjoy the many benefits that live plants bring without fear that your greenery will be eaten for lunch!

16. Are Virtually Indestructible

Unless you dunk it in chlorine-filled water, put it in water that’s devoid of nutrients, or try to put it in a marine tank where the salinity levels are high, you won’t kill a Marimo moss ball.

As long as your tank is well-maintained and the lighting is not too bright, the Marimos should do fine. Keep an eye out for white flecks on the moss balls, which indicates too much exposure to light or brown patches that means they’re getting insufficient light.

17. Won’t Take Over Your Tank

Most aquatic plants spread or self-propagate, gradually taking over the tank unless you regularly trim them or thin them out. However, the Marimo moss ball is just about the most slow-growing aquatic plant you can find. Even when kept in the perfect growing conditions and provided with a ready supply of nutrients, moss balls grow just 5mm every year.

That means you’ll never have a problem with the moss balls growing to the size of softballs within a few months and taking over your tank!

18. Are Super-Easy To Propagate

Most popular aquarium plants are easy to propagate, and the moss ball is no exception to that rule.

To create more moss balls, simply tear a piece off an existing specimen, roll it into a ball, and pop the new plant into your tank. The only downside to that method of propagation is the slow growth rate of the plants. I actually prefer to buy more moss balls, unless I want a few tiny ones for my aquascaping design.

Where to buy Marimo Balls?

Final Thoughts

Marimo moss balls are a fantastic plant substitute that are super-easy to care for and are tolerant of a wide range of water parameters.

So, if you want to add a splash of color to your aquarium and you’re looking for something a little quirky, a few of these fascinating little organisms will only benefit your setup.