Marimo Moss Balls in aquarium

Marimo Moss Ball – Aquarium Guide

Marimo Moss Balls are actually a type of algae, scientifically known as Aegagropila linnaei, and grow naturally in cool, freshwater lakes in Japan, Iceland, Scotland, and Estonia.

While you might be wondering if Marimo Moss Balls are a live? It’s a yes, but alive in the same way all plants are. They grow, they react to their environment but they aren’t animals.

It’s difficult to pinpoint the exact time they first arrived in aquariums, but there’s no doubt there popularity has grown massively in the last 20 years.

Related: View all our Freshwater Plant Guides

Japanese botanist Tatsuhiko Kawakami first studied and named Marimo Moss Balls as “Lake Ball” in 1898, and their natural habitats have been protected by law in Japan since the 1920s.

As the aquarium hobby grew, enthusiasts started to recognize the unique aesthetic and functional benefits that Marimo Moss Balls offered, leading to their current widespread use in aquariums around the world.

Now that we know a little more about these cute little plants. Let’s take a look at some reason why you might want them in your aquarium, and why you might want to skip them.

Detailed view of Marimo Moss Ball

Marimo Moss Balls – Facts & Overview

Nothing adds cuteness to a nano aquarium more than a few Marimo Moss Balls covered in shrimps.

These little spherical balls can grow up to 5 inches in diameter in an aquarium setting, but their growth rate is very slow, often taking years to reach full size. In the wild, there have been recorded cases of Marimo Balls living for closer to 200 years. So your Marimo might just outlast you and your pet turtle!

We also get asked a lot: How long can Aquarium Marimo Moss Balls live for? Around 50 years of lifespan if kept in healthy water parameters with adequate lighting. More on that later.

How old is a 2 inch Marimo Moss Ball? around 10-14 years old already.


  1. Natural Filtration + Oxygen Production: Like all plants, they absorb nitrates, phosphates, and ammonia from the water while adding oxygen for your fish.
  2. Aesthetics: Their unique, lush green appearance adds a beautiful and natural touch to any aquarium.
  3. Low Maintenance / Beginner Friendly: They are easy to care for and don’t require any special lighting, substrate, or fertilizers.


  1. Slow Growth: Since they only grow around 1-4mm a year, you’re best buying a larger size to begin with. A 4 inch ball can already be 20 years old.
  2. Not Suitable for Warm Water: They prefer cooler temperatures, so they may not thrive in tropical aquariums with temperatures above 77°F (25°C).
  3. Often Contaminated: It’s common for them to arrive covered in pesticides and will need to be quarantined (Especially if ordering online and from overseas. (See our Marimo Moss Ball quarantine guide below).
Marimo Moss Balls 0.8cm to 3cm

Different Types of Marimo Moss Balls

There is only one species of Marimo Moss Ball, Aegagropila linnaei. We’re yet to see any unique variations or colours appear for this these cute little balls.

If you’re looking for some unique plants for your aquarium, check out our Anubais Guide where we cover some rare & unique colour variations.

Kh and Temps for Marimo Moss Balls

How to Care for Marimo Moss Balls?

Tank Size & Water Parameter Requirements

Moss Balls are adaptable and can thrive in any size aquariums or containers. However, it is essential to provide enough nutrients & light for them to grow.

They will also adapt to a range of water conditions, but let’s help them thrive:

  • Temperature: Marimo Moss Balls prefer cooler water temperatures (68-77°F)(20-25°C).
  • Avoid placing them in warmer tropical aquariums.
  • PH: between 6.0 and 8.0 is ideal for Marimo Moss Balls, as it closely mimics their natural habitat conditions.
  • Lighting: They can also tolerate low to moderate light levels. High lighting will cause algae and stunt their growth.
  • Water Hardness: They tend to grow more in soft to moderately hard water. (GH) of 5-15 dGH and (KH) of 3-8 dKH.
  • What do these Moss Balls eat? like most aquatic plants, they draw their nutrients from the water. The main ingredients a Moss Ball likes to eat are Nitrogen (N), Phosphorous (P), and Potassium (K). But they’ll also draw out small amounts of calcium, magnesium, iron, zinc, copper & manganese from the water. The rest of their Energy comes from Carbon Dioxide and Light Photosynthesis.
Marimo Moss Balls

How to add Marimo Moss Balls to your Aquarium?

  1. Quarantine: First quarantine them for 1-2 weeks (See below).
  2. Rinse: Rinse them gently under cool, dechlorinated tap water to remove any debris or contaminants.
  3. Add: Place them in your aquarium, ensuring they are not obstructed by decorations or other plants.


It’s essential to quarantine new Marimo Moss Balls for 1 to 2 weeks before introducing them to your aquarium.

  • Place them in a separate container with dechlorinated water.
  • Monitor for signs of disease & pests.
  • Depending on your preference (I enjoy mystery snails), you might want to also check for eggs from mystery snail hitch-hikers.
  • Change water & gentle massage regularly to remove pesticide residue.
Quarantining Marimo Moss Balls

Maintenance and Care

Marimo Moss Balls are incredibly easy to care for, making them a popular addition to aquariums.

  1. Rotate them regularly to ensure even exposure to light, promoting uniform growth.
  2. Gently squeeze them to remove trapped debris and refresh their shape.

It’s that easy!

Marimo Moss Balls with Shrimp

Marimo Moss Balls & Shrimp

Marimo Moss Balls make an excellent addition to shrimp tanks. They provide a natural grazing surface and a place for shrimp to hide.

Shrimp are natural scavengers, always on the lookout for bits of food and biofilm which the Moss Balls have plenty of.

Shrimp species like Cherry Shrimp, Amano Shrimp, and Ghost Shrimp all love hanging out on these cute little balls.

Marimo Moss Balls in aquarium

How to Propagate

I bet you didn’t know you can make more Marimo Moss Balls and it’s easy! Follow these steps to create more balls for your aquarium:

  1. Gently remove the Marimo Moss Ball from your aquarium.
  2. With clean hands, carefully split the moss ball into smaller sections, ensuring each section has enough algae to form a new ball.
  3. Roll the sections between your palms to create a spherical shape.
  4. Place the new Marimo Moss Balls back into the aquarium, ensuring they have enough space to grow.
Marimo Moss Balls with Snail

Tank Mates and Compatibility

Marimo Moss Balls get along with everything! No need to worry.

  1. Fish: Tetras, Guppies, Mollies, Platies, Rasboras, and Betta fish can all coexist peacefully with these furry green balls.
  2. Invertebrates: Shrimp and snails will benefit from from moss Balls, as they provide large grazing surfaces for biofilm as well as hiding spots.
  3. Other freshwater plants: Since they grow so slowly, they don’t compete with other plants for nutrients.
Various Sizes Marimo Moss Balls

Marimo Moss Balls – Final Thoughts

There’s no denying that Marimo Moss Balls are a beautiful addition to any freshwater aquarium, providing numerous benefits and requiring minimal maintenance.

They are compatible with a wide range of aquatic species and can enhance the aesthetics of your tank. By following proper care instructions in this guide, you can enjoy these fascinating little balls in your aquarium for years.

Marimo Moss Balls with Crayfish


Are Marimo Moss Balls suitable for all types of aquariums?

Marimo Moss Balls are best for freshwater aquariums with a temperature range of 68-77°F (20-25°C). They may not thrive in warmer tropical aquariums or saltwater tanks.

Do Marimo Moss Balls require a specific type of lighting?

No, Marimo Moss Balls can adapt to a wide range of lighting conditions, from low to moderate. However, exposure to direct sunlight for extended periods can cause them to turn brown.

How long do Marimo Moss Balls live?

With proper care, Marimo Moss Balls can live for many years, even up to a century in some cases.

How much can a Marimo Moss Balls grow in one year?

Marimo Moss Balls grow pretty slowly, usually around 0.2 inches (or 5 millimetres) per year.

Can I keep Marimo Moss Balls with goldfish?

While it’s possible to keep Marimo Moss Balls with goldfish, it’s essential to monitor them closely, as some goldfish may find them appetizing and nibble on them.  

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