Marimo Moss Balls: A Simple Care Guide

Marimo moss balls up close

At ome, we absolutely adore marimo moss.

It’s always one of the first things our customers point out at our Bristol shop, despite their being one of the smallest items on sale.

Their defining roundness, petiteness and luscious green glow make them indisputably ‘cute’.

This guide will be a clear, to-the-point look at how to take care of marimo moss balls.

Make sure to visit our more expansive guide to marimo moss balls for further information and help on where to buy marimo.

Read on, ball fans.

Quick Guide

  1. What is Marimo Moss?
    1. Marimo Growth Habits
    2. Benefits of Keeping Marimo Moss Balls
  2. Marimo Moss Care Guide
  3. FAQs

1 | What is Marimo Moss?

Marimo moss balls are unique aquatic plants that belong to the species Aegagropila linnaei.

Actually, a species of algae, Marimo moss balls are spherical in shape, resembling small, green, velvety balls.

They are native to freshwater lakes in cold regions such as Iceland, Scotland, Japan, and Estonia.

Marimo moss balls form naturally from the rolling action of water currents, which mould layers of algae into rounded shapes over time.

Due to their distinctive appearance and fascinating growth process, Marimo moss balls have become popular additions to freshwater aquariums and terrariums worldwide.

Enliven your living space with the tranquil elegance of a miniature aquarium filled with lush marimo moss, a captivating addition to your decor.

In the UK? Check out our Marimo Moss Aquariums

1.1 | Marimo Growth Habits

Marimo moss balls exhibit slow but steady growth under optimal conditions.

They grow by absorbing nutrients and carbon dioxide from the water through their surface, gradually increasing in size over the years.

While they can survive many water conditions, including low light and cooler temperatures, they thrive best in clean, well-aerated water with moderate to high lighting.

Marimo moss balls have the unique ability to photosynthesise both in low light and complete darkness, making them adaptable to various environments.

1.2 | The Benefits of Keeping Marimo Moss

  • Low maintenance: Marimo moss balls require minimal care and attention, making them ideal for busy individuals or beginners in the hobby.
  • Natural filtration: They help improve water quality by absorbing nitrates and other pollutants, promoting a healthier environment for aquatic life.
  • Debris removal: Marimo moss balls trap debris and detritus, acting as natural filters and reducing the need for frequent water changes in larger aquariums
  • Adaptability: They can thrive in various water conditions, including low light and cooler temperatures, making them versatile additions to aquariums and terrariums.
  • Aesthetically pleasing: Marimo moss balls add visual interest and natural beauty to aquatic environments, enhancing the overall appearance of aquariums and terrariums.
  • Unique appearance: Their spherical shape and velvety texture make them stand out among other aquatic plants, attracting hobbyists' and enthusiasts' attention and admiration.
  • Longevity: With proper care, Marimo moss balls can live for many years, providing enjoyment and beauty to their owners over an extended period.
  • Stress reduction: Observing the slow and steady growth of Marimo moss balls can have a calming and therapeutic effect, reducing stress and promoting relaxation for aquarium enthusiasts.
Mairmo moss balls in glass container

Marimo moss is one of the simplest plants to care for. 

2 | Marimo Moss Care Guide

Fortunately, Marimo moss is exceedingly simple to care for.

Following correct procedures should see you only having to make changes once or twice a month.


Marimo moss balls prefer indirect or low-light conditions.

Avoid placing them in direct sunlight, as this can lead to excessive algae growth and discolouration.

If kept in an aquarium, provide moderate to low lighting to simulate their natural habitat.

LED aquarium lights with adjustable brightness settings are ideal for maintaining optimal lighting conditions.


Marimo moss balls thrive in cooler water temperatures ranging from 65°F to 78°F (18°C to 25°C).

Avoid exposing them to extreme temperature fluctuations, as this can stress the plants and affect their health.

Maintain stable water temperatures within the recommended range to promote healthy growth and prevent temperature-related stress.

Close up of a marimo moss ball reproducing


Marimo moss balls require high humidity levels to thrive. In aquariums or paludariums, ensure adequate moisture levels by misting the moss balls regularly or placing them in an environment with high ambient humidity.

Avoid placing Marimo moss balls near sources of dry air, such as heaters or air vents, as this can lead to dehydration and browning of the plants.


Use clean, dechlorinated water when caring for Marimo moss balls.

Tap water should be treated with a water conditioner to remove chlorine and other harmful chemicals before use.

However, in lieu of purer water, tap water should be sufficient. Ensure to change the water regularly.

Studies have shown that Marimo moss in fact prefers an ever-so-slightly saline water solution.

Water Changes

Change the water in the aquarium or paludarium every 1 to 2 weeks to prevent the build-up of toxins and maintain water quality.

Regular water changes are essential for the health and well-being of Marimo moss balls.

Replace approximately 25% to 50% of the water in the aquarium or terrarium during each water change to maintain optimal water quality.

Use a siphon or aquarium vacuum to remove debris and waste from the substrate during water changes, ensuring a clean and healthy environment for the moss balls.

You can also rinse the Marimo moss balls under a tap, using your hands to gently squeeze out old water and maintain the ball-like shape.

Bulk marimo moss balls for sale

Marimo moss balls can be kept round by gentle rolling in your palm during water changes. 


Marimo moss balls derive nutrients from the water through photosynthesis and absorption.

While they do not require additional fertilisation, occasional feeding with a diluted liquid aquarium fertiliser can promote healthier growth and vibrant colouration.

Add a small amount of liquid fertiliser to the water during water changes, following the manufacturer's instructions for dosage and frequency.


Marimo moss balls propagate naturally by budding or splitting into smaller pieces called "baby Marimo" or "pups."

These pups can be gently separated from the parent moss ball and replanted to propagate new plants.

To propagate Marimo moss balls, gently pull apart the individual segments or pups and place them in a separate container with clean, dechlorinated water.

Provide suitable lighting and water conditions for the pups to encourage healthy growth and development.

Ball maintenance

Over time your Marimo moss balls may lose their ‘ball’ shape.

This shape is gained in the wild from rolling across the beds of lakes and rivers.

In a domestic setting you must periodically ‘roll’ the balls in your hands, gently, during water changes.

Bring a slice of aquatic serenity into your home with this adorable miniature aquarium featuring vibrant marimo moss balls, a delightful sight to behold

Marimo moss balls can be kept in a variety of containers, large or small - and can thrive even with tap water. Though, we would recommend distilled. 

3 | FAQs

Don’t see your question on the list? Leave a comment below and we’ll add it.

Can I keep Marimo moss balls with other aquatic plants?

Yes, Marimo moss balls can coexist with other aquatic plants in the same aquarium.

However, ensure that the other plants have similar water and lighting requirements to prevent competition for resources.

Do Marimo moss balls require fertilisation?

Marimo moss balls derive nutrients from the water and do not require fertilisation.

However, occasional feeding with a diluted liquid aquarium fertilizer can promote healthier growth.

How often should I clean Marimo moss balls?

Marimo moss balls should be gently rinsed under running water during regular water changes, typically every 1 to 2 weeks.

Do Marimo moss balls require pruning?

Marimo moss balls do not require pruning like other plants.

However, you can gently roll them between your palms to maintain their spherical shape and remove any accumulated debris.

Can I divide my Marimo moss ball into smaller pieces?

Yes, Marimo moss balls can be divided into smaller segments, known as "pups," which can then be replanted to propagate new plants.

Even without noticeable growth you can split your Marimo moss down into smallere balls.

How long do Marimo moss balls live?

With proper care, Marimo moss balls can live for many years and even decades.

Some specimens are reported to be over 100 years old.

Do Marimo moss balls float or sink?

During photosynthesis Marimo moss balls store more oxygen, making them float.

Typically marimo moss will sink to the bottom of their container.

They can also be permanently ‘anchored’ to surfaces using fixings or adhesives.

Can I keep Marimo moss balls in a cold-water aquarium?

Yes, Marimo moss balls can thrive in cold-water aquariums with temperatures ranging from 65°F to 78°F (18°C to 25°C).

What should I do if my Marimo moss ball turns brown?

Browning of Marimo moss balls can indicate poor water quality or inadequate lighting. Perform a water change and ensure proper lighting conditions to revive the moss ball's colour.

Are Marimo moss balls safe for fish and other aquatic pets?

Yes, Marimo moss balls are safe for fish and other aquatic pets. They provide natural filtration and help maintain water quality in aquariums.

Can I keep Marimo moss balls in a shrimp tank?

Yes, Marimo moss balls are compatible with shrimp and provide additional grazing surfaces and hiding spots.

Do Marimo moss balls require a special substrate?

Marimo moss balls do not require substrate and can be placed directly in the aquarium or terrarium.

However, a layer of sand or gravel can help anchor them to the bottom if desired.

Can I keep Marimo moss balls in brackish water?

In contrast to popular belief, Marimo moss can survive and even thrive in slightly brackish water.

How do I revive a dried-out Marimo moss ball?

Soak the dried-out Marimo moss ball in clean, dechlorinated water for several hours or overnight to rehydrate it.

Ensure proper water quality and lighting conditions to promote recovery.

Can I keep Marimo moss balls in a vase without filtration?

Yes, Marimo moss balls can survive in a vase without filtration, provided the water is changed regularly and proper care is taken to maintain water quality.

Are Marimo moss balls edible?

While Marimo moss balls are not toxic, they are not considered edible and should not be consumed by humans or animals.

Can I keep Marimo moss balls in a betta fish tank?

Yes, Marimo moss balls are compatible with betta fish and can provide natural enrichment and filtration in a betta tank.

Can I keep Marimo moss balls with snails?

Yes, Marimo moss balls are safe to keep with snails and can provide additional grazing surfaces and habitat for them.

How do I prevent algae growth on my Marimo moss balls?

Maintain proper water quality and lighting conditions, perform regular water changes, and avoid overfeeding to prevent algae growth on Marimo moss balls.

4 | Conclusion

There is a deeper world to that of the humble Marimo – but this guide provides the average owner with all the tools they’ll need to care for their Marimo moss balls.

If you have any questions or want to share a Marimo success story – please leave a comment below.

Otherwise  - check out our comprehensive terrarium plant care guide for a broader catalogue of information.


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