Marimo moss balls are easy to care for. Making a beautiful terrarium (or aquarium) for Marimos is fun and doesn’t take much time. We will go over all the tips and design tricks you will need to know in today’s post.


What Is A Marimo?

Native to Japan, Marimo moss balls are a filamentous form of algae found at the bottom of fresh water lakes and rivers. Marimos form a velvet-like nearly perfect sphere of green with a moss-type appearance.

In Japanese, the term Marimo means “ball of seaweed”.  Marimo moss balls are typically kept in aquariums. In fact, they are one of the most popular living aquarium plants in the world.

Some people keep Marimos as “pets” and believe it or not, even have names for them!

However you keep your Marimo, they always look great on a patio table or a desk top.

Materials You Will Need

For a nice looking terrarium you only need a few items:

  • At least 2 Marimo moss balls
  • A glass terrarium, mason jar, or a glass vase
  • Smooth sea glass gravel (looks best after dark with lighted terrariums), small black river pebbles, or colored sand
  • Tap water at room temperature
  • Lights (optional, see ‘Kits’ below)

Where To Find Marimo

Marimo moss balls are easy enough to find online and in some stores such as pet stores or aquarium stores that stock live aquatic plants. Online they can be found in the usual places like Ebay, Amazon, and Etsy.

They will likely arrive small but this is good for smaller terrariums. Some sellers have packages with an assortment of sizes. The typical cost online for a few Marimos is around $6.oo not including shipping.

Care & Maintenance

Marimo are very slow growers with a life span of up to 100 years eventually reaching a foot across! Don’t worry, your Marimo will be small when you purchase (or divide) them and they only grow around 5 millimeters per year.

Normal household light or indirect sunlight is preferred. Marimo moss balls will thrive in tap water at room temperature, change the water every 1-2 weeks.

Roll your moss ball around on occasion to keep it’s round shape and all sides green including the bottom. Marimos are moved around the bottom of river beds and lakes in their natural environments, so they won’t mind if you play with them at all.

Adding Animal Life Together With Moss Balls

Growing plants inside an enclosed glass ecosystem makes a terrarium. When you add animal life, you have an instant aquarium!

Marimo moss balls grow by absorbing nitrates, phosphates, and other organic waste from the water. Consuming animal waste in the water makes them perfect companions for fish.

Betta fish and tiger shrimp are great companion additions to marimo aquariums. Bettas and tiger shrimp both come in beautiful colors including almost every color of the rainbow. They also prefer fresh water environments.

I had not considered having any kind of shrimp in a small indoor water garden until I started seeing these things online during my research into everything marimo. Choose a glass container from around 1 Liter to a half gallon or larger for fish and shrimp. Goldfish might need up to at least a gallon size or larger.

Buying A Starter Kit

If you would prefer your terrarium/aquarium to have lights, then purchasing a battery operated or solar kit is the way you want to go. Some kits are sold just for this purpose and others you may see online are sold to make bottle or jar lights.

You can use the bottle and jar light sets if you adhere the light string to the bottle cap/jar lid part of the kits that they are connected to. Super glue or a hot glue gun will work well for this.

The opening of the glass container you choose should be considered. The hole needs to be large enough to insert the marimo, other materials, and occasionally a cleaning brush inside it.

Resource Links (from Amazon)

Solar mason jar lighted lids for standard sized mason jars

Lighted round glass terrarium kit (pictured above)

Lighted straight vase terrarium kit

Live Marimo moss balls (set of 5)

Blue velvet shrimp, they also come in Red and Yellow, among other colors.

Rounded sea glass (3-5 mm)