Marimo is a rare growth form of Aegagropila linnaei in which the algae grow into large green balls with a velvety appearance. The species can be found in a number of lakes and rivers in Japan and Northern Europe. Colonies of marimo balls are known to form in Japan and Iceland, but their population has been declining.
Marimo Moss Balls are one of our very favorite plant discoveries of the last few years. Marimo are equal parts bizarre and beautiful, and Marimo moss ball care is very easy.
Keep your Marimo where they will receive llow to medium indirect light. You must protect marimo from the direct rays of the sun, as Marimo can easily turn brown if they are getting direct light! Also keep in mind that direct sun will be intensified by glass marimo enclosures which can heat water quite quickly. Remember - these guys are native to cool lakes, and should be kept cool.
Marimo are well adapted to low light spaces and can photosynthesize in normal household light. If your space has no window, keep marimo close to a fluorescent or full-spectrum bulb.
Changing the Water
Change water once every two weeks using regular tap water (for best results, allow water to sit out for 24 hours prior to changing the water). You’ll need to change the water more often in summer, as it will heat and evaporate more quickly. Clean your marimo enclosure with a brush if algae begins to grow on tank surface.
If your marimo turn brown, make sure they’re moved to a cooler location with less direct light. They may recover and turn green again on their own. If not, you may add a tiny amount of aquarium ocean salt.
Why are my Marimo Balls Floating?
More than likely, your Marimo balls have an air bubble trapped inside that is causing them to float! Gently squeeze your marimo balls to pop the air bubble. Generally, Marimo will sink to the bottom of their tank within 1-2 days of being added to an enclosure.
Can Marimo Survive Outside of Water?
Yes! Marimo moss balls can survive without water if kept in plastic or a closed jar for several days, as long as they aren’t allowed to fully dry out. Plastic bags are the easiest way to travel with Marimo moss.
Keeping Marimo Shape Round
In their natural habitats, the waves and currents of the lakes gently rotate and roll the Marimo balls along the floor of the lake.
To ensure that Marimo stay keep their round form and don’t flatten out, you’ll want to gently agitate the water in your Marimo enclosure, with the goal that when your Marimo balls settle back to the bottom, they rest on a different side than they had prior. Try to simulate the gentle waves of a lake.
Marimo and Aquarium Safety
Many people ask us if Marimo can go into their fish tanks. We’re happy to report that Marimo are welcome additions to freshwater aquariums. In fact, they naturally absorb toxic nitrates in water and act like miniature filters, cleaning the water.
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.