Huh? Really? Souvenir marimo balls?!

This is an introduction to the marimo balls you often see sold in bottles at souvenir shops on Lake Akan!

What are man-made marimo balls?

While they are cultivated from the same species as authentic marimo balls (Aegagropila linnaei), they did not grow naturally in a lake, so they are called cultivated marimo balls. They are shaped into balls by people, so they are also called man-made marimo balls.

The marimo balls sold at souvenir shops in the Lake Akan hot spring district are not actually marimo balls grown in Lake Akan, but rather algae harvested from other lakes than Lake Akan that are cultivated and grown, then rolled into balls by hand.
The ones sold as “cultivated marimo balls” were originally harvested from Lake Shirarutoro, cultivated, grown, and collected, then rolled into balls by hand. The reason for creating hand-rolled marimo balls is reputedly to prevent illegal harvesting of marimo balls from Lake Akan.

How to grow a souvenir marimo ball

If you are sealing the container a marimo ball is placed in, leave a little air instead of filling it to the top. Marimo balls use photosynthesis, so they need carbon dioxide.
Avoid placing them in direct sunlight. Marimo balls do not tolerate heat well, so please keep the water temperature below 25°.
Change the water roughly every 1-2 weeks. Tap water is fine.
Avoid placing them in an area that receives no light at all. Light is required for photosynthesis.
If they are placed in the same tank as herbivorous fish, etc., they may be eaten, so grow them a container separate from other animals or plants.　


When you buy them from a souvenir shop, you may receive growing instructions. They may also be printed on the bag.

Where can I buy marimo balls?

Many cultivated marimo balls are sold at souvenir shops in the Lake Akan hot spring district. These days, they can also be purchased from online stores as well.

Why not try growing marimo balls as interior decoration?
Marimo balls do not need careful water quality management or feeding, and take almost no work at all grow, so they are perfect for everyday relaxation. There are also no concerns about lifespan, so you can make them a long-term part of your life.