A Marimo moss ball is a cylindrical type of algae. They are very slow-growing. They grow about 5 mm a year. They can last for 100 years. In the wild, they can grow to as much is 12 inches in diameter. They are found in the northern parts of Japan in colder waters. That is the reason why a lot of people have a hard time keeping them. They are actually cold water algae. That’s why they don’t always do well in tropical fish tanks because the water is too warm. They prefer the water to be cold. You should always use filtered water. Do not put them in direct sunlight. They do not do well in direct sunlight. Keeping them in direct sunlight will cause them to turn brown. They will also turn brown if the water is too warm.
I keep mine in a small bowl, and change the water every week or so. It’s also a good idea to stir the water every day with a wooden stick so that it will keep its round shape. In nature, it is moved by the ocean current, but since there is no current in your tank, you need to move it around every so often. It’s also a good idea to take it out and clean it every week, and squeeze it, and roll it around with your hands so I it will keep it’s shape. I have also heard that people take them out of the tank, and give them a good cleaning in a Tupperware bin. Then they stick them in some dechlorinated water, and put them in the refrigerator for twenty-four hours. It’s really good for them, and makes them look really green. Another thing that I read online is that some people put in a little aquarium salt.
Marimos are the ultimate low maintenance pet. They are cute, and fun to play with, but require very little care. They make a great first pet for a child. If you do a search on YouTube you will find lots of videos about them.