Health Problems of Marimo Balls: Color Indicators

Health Problems of Marimo Balls: Color Indicators

The Universal Popularity of Marimo:

Marimo’s popularity stems not only from their unique round shape, but the fact that they are also incredibly simple to care for and can live for nearly a hundred years. They have decorative value, both in aquariums or on their own in vases. Marimo will rise, sink, and roll around in the container it is placed in. While these movements are only a response to the levels of light a Marimo is exposed to; many owners compare them to fish – only with less maintenance required!

What Type Of Environment Do Marimo Require?

A Container: The size of a Marimo’s tank depends on how big you want it to be and how many Marimo you are keeping. Since Marimo do not require filtered water, they can be kept in just about any type of container from small sealed bottles to traditional fish tanks. If you are caring for a larger colony of Marimo, you can keep them in tanks where they are close to or touching one another without any issues.

Water: Marimo require water to survive, but do not require any specific water purification. This means that they can survive in most types of water from tap water to mildly salty water and anything in between. Marimo thrive best in cooler water, so ideally you should ensure that the water they are being kept in is between 54 and 68 degrees Fahrenheit (12 and 20 degrees Celsius).

Indirect Sunlight Only: A Marimo’s tank should be kept away from direct sunlight; they come from a lake bottom environment where they are exposed only to what little sunlight filters through the lake’s waters. If your Marimo are exposed to direct sunlight for an extended period they will die.

Weekly Water Changes: Your Marimo’s water should be changed an average of once per week. Some owners prefer to change only a quarter of the water in a tank at a time, while others opt to change the water entirely. Both of these options are acceptable and any water removed from your tank can be replaced with tap water. Weekly water changing doesn’t take much time and will allow your Marimo to stay clean and healthy.

Weekly Cleaning: When you are cleaning Marimo’s water, you should also take the time to individually clean each Marimo as well. In order to clean a Marimo, you should put it in a container with clean water and gently squish it, while also rolling it in your hands. Regular cleaning will get rid of any dirt clinging to the Marimo while also keeping it healthy and helping it to maintain its round shape.

Can Marimo Have Health Problems:

Like any other plant or animal, Marimo do suffer from health problems and will occasionally require treatment. Thankfully, Marimo health problems are usually simple and easy to treat.

Healthy marimo balls will be bright green. Variations in color may indicate the water is too warm or not clean enough, or the light is not optimal. A lighter or white color could mean they are getting too much light. If the balls turn brown or grey, they likely need to be cleaned. Do this and gently rotate them in the tank so any brown spots are facing the light source. A small amount of salt, up to 5 percent of total water volume, can be added to the tank to encourage growth, if it will not affect other plants and animals. Alternatively, discolored Marimo balls can be placed in a bowl with a 5 percent salt water solution and ice cubes for two to three hours. Black spots are usually not a good sign. You can try cutting them out, then gently washing and re-shaping the ball.

Here are some common Marimo health problems and how to resolve them:

Brown spots should first be dealt with by gently cleaning the afflicted Marimo. If cleaning does not solve the problem, you should remove the spots by pulling them off and then putting some salt in the Marimo’s water to stimulate growth. If the brown spots are mostly on the bottom of your Marimo, it may be an indication that it isn’t getting enough light on its underside. You should take the time to change the Marimo’s position yourself every few days to ensure all sides are getting enough light.

Turning white can indicate that a Marimo is being exposed to too much light and has begun to die. You can reverse this process by moving it to a location with less light and no direct sunlight.

Turning black and beginning to fall apart are signs that a Marimo has begun to decay internally. The best way to combat this problem is to remove all of the visibly black areas and then rolling the Marimo back into its original shape. Though this will reduce the size of your Marimo, it will usually begin to grow again once the dead parts are removed.

Slimy white spots are a harmful form of algae that can prey upon Marimo. If you notice this type of spots on your Marimo you should put it in a container with clean water and wash off the white spots, or alternately pull off the spots with tweezers.

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Comments (19)

  • Noelle

    thank you so much! I’m worried about my moss balls and this helped a lot.

    May 21, 2020 at 9:42 pm
  • Ember

    My moss ball has begun falling apart and I am not able to put it back together. Please HELP!

    June 12, 2020 at 4:43 am
    • Oliver Gair

      Hey there, as this is a month late I hope it finds you well and I hope the problem was solved, but I would recommend pulling out the marrimo moss,Checking for And then dealing with discoloration as scripted above. I would then recommend propagating it, best way for moss in my opinion is cutting into two equal parts forming the ball with the half wrung out moss and tying two pieces of twine around vertically and horizontally to promote growth in the ball form. You can through them back in your aquarium,if there’s no discoloration your moss just is changing shapes and growing which is normal, the twine can still be used to keep a larger, healthy miss ball keep its shape. Hope to have helped or answered any unresolved queries!

      July 26, 2020 at 6:08 pm
      • Shade

        This could also mean parasites, which can usually be dealt with by putting the Marimo in chlorinated water for a while, than saline for a while.

        September 24, 2020 at 7:20 pm
        • Kingdom of Aquatics

          Can I use the moss ball and use it as a dry start on my rocks to cover my rocks as the same moss ball.

          December 16, 2020 at 2:55 pm
    • MossyJoe

      Try rolling it best you can then tie it criss cross or more times to hold it in place till it gets established.

      February 13, 2021 at 11:00 am
      • Dora Adams

        I have had a driftwood tree almost a year that i covered with moss balls. They are now very dark green and looking poorly What can I do to save them ?

        August 4, 2021 at 2:45 pm
  • Rapha

    Thank you so much for theses tips!
    Unfortunately, my moss balls were standing in the direct sun for too long and without a change of water either.
    They show some discoloration so I moved them away from direct sunlight and changed the water.
    The balls themselves don’t fall apart, but all the stones in my aquarium show some light green algae growth. I keep nothing but the marimos in there.
    Is this already some kind of dissolution?

    August 12, 2020 at 12:26 pm
    • Shade

      No, this likely means your marimo is doing well and spreading alagea to other parts of the tank.

      September 24, 2020 at 7:17 pm
    • Lauren maylon

      Sunlight on the tank will cause regular algae to grow, especially strong in direct sunlight.

      October 30, 2020 at 4:57 pm
  • Icarus

    Is there a way to treat a marimo that has turned brown from lack of water? I bought one of my marimos in a hurry because I saw that the store selling it did not place it in water, and it was turning brown. I put the brown marimo in a new tank with clean water just in case, and added some of the marimo food(?) that come with them. It supposedly includes nutrients like magnesium and calcium. On the first day I bought the brown marimo, it was floating instead of sinking to the bottom, and smelled of rotten eggs. After a day in water, the marimo sunk down, though its colors are still looking very bad. I am planning on trying the cleaning method as soon as I can, in case it helps the marimo. Are there any suggestions on what I can do to save this poor marimo?

    P.S. Though I am currently taking care of 3 marimos including the one I am talking about, I am still a very beginner on marimo caring, so please help!

    October 31, 2020 at 12:54 pm
    • MossyJoe

      I’d remove them and give them a good soak and rinse. Sulfur smell is not really a good sign. If the color doesn’t start to turn green and worsen you may need to trim the brown spots and re-roll the good part back into a ball. Or cut it in half if the smell and color doesn’t improve to see if it’s starting to rot on the inside.

      February 13, 2021 at 10:59 am
  • Ana

    I have two large Marimo’s that are on the greyish side, one of those two looks more grey than the other. The rest of my Marimo’s in the tank look great, nice and green. Are they just dying..? I take the time to clean them. Any chance in saving them?

    November 25, 2020 at 6:54 am
    • MossyJoe

      Provably too much light… If the others are doing okay, try putting the grey ones in that area.

      February 13, 2021 at 10:54 am
  • Jay

    I recently got a couple marimo moss balls, they have changed the colour of the water and I don’t know why, they look decently healthy considering the fact I got them of eBay but it is slightly concerning as I can’t find any information as to why this is happening or what I can do to stop the balls from changing the colour of the water. Thank you

    November 26, 2020 at 11:20 am
    • MossyJoe

      Did you wash them out repeatedly? After 3, 10m sessions of soak and squeeze mine still had a little brown water leaking out, now they’re in quarantine before adding to my tank to avoid that problem.

      February 13, 2021 at 10:52 am
  • Sarah

    this is very helpful. I am babysitting my friend’s Marimo because she couldn’t take it across the border and covid was like bleh so this helps. :) !

    November 29, 2020 at 6:20 am
  • Emma

    So I recently purchased mass balls from my local PetSmart about 3 weeks ago and I changed the water last Thursday but the water is already turning into a dirty look.

    January 20, 2021 at 12:49 am
    • Alicia Reid

      I have tiny pebbles coming out of one of my moss balls… They do not look like zebra mussels. There is a film floating around… I’m afraid of putting them in my fish tank. What can I do about the pebbles?

      April 16, 2021 at 12:47 am

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