Me and my Marimos


Marimo Moss Ball is actually a type of algae scientifically called Aegagropila linnaei in 1843… subsequently renamed as Cladophora aegagropila in 1849 but in 2002 it was returned to its original name of Aegagropila linnaei after extensive DNA research proved it’s not a true Cladophora…

In Japan, these little fellows are only to be found at Lake Akan, Hokkaido and were declared National Treasures by the Japanese. A huge publicity exercise immortalised them as Marimo Moss balls although the algae can also be found in Europe, USA and Russia so don’t get too worried that you are getting a “fake” Marimo Moss ball if you buy yours from these countries.

It is a bit difficult for me to explain why I love these little balls of algae so much. Perhaps it is the gentle spherical huggable form they have or the lush green they wear (at times with pearls of airbubbles as accessories).


I had placed a large order for Marimos from Europe and while waiting for their arrival, I read up on their growing conditions, places of origin, basically whatever I could find on Marimo Balls. There wasn’t a whole lot of write-up on the Web but enough to give a general idea on the dos and don’t.

I prepared a big tank where Malayan shrimps were placed to provide some nutrients in the form of their waste products and to clean up the Marimos. Good companion fishes would be the guppy and Bettas as they don’t eat the moss.

There is a filter pump that provides a constant and firm current of water pushing against the Marimos. The current is not so strong that the shrimps are swirled every which way but strong enough to provide some sort of resistance or pressure needed to encourage growth.

Here are some pictures of my little darlings.

In the tank relaxing after their long journey. They arrived on 23 February 2007:

There were some big ones as well:

Tuffy arrived a little worse for wear but is a whole lot better now.

After some time, the balls will collect debris (they are sometime called debris magnets). You clean them by wringing them out gently like a sponge in clean water and dump them back to their tanks.

When they first arrived, the bottom of my sink was covered with sand after I finished gently wringing them out.

Here they are on my bathroom countertop after their bath:



The Experiment

I split a slightly smashed big 2.75 inch Marimo into 16 pieces. I had originally planned to split it into 8 or 10 but as I continued to split them into thumb-sized bits, I ended up with 16 pieces. The interior was slightly “gunky”.


These were placed into a white plastic fruit basket together with 4 other balls too irregular in shape to be a normal ball. The basket lid was tied on and placed in a huge fish tank which has been converted into a water storage tank in Punggol Coral Community Garden.


The Marimo bits stayed in the water storage tank for about 2 months. The green water problem we had in the water tank was not much of a problem during this time.

After 2 months (25 April 2007), I decided to take them back home as they didn’t look as though they grew and were not looking very well – they turned from a nice dark green to olive green. The water in the water storage tank proved too warm for them and they had too much bright light. Upon closer inspection, I discovered that their texture had become courser and denser then when I first split them up.

The bits spent 5 weeks in their own tank in a cooler environment (when I put my hand in the tank, it feels cool) and have slowly resumed their dark green colouring. They had also started to take on a more spherical shape. It is not a huge change in shape but you know that they are rounding off in shape.

It’ll be a while before they will look like the mummy Marimo. Stay tuned for a further update in December 2007.


Given the right conditions, the big Marimo balls will grow very big and may have to be split into smaller Marimos. I’ve read about an aquarium owner who used a Marimo to control the algae problem in his tank. The Marimo grew to the size of a grapefruit.

After some time, you might notice that your big Marimo is slowly producing a lump. That is a baby Marimo. It can be slowly worked out of the mummy Marimo. This might leave a big hole in the mummy Marimo. If you don’t want to wait for new Marimos to be produced this way, you can split the mummy Marimo into little balls like I did and wait for them to grow into cute little green spheres looking just like mummy.


Author’s Note: The above article in its entirety can be found at Green Culture Singapore forum.


66 responses to “Me and my Marimos

  1. Great site and a lot of help if in no other way but in encouragement. I would like to leave a tad of info for those who aren’t going to be putting their Marimo in a fish tank thus maybe harming their Marimo with water chemicals. Most people are aware on how to remove chlorine from their water, but many may not know that some cities, such as mine, are using chloramine. So if you set water out waiting for the chlorine to dissapte, it will, but a secondary Marimo killer will exist. Ammonia. Because chlorine dissapates quickly, water treatment plants added ammonia with the chlorine so our drinking water is ‘better’ for us – thank goodness we drink filterd water! Check with your local water treatment plant. You can buy a product in a pet store that will remove both. My order of 8 Marimo just arrived last week and I can so understand your fascination for these little cute…hence I’m online a lot trying to read all I can to give them the best life I can. Thanks again for your input.

  2. Hi Breeze. Thanks for putting in your comments. I really appreciate any feedback and information.

    I’m excited to hear of your Marimos’ arrival. They are little darlings, aren’t they?

    Keep in touch.

  3. I’m planning a trip to Hokkaido and I would like to get some marimo for a marimo-lover I know. I’ll be taking an airplane there and back and I doubt they’ll let me take a tank of water on with me. How long can the marimo last out of water?

  4. hi Lisa

    My Marimos came in a ziplock in an envelope with the water squeezed out of them. They were damp. I think they travelled for about a week in that ziplock before they arrived at my doorstep. Make sure your container for the marimos is sturdy. Some of my marimos were squished out of shape upon arrival. Have a great trip in Kokkaido!

  5. Hello Lisa,
    I brought some back from Japan a couple of years ago. They live in a jar on the kitchen window shelf. They have not grown at all, I change the water weekly and add some very mild fertilizer. Maybe too much light and water too warm? Bigger container needed? Thanks for any advice

  6. QUOTE: “…a secondary Marimo killer will exist. Ammonia”

    Untrue, ammonia could not possible harm marimo becasue marimo is clado algae, algae thrives on fish waste ie ammonia, nitate, nitrite, phosphates, etc.

    Chloramine is a different substance entirely, formed by ammonia and chloric acid.

  7. Victoria Felix

    Dear Velvetwriter,

    I just bought my first marimo balls. Package deal of three, but oh my goodness the shape they were in, literary. One might have been shaped okay but number 2 wow; number 3 was so out of shape it looked like a tore up piece of flat sod. My son, Tim and I tried for the longest time to reshape them so they could roll around easier at the bottom of the glass container. Please tell me is there a special trick to reshape these little Algae-Mos? Vik:)

  8. Hi Victoria

    First of all, congrats on getting your Marimos. Second, I’m afraid I don’t know any special tricks to reshape Flatty. Perhaps you might consider doing what I did to a slightly mashed up Marimo – break it up and see if it grows. If not, just let it be. Wait, here’s a crazy idea. Take some fishing line and tie up the marimos to hold it together. Give it some time, actually, a lot of time to see if they are able to pull themselves together. Good Luck!

  9. hi velvet writer,

    i ordered 1 marimo to singapore ;D
    and they have not arrived yet
    but i had no idea how to take care of marimo
    have some tips , dos and donts to teach me?

    thnak you

  10. Oh No!

    My baby split!
    I just got it and put it in some purified water and left it in for an hour.
    Then I came back and there were 3 massive dents all the way to the midde!
    The middle was a little bit hollow.
    It didn’t look good so I picked up the Marimo and it fell into 3 pieces……………………………..
    Each piece is a bit bigger than and inch.
    The pieces are not round but in a cone shape.
    Will it grow into smaller round piece and how long will it take if I have a crustecean inside the tank that creates a heap load of Co2 ?

  11. I recently became a Marimo Owner! These little guys are quite expensive(either that or I’ve been ripped off. 😛 ) !

    When I put them in water for the f irst time, all of them were floating. I figured that they would sink by the next day.

    The next day, 4 of the 7 had sunk. All of these four were small ones. The big ones(3-4 inches) were the ones that refused to sink.

    I kept wondering why they wouldn’t sink naturally. So I figured out how to make them sink by force.

    Treat the floating marimo like a sponge! Submerge them in water & squeeze gently(just enough for the marimo to soak up maximum water) You’ll see as you squeeze that many air bubbles will pop out.(That’s what caused it to float in the first place!) Then, when the marimo is fully absorbed water, let it go. The marimo will sink to the bottom of your tank! Voilla!


    Do you know of any cheaper online places to buy marimo? I bought them at “”

    I got 7 of them for 50 USD. (5 of them were 2 inches big, 2 of them were 4 inches big) They were only supposed to give me 6, but I got a bonus one too.

    Are marimo really that expensive? 😦 I want more, but I don’t wanna go broke. Lol!


    I really like this page! It was helpful! There are hardly any Marimo fans on the web! 😦


    • I think 50$ was way to high! I got my balls at Hokkaido (authentic!) and I got 2 for about 450yen, which is about $3.70. They were the smallest ones but I thought it will be fun growing them from a small size 🙂

  12. OK, I just got my first Marimo ball, quite by accident actually but now I find myself smitten with the little things! I was given several aquariums and one was live with fish and the Marimo. I really don’t know much about it other that what I have read on the net. I have been reading everything I can find but there isn’t much and alot of the info is pretty contradictory. I was just wondering where I could by more giant Marino or as I have been putting it enormus marimo. Everywhere I have looked they are called giant but they are approx. 1.5-2 inches diameter, the one I have is about 6 inches in diameter so I am looking for something comparable. Thanks!

  13. Hi Kay

    Six inches is from the tip of my middle finger to my wrist. That is one enormous baby you’ve gotten yourself! In the third photo above (the one where I have two big marimos in my hand), that is the size of the large ones. I don’t know where you can get another gigante but I am very sure there are some out there. Good luck.

  14. wat water to use?thks all the info!

  15. It’s been a year and all the Marimo are doing fine. They get their water changed once a week and a complete bath everytwo months. A bath consisting of putting them into clean and treated water then giving them gentle squeezes to empty out their tummies of too much gunk they may have acquired. My eight have turned into 7 with one becoming 24! So now I have a nursery container for all the wee ones – which by the way are adorable! In the year I had them I started worrying about nutrition for them, after all they are living. With a bit of research on nutrients in water etc. I found a hydroponics fertilizer and every two weeks add one drop in the nursery and two in the adults container – the adults being quite large. They became greener within a couple of months and appear very healthy, solid to the touch and very heavy – the big ones at least the babes range from chickpea to giant marble size. I hope this encuorages anyone who may be having a bit of trouble with their Marimo and just need reassurance on ‘how to’ or ‘can I’ Always remember, keep them cool to cold, bright room but no direct sun at all. If in summer your temperatures soar – put them into the fridge for a few hours each day or you may find them becoming ill and they don’t always recover.

  16. I want a marimo really bad! Like I need to get one, I went to Japan but I wasn’t able to find any while I was there, so I’ll have to order some! Omg, I’m so obsessed with marimo! Yay!

  17. Hi, i recently bought 6 from eBay.The problem is that after a month, some minor part of these marimo started to turn white and then to brown. I dunno what is the problem.Could it because of insufficient of nutrient since i always make sure the water is cool enough and provide enough light. Can anyone help me to solve it?

  18. I hope your marimo are doing well. I have just been given a marimo about 2 inches in diameter. I love it already, with the little bubbles!!

    Thank you for writing this and providing so many pictures and tips

  19. yooo !! well got my 2nd marimoo , and keep him in a big jar .i added a little bit of multi purpose organic fertiliser (it said to be fish safe on the label) a week later , i saw a unusual string of green hair growing out of him,the nd week the long green hair split into 4 branchat the tip and now each branch again splitinto 2 and 3 branch , can any one tell me what’s happening to my boy ???
    b.t.w kyoko i think is the chlorine in the tap water thats bleaching your baby hair white

  20. I’ve had my Marimo for about a year now, and its starting to break apart and getting a dirty layer of olive green on its surface even though I’m changing the water and giving it a small bath. I’m suspecting the cold temperature of my dorm room might be affecting it. What are the optimum temperatures for marimo to grow in?

    • Hi Finny,

      Sorry for the delay in response. Is your Marimo getting any sunlight?


      • Its quite alright. Its currently getting indirect sun light on a window sill. Its a north window, so it doesn’t get much direct sun light unless its around sun set.

  21. dear velvet,
    Hi! Recently i just bought marimos from singapore and bring it back to Indonesia.

    I’m concerned about the weather in Indonesia and I put my marimo with bio-disc water. (They claimed the plant will grow greener and better with bio-disc)

    Any tips for a beginner marimo carer?! And I notice you also sell marimo. Can you ship it to Indonesia?

    Thanks! Waiting for your answer soon!

  22. hey, surfing 1 mins on site and have to say we have here
    interesting site and I’m gonna like it.

    look forward to surfing around and reading alot of topics here.

    figured I say what’s up!

  23. hello everyone,
    I bought my first marimo 3days ago. It was soo cute that I couldnt resist. I think it was a little expensive I bought it 8$canadian for a small (3centimeter)

    I putted in my 32gallon fish tank(will have to buy more large marimo and cant find one in the pet shop) with goldfish. will the fish eat my marimo?

    and I made ALOT of research and readings about marimo, is it true that there are fake marimo?

    how long do I have to wait before spliting a marimo?


    • Marimo is an algae, and goldfish are notorious for eating algae, I wouldn’t put it with goldfish or any fish that fests on algae. I have mine with my betta fish, since he’s carnivorous, he uses it as his resting post.

  24. Hello,

    Found your website when looking for information for marimos.

    I recently start my shrimp tank and want to put some marimos in it. I was lucky enough to get 4 of them at my LFS. 😀

    One of them has brown face 😦 on when I got him. He has been in my tank for 2 weeks now and he seems getting better…. maybe just me thinking…

    One of them fell apart…. he became 5 pieces. I am a bit worried about them…. 😐

    I have a breeding net in my goldfish tank. I may put the babies in it so they can get alot of nutrient (hopefully).

    Thank you for having this website.

    We really should have a Marimo lover group!!!! 😀

    • Hi Xeno. I hope you get many little ones

      I agree with you on the Marimo lover group but I am too busy to start one!

  25. Hi. Thanks for the info! This now seems to be one of the most informative Marimo Ball sites on the net. I recently got a Marimo from my local pet chain store and am infatuated. Being an engineer I had to figure out a way to get more, better, faster so I built a small circular tank to keep the little guys in motion. Just do a search for “marimo factory” on youtube.

    • Hi Robotguy. Those are nifty gadgets. The second one looks like a marimo ball racetrack. Keep up the good work! Everyone else, keep sharing your marimo moments.

  26. i forget to tell, that i live in tropical country. my room temperature is 25-28 celcius, my marimo comes from local store,so i don’t think it has temperature shock

    • Hi there

      Sounds like an injury. The patch could be dying. If the brownish area goes through to the centre and the ball is “loose”, there might not be any hope. Leave it for a while (which I’m sure you have been) in cool bright shade area. Good luck.

      Sorry I couldn’t be much of a hope.


  27. Diana Gunawan

    I just bought my lovely Marimos today…
    They come with the jar and sands….
    I wonder if I need to clean the sands and open the lid?
    Do they need gases exchanged (e.g. oxygen)? or they could survive in closed jar?


    • Hi Diana

      Congrats. Yes, you do have to rinse the sand. Marimos are dirt magnets. They can survive in the jar. You can open the jar if that makes you feel better but please keep an eye on the water level.


  28. I have a marimo ball 1/2″ that was healthy until hid started to have this weird grayish brownish thing on it!!! I’m not sure if its sick, but is there any way I can heal them?

  29. where did u buy the marimo from?..

  30. Hi everyone,
    Got my marimos a couple of weeks ago, and they seem to be ok. I initially put them in tap water, but they are now in filtered water. They get no direct sunlight.
    However, small filaments of the algae are coming off the balls. What causes this? Do they need nutrient supplements?

    Also is it normal for them to remain constantly at the bottom of the container? I’ve heard they will move up and down, but I haven’t seen that happen.

  31. I have been keeping my marimo in a 1 gallon glass cylinder in a sunny window, next to my workspace ,cleaning them once a week, and replacing the water with a pinch of sea salt and a few drops of aquatic plant food. Every single one, from 2″ to 5″ have grown considerably and seem very happy. I have also coaxed out some protruding “babies”, and have them in a 1 quart nursery, in which I create a whirlpool several times a day with a chopstick, to simulate wave movement. These too, have been growing quickly. I’m sure it’s obvious that I am in love with marimo. I also heard that they have developed a magenta colored marimo in the Netherlands. Now I’m fantasizing about having red and green together. Christmas Marimo!

  32. Recently set up a small tank with several Marimo Moss Balls. Would it be good to add a few small guppies? Thinking maybe the guppy “poop” would be good food for the Marimo balls.
    What would you suggest I ‘feed’ the Marimo?

    Thanks for any help,

    • Hi. As long as the fishes have small mouths and won’t chomp up the marimbas, that will be fine. The Marimos will “feed” on the fish poop but don’t forget that Marimos are gunk magnets and you will have to clean them out periodically.

  33. Hi I just figured out if you rinse your marimo under water then tap it with one finger and roll it between your hands into a into a circle it holds it’s shape!!!!!
    Good luck!

  34. Where did you get yours I am getting my babies on ebay I am getting 3 very small I ordered a perment home for them and I have pink flat on one side marbles if you know what I mean. I am really excited to get them Huey, Duey and Luey I like to name my pets and how they act & everything that was all I need to hear. Being Disabled and have to take care of them is easy compared to my beautiful puppies one being my Service Dog.and it will be on my coffee table table so I can watch them and meditate.
    How often do you do the salt and do you clean it out right after? I want to make sure I am the best taken.
    Thank you so much for the information I plan or reading the rest of them too.
    Marsha and Daisy Mae SD.

    • Hi. I got them via ebay and locally through the aquariums. Cute names. I don’t salt mine but perhaps others do. I clean them out when they get gunky.

  35. Hi Stevebudbwl,
    Thank you for all your information it was wonderful is it only when I change the water that I give the pitch of sea salt and a few drops of aquatic plant food. Loved the information on the nursery thank you for all the valueable information. I hope they or whoever allow me to join here so much information’

  36. Hi everyone. I recently found marimos on an etsy shop and I was wanting to get some information about them before I got one. This site really helped. I will follow this and put in some information about my marimo once it arrives 🙂
    I cant wait!

  37. Hello, I’ve been looking for someone who might be able to give me some advice on what I can do about my sick marimo. There is so much conflicting information out there, I have no idea what to do! My marimo are a light olive green color and they have a rotten egg smell. I give them clean water and a light squeezing regularly but I worry that I might be making it worse by disturbing them too much. One person recommended that I give them more light, but then I recently found out that our tap water contains chlorine and ammonia (which I guess turns chlorine into chloramine, I don’t know what the difference is as far as the marimo are concerned). So now I have no idea what’s made them sick. I thought about trying the water from our dehumidifier instead, it doesn’t seem to hurt any of our houseplants. Any advice would be much appreciated!

    • Hi. Apologies for the late reply. Hope your Marimos made it. Do you have them in some sunlight or none at all? Some of mine turned greyish when they didn’t have enough sunlight. I don’t clean them that often, perhaps once every four five months. Please update.

  38. I just got a marimo from a pet store really cheap and it’s more oval than spherical, it’s only about 1 inch tall and 2 inches wide so i don’t think it has a baby but when cleaning it i noticed a distinct line near the middle that makes it seem like part of it is a lump. I tried to tap it into shape but to no avail (as it is my first and only marimo I’m afraid to use too much force). It is in the equivalent of a large clear cup (what the pet store sold them in) and I change the water once a week. Is my marimo okay? Should I try to remove the lump or leave it to see what happens? It looks healthy green color but it hasn’t moved at all (I heard that they move around a little), I keep it at room temperature and only put it in cold water but it’s tap water and an above post said something about harmful chemicals? Basically I’m just worried I’m doing something wrong and it’s going to die; could you tell me if I’m paranoid or if there’s something i should change? Thank you.

    • Hi. Don’t fret about it. I haven’t seen mine move except up and down due to the air bubbles. Leave your tap water out and uncovered overnight. If you can, use well or rain water.

  39. Hihi, r u staying at Punggol grove? Just shifted to Sapphire n am looking for some marimos to keep with my betas. Do u still sell then? Look forward to ur email! 🙂

    • Hi. No, I don’t stay at Punggol Grove. Sorry, don’t sell them any more but do check out the fish shops at Serangoon and Clementi. Or check out Ebay.

      AND sorry for the late reply. Crazy crazy, tiring time…

  40. Hi Velvet, firstly- thanks for putting together this wonderful site, it’s been the best source of marimo info I’ve found on the web! I hope my post is of good use to other marimo fans- I asked in my local fish shop about cutting my large ball into smaller ones, and the advice I was given was to cut it outside my fish tank and to rinse it thoroughly before putting it back in. The reason being that any tiny fragments drifting off would anchor to any wood and decorations, look like an unsightly flat algae and be very difficult to clean up. I’m not sure if that’s a bad thing but thought I should mention it anyway! Keep up the good work and thanks again!


  41. Hi, I am new to this forum but really love Marimos they are so cute! I saw them many years ago when I was in Japan but didn’t buy them because the shopkeeper told me they need cool water like 15 deg C below. I live in Singapore, it is warm here. I really want some though… Can they survive the climate of 28 deg C ? Also where can I get them in Singapore ?

    • Hi! Welcome to the Wonderful World of Marimos! My marimos are in the office at 23C but not getting a lot of sunlight so they are kinda poorly right now. Aclimatise them first. You can get them at fish shops at Serangoon and Clementi. Good luck! They are absolutely wonderful as ice breakers in the office.

  42. Hi, I just stopped by to learn about this place. It
    seems to be really cool and I enjoyed browsing it, thank you for
    the helpful stuff!

  43. So rainwater or distilled water is good for marimo?

  44. I use rainwater, SO much better than tap water. They LOVE rainwater, versus tap water from the faucet.

  45. Can I change water for marimo every day?😕

  46. I found these in the UK 3 – 4 inches in diameter for £1.99 – very cheap I thought!

    I live in Gibraltar and they cost £4.50 for a 1.5 – 2 inch diameter ball here…

    I bought 2 of the UK balls but wasn’t sure if I can fly back with them. Will security let me through with them if the liquid is squeezed out?

    • Hi Miss Cellany

      Sorry for late reply. I don’t see it as an issue but the Customs officers might not think the same. Just tell them these are decorations which in a way is true – decor for the tank.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s