Introduction: How to Take Care of Marimo Balls.

Picture of How to Take Care of Marimo Balls.

Cladophora ball "Aegagropila linnae"

A marimo ball is a rare growth form of algae, which grows into large green balls with a soft, velvety appearance.they are native to japan where they naturally grow at Lake Akan. They are also found in Iceland ,Estonia and scotland. They can grow patches on a lake floor at depths from 2 to 2.5 m. The round shape of the marimo is maintained by wave action that turns it.
In Japan the marimo has said to be a national treasure.
They where named by the Japanese botanist "Tatsuhiko Kawakami". Mari means bouncy ball and Mo is a term for plants that grow in water. So , marimo means bouncy plant.People often mistake them for living animals because they are usually moving around in the tank.

I first saw marimo balls when i was looking for an aquarium, then I immediately wanted them!

how to grow marimo balls

Your marimo friends will grow in tap water at room temperature as long as the water is changed every one or two weeks.
The growth rate of Marimo is about 5 mm per year.they grow particularly large, up to 20–30 cm (8–12 inches).

All they need is normal household lighting for them to make food, otherwise, indirect sunlight is fine.
You should turn them over once in a while for them to keep their round shape.
Marimo's are actually VERY easy to take care of, probably one of the easiest plants that live in water.
you just have to change the water once a week and your done!" make sure NOT to have age killer in the water!!!!"
1* They do not float unless the water is squeezed out of them.
2* They are NOT moss, they are a very unique type of ALGAE.


They need little light, they do best with lamp light especially if you have smaller, rolled marimo.
if so, they will start to grow outward like they do naturally and look very fuzzy.

Health problems:
If your marimo turns grey then simply flip it over and make sure the grey area gets light.
If that doesn't not work then you can get a bowl, add water, ice and salt, let them soak in that for about 3 hours .

they are a VERY easy plant ( ALGAE) to take care of and are nice for people that want a plant but don't have the time to take care of it.
They are also a helpfull addition to to fish tanks, thus they act like miniature filters cleaning out the water.

please ask any questions!


MaryA17 made it! (author)2017-08-24

My Marimo Balls are nice and healthy and I only use spring water or river water on them. The glass gets that cruddy, impossible to remove film along the the top rim where the water sits. Is there a different type of water, or additive, that is Marimo safe that I can use to keep the glass looking nice. I really is impossible to get off. Thanks!

Bln0 (author)2017-08-14

my moss balls turned a grayish color after I put them in my tank, what can I do to get them back to green?

Me123456789012345 (author)2017-05-31

Is it okay to to get marimo from pet smart? Are they fake or real and how do you tell? Thanks

Tystud (author)Me1234567890123452017-07-24

Not sure about Pet Smart, but Petco has some fake ones(the one where I live anyway).

Some signs it's not a marimo:

1. They are not specifically advertised as marimo balls. IE. If they are advertised as "moss balls", "betta buddies", "fluval", or some other thing.

2. If they are floating. These are sometimes anchored to rocks with string.

3. If they have string tied around them. This is to give them a round shape, which real marimo will have naturally.

Those are ones that I have seen anyway. Though they didn't have them advertised as marimo, they are designed to look quite similar to them. They where also in with marimo balls that weren't marked as being anything different.

Hope that helps a little.

OrCHIDLOVER (author)2016-07-15

Wow first off Thank you for taking the time to do this for beginers like myself . i read comments below and i would like to tell you dont let one bad seed discourage you. i agree not all meths are the same but not every metheod is fit for eveyone you might do it one way and it works for you and the rude person might use a different method the point is you took the effort to help wat did they do so keep helping and posting and again thank you for the helpful tips

i didn't see a rude comment...? If there was one I would hope that it was flagged or something, there is no reason to be mean. Anyway thanks for saying something☺

fishyfishy (author)2017-02-22

Just got mine in the mail all dry. Can i drop in aquarium and revive? They were dry for about 4-6 days.

murf0413 (author)2017-02-05

just received about a dozen marimo balls that I'm giving as gifts for valentines day. 6 are pretty big, 6 more coming that should be small and 1 heart shaped one for the hubby. can i leave them in the baggies that they came in until the 13th or 14th? today is the 5th. don't want to hurt them but need to know if i should just give them out early

neetz (author)murf04132017-02-05

Hi! Are the baggies filled with water?

murf0413 (author)neetz2017-02-05

no, they are not filled with water but there is moisture in the bag, you can see it

cuppbro0556 (author)2016-09-22

my moss ball is turning into a fuzzy ball is that good or bad?

NicoleM125 (author)2016-05-16

Can you place them with other aquatic plants? If so, what types?

they are fine with any other types of aquatic plants as long as they are fresh water. marimos do prefer colder water though so if you were to keep them with other plants in a heated tank, a night in the fridge every once in a while would do them good :)

Madzthecrazyone (author)2016-08-30

I was under the impression that the marimos do float on their own because when they photosynthesize, the bubbles cause them to float up

LisaG114 (author)2016-03-16

I have 4 large Marimo and 6 goldfish and 1 sucker fish in a 10 gallon tank, my ? is can I feed the moss in the fish tank with the fish? Yes I bought food for them, the company I bought the food from said yes, but I would like a second opinion. Also how often do I feed them?

HaoX3 (author)LisaG1142016-06-28

once you change the water for the marimo, you can feed them.

Madzthecrazyone (author)HaoX32016-08-30

I would even recommend 20g per fish when it comes to goldfish. Especially if they are common gold fish

ElizabethM4444 (author)LisaG1142016-06-09

Most "aquatic plant food" is okay to be used in a tank housing gold fish and sucker fish. I've only heard of it effecting things such as shrimp, who are sensitive to copper in fertilizers. The goldfish might eat the Marimo balls, like they do almost any plant you put in their tanks.

On a different note please get a bigger tank for those fish. Gold fish need a minimum of 10 gallons each due to their high waste levels and how big the get. Also if that sucker fish is an Chinese algae eater, if could become a big problem. Contrary to the name, Chinese algae eaters do not eat very much if any algae and will often prey on the slime coating of fish, such as goldfish, resulting in very nasty looking and painful woods on the fish they attack. This happens more commonly as the algae eater gets older and you'll often see them chasing the other fish around.

These are the things pet shops don't tell you.

Emmyisnotonfire (author)2016-08-30

um hey do you know general pricing on Marimo? I have wanted one for like 4 years now and im ready to get one, any and all help would be appreciated. Thanks!!

in chunw made it! (author)2016-01-14

Hi! I have brought 2 small marimo balls from Hokkaido 6 months ago.

I put them on the desk of my office and change water once in 1/2 weeks.

The attached are the photos and I am not sure if they are healthy as they don't look as deep green as the others. Is there anything I can do to help them? Thank you!

HaoX3 (author)in chunw2016-08-19

They looks really heathy and became fuzzy!! Congratulations!

LauraB139 (author)in chunw2016-04-15

I know that it's been a while since you posted, but these guys look beautiful and healthy! I'd give them some plant food designed for aquariums (you'll have to convert the amount to the size of the jar, or place the water and plant-growth solution in a clean (ONLY USE A PINCH OF AQUARIUM SALT with regular water) to clean out a recently discarded milk or juice jug--NO SOAP!!, a fill with a gallon of water and (usually) 0.5 ml of the plant mix in the jug and use this water when you do water changes.

in chunw (author)LauraB1392016-04-16

Thank you so much for your comments. So glad that they are healthy!
I have the "plant food" that they said is for marimo (bought with the marimo).
Yes, I will try to look for 2 clear bigger containers for them.
As it has been a while, I will take some photos of these two little guys and post it tomorrow.

12CatBat (author)2016-08-07

Hi, um I was cleaning my tank with my mom, and she accidentally removed the moss ball, it's been out of water overnight now and has completely lost its shape, it's more like a patch of moss clinging together can anyone help? I want my mossball back!

XxCrimsonxX (author)2016-07-09

I bought a small jar of moss ball 2 years ago from Japan in Hokkaido and forgot about it until recently ;-;
I changed the water as theres algae in it and realise its about the same shape as before.The moss is in dark green I'm wondering if its real or fake...i cant tell...

JJWWE2002 (author)2016-04-18

i have bought a moss ball and I don't know weather to put another one in so it has company what do I do.

amprest (author)JJWWE20022016-07-01

Marimo love company, so go for it! The more the merrier, just make sure they have room to grow and roll around in :)

JoannaEwe (author)2016-06-18

I have a Marimo ball I purchased a few years ago. It has been living in my turtle tank since I got it, and seemed happy until recently. There have been a few small "sprouts" in the tank on occasion, which I hoped would grow into a new little ball, but I think the turtle ate them! This week, it has begun to open up, so I took it out of the tank and put it in a small vase on my kitchen windowsill. It is a low light area. I turn the vase often, and my cats drink the water so it gets filled regularly. Will it regain its shape? I know it is bigger than when I bought it.... Will any small scraps become new Marimo balls?

HaoX3 (author)JoannaEwe2016-06-28

Ahaa, the ball shape of marimo is artificial from Japan because the natural cannot be sold now. The sprouts themselves can not grow to a ball. Also, it is better to keep the water cleaning and without turtles and fishes. Don squeeze the ball but gentle make it to a ball shape when you change the water. hope this will help you.

JoyR19 (author)2016-05-04

I just got my marimo, i had planned on putting it in an outdoor koi pond and wanted to know if that was a good idea.

DebbieR59 (author)2016-03-14

Some one told me when they look a little sad...put them in a cup of clean water and put it in the fridge overnight. Is this true?

DebbieR59 (author)2016-03-14

Some one told me when they look a little sad...put them in a cup of clean water and put it in the fridge overnight. Is this true?

instruct-a-cat (author)2016-01-21

Hi! My sister just got me 4 Marimos (3 big ones and 1 small one) for Christmas and I was wondering if anyone could answer my questions about them. When she gave them to me they were in a medium sized container in quite dirty water. I haven't had the chance to do anything with them yet, and I have a few questions about their habitat:

Will their stay in the unclean container affect their health later on?

Should I put them in separate containers or will that affect them?

Should I put any pebbles or coral into their jars or not?

How should I squeeze them when cleaning, very gently or quite powerfully?

Thank you so much! I'm so excited about my Marimo friends!

1. The dirty water can affect their health, change the water as soon as you can.

2. You can put pebbles in their container if you like but it is not needed.

3. Squeeze the marimo gently with low power,

I hope this helped!! good luck with your new marimo.

Thank you! Yes it helped:)

SteveJ48 (author)2015-12-04


I have a small Marimo ball, which appears healthy and is a nice deep shade of green. Normally it sits at the bottom of the jar, looking cute. I change its water every week, and have had no issues so far. Recently, though, I've noticed that it's started floating during the day, and appears to have small bubbles coming out from inside of it- is this normal? Should I be worried? :(

lauren_sparta (author)SteveJ482016-02-22

Looks like you have a very healthy marimo! Nothing to be worried about!

lauren_sparta (author)SteveJ482016-02-22

Looks like you have a very healthy marimo! Nothing to be worried about!

Rommi_Gorillaz (author)SteveJ482015-12-04

all plants go through photosynthesis and thats exactly what your marimo are doing. they do float occasionally, unlike what is said in the OP. Its normal for them to "dance" and produce bubbles. it just means your marimo are very healthy. you should be proud.

SteveJ48 (author)Rommi_Gorillaz2015-12-05

Thanks! I was just a bit worried because I hadn't noticed it before- I normally work during the day and I assume it stops 'dancing' before I get home in the evening. ;)

RogueThetan (author)2016-01-12

Just to be clear... will my marimo balls survive in on my office desk where the only light source is fluorescent bulbs (no natural light at all).

Thank you very much.

Put your finger in the water to see if it is too cold if so try placing them in some sunlight for a short amount of time.

JalenaC (author)2016-02-13

hi I am planning on buying a Marino so I've been doing some research and I've noticed a few people talking about feeding their moss ball and they talk about either fish or some pretty store moss ball food. I don't plan on having any other living things in my tank just Marimo's. Is this moss ball food something I should be looking in to?

lauren_sparta (author)JalenaC2016-02-22

This food helps your marimo grow, it is not needed but it can be used. It is up to the owner.

jodeii (author)2016-02-13

Help! I just received my marimo balls today and would like to add them to my (daughter's) beta tank. However, since I have also been treating the water for a small fin rot on the old beta and adding antibiotics over the last several weeks along with frequent water changes, I am concerned about the tolerance of marimo balls to these chemicals? So far, I've completed a course of tetracycline, but after a relapse am now using Api's Bettafix, an all natural product, 2% melaleuca (tea tree oil) ....

lauren_sparta (author)jodeii2016-02-22

I would wait until the fish is healthy to place the marimo in the tank. Marimo work great with betas!

XDSweetstuff (author)2016-01-30

can you help? I just got a marmio ball today, and I know nothing about them.

KatieV4 (author)2016-01-02

hi! I have three marimo balls and two of them appear to be budding. I know this is how they reproduce however im wondering if they need any help with it. Should i separate the balls from their buds or will they do it themselves?

NilsW (author)2015-12-28

Hi my small marimo ball , that I just bought isn't actually well shaped , can I do something to make him more ball shaped ? , and also bought it to put in the tank of my triops and would like to know if it is bad that he'll need to be put in demineralized water ? btw thank you for the very interesting page you wrote about marimo balls :)

Chloeswoo (author)2015-12-12


My small Marimo ball seems to crack. I tried rolling it back to round shape but now it seems to have white spot at the crack area. Is it sick? How do I save my marimo?

About This Instructable




Bio: I love to make things! I am constantly finding new things to make and do. I love geeky stuff like Sherlock and doctor who.
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