Marimo Moss Ball Care Guide

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These crazy-cool little green balls of moss called Marimo Moss Balls are some of the more popular choices of live aquatic fauna you can use in designing your perfectly aquascaped betta fish aquarium. These incredibly beautiful, albeit naturally quite bizarre looking, Marimo moss balls just so happen to be incredibly easy to care for as they require practically no special attention in keeping them happy and healthy. If a moss ball can be considered happy that is… I like to think so.

First discovered way back in the 1820s, a Japanese botanist in all of his superior creative wisdom decided to name these funny looking green fur balls after a word for aquatic plant life mixed with a play on words for the word ball. Basically, Marimo means ball of seaweed or seaweed ball. Interestingly enough, Marimo moss balls are actually not moss at all. These so-called balls of moss are actually a quite rare form of spherical algae. To make things even stranger, they are relatively hollow inside. There is no hard kernel of mass inside holding all the algae in place.

Marimo moss balls take their time growing at a rate of about 5 mm per year.

Marimo moss balls take their time growing at a rate of about 5 mm per year. The freshwater lakes of Japan, Iceland, Scotland, Australia and Estonia are where these moss balls call home. In these freshwater reserves they have been documented to grow between eight and twelve inches across. That’s… actually quite impressive!

One of the almost magical qualities about the Marimo moss ball concerns the incredibly beautiful lore surrounding them. There is a legend that tells a story of two people wildly in love with each other that wanted for nothing more than to be with each other to the end of time. At one point their love was forbidden and the lovers fell into the water. As they fell into the water their hearts transformed into Marimo balls. It is said that a Marimo moss ball will bring whatever your heart desires to not only the receiver but the giver as well. This is why I buy my Marimo moss balls in bulk… 🙂

If properly taken care of, the Marimo moss ball can live to be well over 100 years old. That being said, I can imagine that I will have some very confused great great grandchildren once their inheritance reaches them. And, speaking as a fairly active betta fish enthusiast… I’m pretty sure Marimos will comprise my net worth and therefore passable inheritance. Because… my betta fish are pampered and that stuff gets expensive! But my fish are happy and that’s all that matters right?

Where Do Marimo Moss Balls Come From?
As I said before, Marimo moss balls really don’t have any special requirements when it comes to housing and maintaining them. There are couple tricks and things to consider though. Right off the bat, you really don’t want to keep your Marimo anywhere that receives direct sunlight. When you take into consideration the natural habitat of the Marimo moss ball, you start to understand that they like the really dark areas at the bottom of lakes and would really prefer not to go out suntanning is much as possible. Overexposure to direct sunlight is one of the only things you have to watch out for in maintaining a happy and healthy Marimo moss ball.

Marimo moss balls get along fine in tanks with other creatures living within. Almost all of my betta aquariums have at least one Marimo. If you have a community tank, Marimo’s are fine in that set up as well. Aquatic creatures of all types and sizes enjoy having Marimos in their tanks for several different reasons. My betta fish for example, they really like resting on top of it or hiding behind it. Sometimes I’ll find one of my fish gently rolling the Marimo across the bottom of the aquarium. It’s actually really entertaining to watch.

My betta fish for example, they really like resting on top of it or hiding behind it. Sometimes I’ll find one of my fish gently rolling the Marimo across the bottom of the aquarium.

One of the only types of aquatic creatures I’ve run into a problem with housing in the same tank as a Marimo ball is the overly curious pleco. Plecos like putting everything they can in their mouth. If you leave a pleco in an aquarium with a for Marimo long enough, it wouldn’t be unusual to find there are chunks missing from the poor little green fur ball. While not harmful to the pleco, I’m pretty sure the Marimo doesn’t enjoy it as much. There may be other fish and other creatures out there that enjoy trying out a Marimo salad for lunch, so it’s always advisable to watch the interaction of your Marimo’s tank mates closely for a while just to make sure there is no funny business going on. The worst thing that can happen in the event of Marimo ingestion is that you’ll just lose chunks of your Marimo. I do suppose if you have a very overambitious eater, constipation may be an issue… But honestly that’s overthinking it to a degree that I wouldn’t even really worry about.

Just as a side note, not relating at all to betta fish aquariums, Marimo’s can live in brackish water. There is a lake that Marimo’s are found in where the population and density of Marimos to be found actually rises within the parts of the lake with higher salinity. If you take a look on various aquatic plant websites, it’s not too hard to find posts explaining that people’s Marimos thrive in salinity up to the mid-end side of brackish conditions. All that to say, if you happen to have other fish aside from betta fish (and I’m not judging) Marimo’s are versatile and you may want to try throwing one in a brackish tank.

Learn To Love Changing Water
Regardless if you keep your Marimo moss ball in a bowl or vase all by itself (yes you can do that if you want to) or in an aquarium with a betta fish, you are most certainly going to want to perform water changes. Water changes are, in general, a pretty important thing when you’re keeping anything living inside of a body of water. Marimo’s are living organisms!

The water changes that you would normally perform in an aquarium with a betta fish in it are more than adequate for the Marimo as well. In a tank with only a Marimo in it… You might try to perform regular water changes once weekly. Especially when it’s hot outside because, you know, evaporation happens alongside rapid biological growth in warmer temperatures. You don’t want to dirty Marimo moss ball. In a jar or other container that is housing the Marimo by itself, tapwater for all intents and purposes should be fine.

Personally though, if you just so happen to have a water conditioner lying around I would go ahead and treat the water. Water conditioners are great not only for bettas but for all living organisms in an aquarium environment that are getting their water straight from the tap. Tapwater is known to have chlorine and heavy metals and other nasty stuff that living creatures don’t really like. And that is why I installed a reverse osmosis filter for my tap. Nasty stuff in the water I tell ya.

How To Clean Your Marimo Moss Ball
Marimo moss balls do get dirty from time to time. This is normal. A way to remedy a dirty Marimo situation is to clean a Marimo. Yep, you can actually clean a Marimo moss ball. Now, here’s the fun part about cleaning Marimo moss ball. What you want to do is pick up the Marimo out of the aquarium and place the Marimo in a separate clean container of water. And then the fun part. Squeeze! Gently though please. You want to squeeze the Marimo like a sponge, albeit gently because you don’t want to hurt it’s feelings, and release and squeeze and release and squeeze. You can also do this under a running stream of water. Marimo’s collect dirt, debris and algae (not just Marimo algae) not only on the outside service area but within the Marimo moss ball itself. Remember that a Marimo is mostly hollow on the inside.

If the Marimo accidentally breaks apart, it’s not the end of the world.

You can take the Marimo in between your two palms and gently roll around in your hands. While you’re doing this imagine that you are reshaping the Marimo into a perfect sphere. Marimo’s can break apart. So being gentle is pretty important. It’s kind of confusing I know. You have to both squeeze and roll and yet be gentle at the same time because they’re worried about breaking up. Yeah that’s definitely confusing. Once you have a Marimo in your hand and actually feel the resistance and the surface tension of the moss ball itself as you squeeze, you’ll have a much better idea of what you can get away with.

If the Marimo accidentally breaks apart, it’s not the end of the world. Marimo’s actually are highly resilient creatures (if you can call them creatures) and will mend themselves given enough time. While I have not done this myself, because I cannot get past the guilt associated with mutilation, I have heard of people breaking in half their Marimo’s on purpose and then reshaping them in between their palms into a ball thus creating to Marimo’s. Like I said, guilt associated, can do it. You have a Marimo moss ball living in a jar long enough, always sitting there listening to talk… you get attached.

One other thing to keep in mind is that Marimos in nature, as in in the wild, roll around on the lake floor with the current. When they’re sitting in your aquarium on your desk they don’t get a lot of that rolling around action. It’s not a bad idea to occasionally pick up your Marimo enrollment between your palms. A kind of Marimo moss ball massage I suppose. I’m sorry, my head still stuck on Marimo’s in the wild… Wild Marimo’s roaming the lake floor. I’m gonna have awesome dreams tonight!

Liking That Cool Water
if you remember the list of places I listed up above where Marimo is are found in the ”wild”, you’ll notice that those places are all cold climate habitats. The places I’m referring to in general are areas like northern Japan and Iceland. Therefore, it would stand to reason that Marimo moss balls like colder temperatures.

Now here is where you start thinking that there is a problem. Especially if you have betta fish. Because, as you know, betta fish not only enjoy warmer temperatures but actually and infactually need warmer temperatures. Between 78° and 80°F is the preferred betta fish aquarium temperature FYI. Marimo moss balls, for the most part enjoy temperatures no warmer than 75°. And even that’s a little bit on the warm and for the Marimo.

Now here’s the part that even I do not understand. All of my Marimo’s living in with their betta fish counterparts are completely fine. Natalie just fine, but thriving no less. I have had some Marimo’s for well over five years. All living in betta tanks their entire lifetime. These are warm water betta fish tanks with temperatures up to 82°. And most certainly no lower than 78°. I’m not sure if my Marimo’s are feeding off the power of love that I must be emanating towards them and that’s why they survive so well or… Maybe there’s something wrong with the information that I’ve been taught and am now passing on to you about the colder temperature thing.

What I’ve personally come to believe is that Marimo moss balls are a much more versatile aquatic plant life then many suppose that they are. While I am sure that a Marimo would rather be in colder temperature waters then the tropical waters of my betta fish tanks, it seems that my Marimo’s are still just fine. And as I said before, I’ve had some my Marimo’s for well over five years. And I haven’t been “cheating” with them and secretly replacing them in the middle of the night as they die.

One thing I do know for a fact is that my water parameters my betta tanks are kept as close to perfect as I possibly can get them 24 seven. I would therefore assume that Marimo’s can survive just fine in warmer temperature water as long as you make sure you keep up with your regular tank maintenance. Doing things like changing your water out like you should be for your betta fish.

Is My Marimo Sick?
Marimo’s can catch the flu! No, not really. But they can get sick. You can tell the Marimo moss ball is sick in the same way that you can tell that your betta fish is not feeling well. They turn a strange color. When living creatures start turning pale or gray or brown and they really shouldn’t be that color naturally, that’s a good indication that something is wrong with that living creature.

You can actually read and diagnose what is wrong with the Marimo depending on what color your Marimo moss ball is turning. The three sickly indicating colors of a Marimo are white, brown and black. If your Marimo is purple with gold speckles on it, check to see if your cat knocked over your nail polish in the aquarium. No but really, white brown and black are the colors that indicate a sick Marimo.

Why Is My Marimo Brown?
If you’re pretty green Marimo moss ball is turning an ugly brown color, you should attempt to gently clean the Marimo as outlined above in the cleaning section. One other thing that I must always do if I notice that my Marimo is turning an ugly brown color is remove him from the tank and place him (so what if I defined a gender for my Marimo moss ball!) in an entirely separate hospital tank. With nothing in it aside from the Marimo and clean water, this will surely aid in the Marimo’s recovery time and shorten the time your betta has to go without his Marimo friend

While in the hospital tank, you may notice that there are brown bits on what would be an otherwise solid green Marimo. These brown bits are often dead parts of the moss ball. If you want to try, you can attempt to carefully pick off the unsightly brown parts of the moss ball. If you do this you should add a little bit of salt to the Marimo’s hospital tank in an effort to encourage healthy growth and healing of the parts you picked out of Marimo moss ball.

One other thing to note is that if your Marimo moss ball doesn’t get moved around frequently enough, he might look fine at first glance, but if you roll him over you might notice that the bottom of the moss ball is that ugly brown color. Brown bottoms on moss balls can happen when the Marimo went for too long without receiving light on that area. While Marimo moss balls do not like direct sunlight, they are plants and they do need some light. So, just keep in mind that it’s a good idea to occasionally roll your Marimo from time to time. Also note that it does generally take a very long time of stagnation for a Marimo to develop a brown bottom. Very long time meaning periods of not moving for longer than several weeks. For the most part I’m sure this will end up being a non-issue for you.

Why Is My Marimo White?
if you look in your betta tank and find that your pretty green Marimo is now white… The Marimo is getting too much light. Oftentimes a slimy or otherwise unusual texture accompanies a white Marimo. First of all, if your Marimo is turning white make sure that you remove him from direct sunlight. If you do happen to notice that slimy textured I was talking about, generally what that means is that there is in invading species of algae that is using the Marimo surface area as a foundation to build little algae homes on top of. The invading algae is in essence choking the life out of the Marimo. It’s easy enough to deal with this algae chokehold on the Marimo by simply rinsing your Marimo often clean cold water. Sometimes you’ll notice that this foreign algae is grouped together in clumps rather than uniformly across the surface area of the moss ball. If the algae is in clumps together, you can easily remove the foreign algae with a pair of tweezers or even your fingertips.

Dealing with a white Marimo is actually not too big of an issue. As long as you make sure that the moss ball stays out of direct sunlight and is clean from any invading species of algae, your Marimo will be back to full health in no time.

Uh, My Marimo Looks Black…
the worst of the three colors that a Marimo can turn is black. If you notice that your Marimo has black spots on it, or is starting to turn black from the bottom up (or even the top down, it doesn’t matter) your Marimo is most likely decaying from the inside out. This can happen if the moss ball is been covered with an invading form of algae for too long. Just like that white algae condition I was talked about just above this. In fact, once you clean off your white Marimo, there’s a chance you might end up finding little black bits on your Marimo underneath all that white algae coloring.

If you do end up finding black spots on your Marimo, you have to literally cut them out. I generally use scissors, but you can use a knife or even try to pinch out the decaying parts with your fingers. Removing the black spots, the decaying areas, is the only course of action you have in giving your Marimo a chance to become whole and healthy once again. Once you’ve finished removing these little zombified bits of Marimo moss ball, you should take the Marimo in between your two palms and gently, very gently at this point, attempt to reroll and reshape the moss into a ball. As you can imagine, once you remove these bits and reshape the Marimo, don’t be surprised that your Marimo has shrunk.

Once you draw this nasty business of cutting apart your Marimo and reshaping him you should find that your Marimo is healthy and happy inside of about a month. Depending on how much decaying area was taken away the recovery time may be longer. If you were not able to successfully remove all the decaying bits, the decay actually can spread. So be vigilant in your quest for removing the black decaying pieces of Marimo. One last thing you might think about doing is to take the freshly operated on Marimo and place in a recovery tank until you have determined that he is all better. Placing your Marimo moss ball that is trying to recover in a community tank might not be the best way for it to recover. You would also want to place him in a tank that is colder rather than warmer during the recovery process. Try to do everything you can to match natural “in the wild” situations to encourage healing.

Gonna Buy Me A Merry Mo
~ Click Here To See Marimo Moss Balls On ~

While I hesitated even putting this part in here as it’s really not all that important in a “Marimo guide”, I did think it pertinent to at least touch on the subject. Marimo’s are not often found in all retail locations that sell aquatic pets. I know that in the area that I live in, if I don’t actually get to the store when they get the shipment of Marimo’s in, I’m out of luck for at least three weeks. Marimo moss ball availability seems to vary depending on where you’re located. But one thing I do know for certain is that they are always available online.

And that’s actually the part that I wanted to touch on. Don’t be afraid of buying aquatic plants online. I purchased plants for my betta fish aquariums on eBay and Amazon and even Craigslist a few times. 9.5 out of 10 times (probably a bit lower with Craigslist on there) the Marimo moss balls I receive from online retail outlets come in pristine health. The only reason I thought it pertinent to bring this up is that I remember the first time that I placed an order for an aquatic plant online and had major doubt the entire time I was waiting for the plant to get to my door. Then I started thinking about how these aquatic plants actually get to pet stores, like brick-and-mortar pet stores, and realized that it was no different than having it shipped straight to my door. In fact, I can’t see how it would be would be anything less than beneficial to the moss ball to cut out the middleman of the brick-and-mortar store and have the life aquatic plant delivered straight to me.

I’m not saying do not do your aquatic plant shopping at your local pet stores. I’m absolutely in love with my local mom-and-pop pet stores and have great working relationships with all of them. I highly encourage you to frequent your local mom-and-pop aqua shops if for no other reason than to build a good and long-lasting relationship with them. These people generally really know their stuff and they’re great friends to have if you have a question about something like “why is my Marimo moss ball turning purple with gold spots”. Yeah, that kind of thing.

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