In March of this year (2024 for all of you people of the future) I embarked on the not-so-epic adventure of purchasing Marimo balls. The are sometimes referred to as moss balls, or Marimo moss balls, despite the fact that they are not moss at all, and are actually a type of algae. To learn more about what Marimo balls are, and why people keep them, you can take a look at my previous post.
Quarantine? A Plant!?
In my last Marimo post I mentioned that I am currently in the process of quarantining my new Marimo balls. Unfortunately, starting around early 2021 imported moss balls sold throughout the US, and other countries, were found to be infested with zebra mussels. More on them in a minute. In the US, US Fish & Wildlife put out a statement that Marimo balls purchased anytime after February 2021 should be destroyed. Although they included a very brief section in their statement about quarantining Marimo balls, they high recommended that the “moss” balls instead be destroyed.
For quite awhile, due to importation bans, it was difficult, if not impossible, to find Marimo balls for sale legally within the US. Luckily for all you Marimo lovers out there, in recent years Marimo have become available to purchase again, typically through online vendors who cultivate their Marimo within the US rather than importing them. Cultivating Marimo in controlled conditions typically means that they can be grown without the risk of zebra mussel infestation.
However, in my opinion, Marimo balls should still be quarantined, especially if you’re planning on adding them to an aquarium or pond. So how, exactly, do you quarantine Marimo balls and what, exactly, are zebra mussels? Read on to find out!
Zebra Mussel 101
Who would think a tiny little mussel could cause such an uproar! DESTROY our adorable Marimo balls, over a little mussel!?
Unfortunately zebra mussels (Dreissena polymorpha) are highly invasive. They may look pretty innocuous, but zebra mussels are considered to be one of the most destructive invasive species in north America!
Small but mighty (but in a bad way), adult zebra mussels can attach to surfaces such as the sides of water delivery pipes. They can damage not only man made infrastructures, but also disrupt the natural ecosystem as well.
Zebra mussels, like other types of mussels, go through three stages of life. They start off as very small, microscopic in fact, larva before maturing into juveniles, and then adults. Because they are so small, especially in their larval stage, it’s easy to miss zebra mussels that may be hiding out in aquatic plants such as Marimo balls.
Typically, you won’t be aware that you have a zebra mussel infestation right away. Larval, and potentially juvenile, zebra mussels can hide out inside, or on the surface, of Marimo balls where they are not usually noticed until they become adults. Unfortunately, by the time you notice you have zebra mussels you may have already contributed to a big problem, introducing this highly invasive, destructive species into local waterways.
Be Careful About Where You Purchase Marimo Balls
Buying your Marimo balls from a responsible seller can ensure they are not grown or harvested in ways that would expose them to zebra mussels. Look for sellers within your country, who cultivate their own Marimo rather than importing them from unknown sources. Some sellers may even treat their Marimo balls with Potassium Chloride, a type of salt that can be used over a course of two weeks to kill zebra mussels.
I purchased my current Marimo from this seller on eBay. If I try out any other sellers in the future, and recommend them, I’ll add them to this post.
Even when you purchase your Marimo from a reputable seller, because of how insanely invasive zebra mussels can be, I feel that it’s still important to quarantine your Marimo balls. This is important even if you’re keeping your Marimo in their own jar, but especially so if you’re planning on adding them to an aquarium or pond. Zebra mussels have the potential to quickly outcompete other inhabitants of your aquarium or pond. They can attach themselves inside filters and other equipment, destroying them in the process.
How to Quarantine Marimo Balls
- The best way to quarantine Marimo balls is to keep them in their own, bare bottom, jar. I know I know, I want to add pretty rocks and cute decorations to my Marimo ball jar too! But that can come later, after the quarantine process. Keeping Marimo balls in their own jar will ensure you can keep a close eye on them and, worst case, that you don’t accidently contaminate your decor or other plants, etc.
- Do not let anything that comes in contact with your Marimo during their quarantine come into contact with any water sources. This includes outdoor bodies of water. It’s also important not to dump water your Marimo balls have been in down your sink! Do not wash their jar in your sink! If there are zebra mussel larva in the water or stuck to the sides of your jar, you can wash them down the sink into your septic tank or sewer system. This is exactly what we are trying to avoid!
- Once a week or so, inspect the jar your Marimo are in for signs of zebra mussels or other unwelcome guests. If you find zebra mussels, you can either destroy your Marimo using the US Fish & Wildlife recommended methods, or else treat them with Potassium Chloride for at least two weeks to kill the mussels. Remember, anything that has come into contact with contaminated Marimo balls may also have microscopic zebra mussel larva contamination, including the water your Marimo balls were in. Be very careful about how you clean or dispose of these items!
- If you need to change your Marimo balls’ water during quarantine, sterilize it before disposing of it. While they are being quarantined, when I change my Marimo balls’ water I boil their old water before dumping it down my sink. To be extra safe, I bring the water to a rolling boil for at least 2 full minutes before allowing it to cool and dumping it down my sink.
- Alternatively, you can use bleach to sterilize the water or any decor before dumping water. Use 1/3 cup of chlorine bleach per gallon of water and allow this mixture to sit for at least 10 minutes.
- Undiluted white vinegar can also eliminate zebra mussels. It can be used to clean any decor or your Marimo balls’ jar, but items must sit in undiluted white vinegar for at least 20 minutes.
- Do not expose your living Marimo to vinegar, boiling water, or bleach unless you are also trying to kill the Marimo ball! Use these methods to decontaminate any decor, the jar your Marimo are kept in, and old water before disposing of it.
- Tip: Keep your Marimo in a large jar, if you can, during quarantine. I decided to keep my small Marimo in a large jar. I don’t change their water very often, to be honest. I’ll likely do it more often once their quarantine time is over, but feel that they’d do fine in their large jar without water changes for at least a few months. Less water changes means you have to worry less about going through the process of sterilizing the water before you dispose of it.
- Some people say that your Marimo balls’ old water can be dumped outside, away from any waterways, or used to water plants, since zebra mussels can’t live long outside of water. I personally don’t do this during quarantine, mostly because it’s pretty easy just to boil the old water and know for sure that you would have eliminated any present zebra mussels.
- Marimo Balls should be quarantined for a total of 6 months! After 6 months, if you have not seen any signs of zebra mussels, you can officially declare your green round friends zebra mussel free!
My Marimo Ball Quarantine Adventures
My Marimo got to me on March 25th. To make it easy, following the 6 month rule, I’m going to officially call their quarantine complete in October. So, as of the time I’m writing this, they’ve been in quarantine for just around 2 months now.
Knock on wood, no signs of zebra mussels so far. Not that I was super worried, since the seller I purchased from came pretty highly recommended. After a few weeks I started to notice what looked like grains of sand on the bottom of my Marimo jar. Then a few weeks ago I had a bit of a scare when I noticed a very tiny shelled creature in with my Marimo balls. It actually turned out to be a baby snail! It just goes to show you how creatures like snails and mussels can sneak in on aquatic plants. I’m betting that one of my Marimo balls had snail eggs laid on them that I didn’t notice until the snails hatched and grew a bit.
So far I’ve found only 2 snails total. I took my time trying to decide what to do with them, and they sadly passed away before I could decide. I don’t think the conditions in the Marimo jar were ideal for them, maybe they didn’t have enough food? I was thinking about moving them into my shrimp/ramshorn snail tank but they were still too small for me to tell what kind of snails they were so I was hesitant to move them until I knew for sure.
I’ll either update this post, or else maybe just make a new one, when my Marimo balls’ 6 month quarantine is over. I’m really not expecting any issues, but it’s better to be safe than sorry. Especially when it comes to such an invasive species!
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