Why Your Marimo Moss Ball Is Changing Color & 8 Quick Fixes!

Last Updated on 2024-07-02

The distinctive size and shape of the Marimo is just one of the reasons for its mainstream popularity; its long lifespan and ease of maintenance also contribute greatly to its status as a beloved pet. They look pretty, both in aquariums and in vases on their own. Marimo will rise, fall, and roll around in the container it is in. Despite the fact that the Marimo’s motions are merely a reaction to the light levels in the room, many owners treat them like a pet, only with less maintenance.

The health of Marimo can deteriorate, just like that of any other plant or animal, and on rare occasions, proper care may be necessary. Marimo’s health problems are usually simple and easy to treat, which is a good thing. Read on to find out how to properly care for moss balls.

Is It Normal For Marimo Moss Balls To Change Colors?

Marimo Moss Balls are adorable green growths that look like balls. Though they are commonly referred to as “moss balls,” these organisms are actually balls of algae that spend their entire long lives at the bottom of northern hemisphere lakes and rivers. Marimo balls are resilient and can tolerate a wide range of temperatures and water conditions, but they may take on an unusual color in extreme environments. They can change colors to brown, black, or white. This is a red flag indicating something is wrong. Color change is the most common concern with Marimo Moss Balls.

Why Is My Marimo Moss Ball Changing Colors?

Marimo balls in good health are bright green and have a smooth texture. Color changes may indicate that the water is overly hot, dirty, or poorly lit. If the color of your Marimo’s moss ball changes, it means that the Marimo is sick, and something has to be done to revive it.

Brown Splotches

One of the first steps in treating this is giving the affected Marimo a gentle cleaning. If washing the tank doesn’t work, try scraping off the spots to see if it helps, and then add some salt to the Marimo’s water to encourage new growth. It’s possible that your Marimo isn’t getting enough light on its underside if the brown patches are concentrated there. Every few days, you should move the Marimo so that all of its surfaces are exposed to sunlight.

Fading to White

It is a solid sign that a Marimo has been dying because of an excessive amount of exposure to light. It is possible to halt the process of deterioration by moving it to a location that receives more darkness and shade.

Turning Black and Starting to Fall Apart

These symptoms indicate that a Marimo ball’s internal health has started to deteriorate. To solve this issue, you should roll the Marimo back into its original form after eliminating all of the visible black areas. Even though this will make your Marimo smaller, once the dead parts are cut off, it will usually start to grow again.

Spots of White Slime

These are harmful forms of algae that prey on Marimo moss balls. To remove white spots from your Marimo, you can either place it in a container of clean water and wash it or use tweezers to remove the spots.

japanese marimo mossball green algae in glass of water

Why Is My Marimo Moss Ball Turning Brown?

Without proper maintenance, Marimo Moss Balls will turn from their original green to a whole new shade of Brown. If your Marimo moss balls have turned a uniform brown color, they are dirty and need to be cleaned immediately. Make sure you clean it the right way by following these instructions.

  1. After removing the Marimo moss balls from the tank, give it a thorough cleaning with dechlorinated tap water or aquarium water purchased in a bottle.
  2. If the first method of cleaning does not work and your Marimos are still brown, try submerging these Moss Balls in water and gently squeezing and squishing them in a manner that will not harm them.
  3. After attempting the first two ways, if your Moss Balls have not yet returned to their natural green color, you can place them in a jar with a little bit of aquarium salt and let them revert back to their original color.
  4. If your Marimo is still brown after that, or if it only turns brown on one side, that indicates that it isn’t getting enough light. Remove any obstructions that prevent the Marimo from receiving adequate light from all directions, and consider relocating the plant if necessary. If not, you might want to consider upgrading the aquarium light to increase the illumination in your tank.

You only need to give it some time with the new arrangement, and it will start growing again.

Why Does My Marimo Moss Ball Have White Spots?

When white spots appear, it could be because of either overexposure to light or an attack by algae that is harmful to the species.

  1. If there are white patches at the tips of green “hairs” that look bleached off, it indicates too much lighting. In short, your Marimo has been slightly scorched.
  2. You must relocate them.
  3. Use some clean, sharp scissors (we recommend cosmetic scissors) to carefully snip off the burned filament, then clean the area.
  4. If the white spots are firm and linked to the ball itself, then you’re dealing with aggressive algae.
  5. You will need to remove it with scissors or tweezers
  6. Give your Marimo a saltwater bath.
  7. Before adding Marimo back to their tank, make sure to clean the tank or container well with a drop of bleach and hot water. Rinse well, and fill with a clean tap, spring, or rainwater.

Why Is My Moss Ball Turning Gray?

You should not worry if the moss balls become a dull shade of brown or gray. They usually need cleaning when they turn from brown to gray. Give your Marimo a nice shower, and it should be fine. Use the instructions below to clean your moss ball.

Here’s how to wash your Marimo moss balls:

  1. Take them out of the tank immediately.
  2. Fill a container with fresh water and put them in there. Do not use normal tap water; instead, use water that has been treated.
  3. You should take care to handle them carefully and whisk them around in the water only a few times. Gently squeezing it like a sponge can help you get rid of any muddy water within. Repeat this process until the grass is lush, verdant green again.
  4. Rolling them between your palms and putting them away in a cool area will help them maintain their spherical shape.
  5. Make sure the moss balls’ container has been thoroughly scrubbed and refilled with fresh, treated water before reintroducing them.

Why Is My Moss Ball Turning White?

Marimo moss balls turn brown on one side when they aren’t getting enough light, and they turn white when they get too much. So, you should be careful about how much sunlight you give your Moss Balls.

  • If your tank is in a really sunny spot. Heat will build up in your moss ball container or tank if it is exposed to direct sunlight or too much light. To maintain the ideal water temperature for your Marimo Moss Balls, avoid placing the tank in direct sunlight.
  • If the light from your aquarium is too harsh for the moss balls, you may either reduce the intensity of the light or switch to a bulb that emits less light. When such an option is out of the question, you should find a new home for your Marimo.

Too much exposure to light might potentially be harmful to your Marimo moss balls, so getting this addressed as soon as possible is a top priority.

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Why Is My Moss Ball Turning Yellow?

If you’ve been keeping an eye on your marimo moss ball and noticed that it’s started to turn yellow, don’t panic! There are a few possible explanations for this change in color.

  1. It could be simply due to a change in the lighting conditions where the moss ball is being kept. Marimo loves fresh, natural light, but too much direct sunlight can cause them to fade. If you think this might be the case, try moving your marimo to a spot with indirect light and see if the color returns to normal.
  2. Another possibility is that the water in which the moss ball is being kept is too hot or too cold. Marimo prefers cool, clean water at around room temperature. If the water is too hot or too cold, it can cause the moss ball to turn yellow.
  3. Finally, it’s also possible that the moss ball is getting too much or too little nutrition. Marimo needs very little food, but if they are not getting any at all, they will start to fade. On the other hand, if they are being overfed, this can also lead to yellowing. If you suspect that this is the problem, try cutting back on fertilization and see if the color improves. With a little patience and care, you should be able to get your marimo moss ball looking green and healthy again in no time!

Why Does My Moss Ball Have A Brown Spot?

The Marimo moss balls may not become completely brown at all times. Sometimes you may notice that only one side of your moss ball is changing color. Most likely, this will show up on the underside of your Marimo moss balls.

  • Insufficient light can cause only one side of your Marimo Moss Balls to turn color. To solve this problem, simply flip them so that the Moss Ball’s entire surface is exposed to light.
  • Having a tank or holding unit that is far from a window. Make sure the Marimo Moss Balls have adequate lighting, either from an aquarium light or natural light. It is possible to restore the Marimo Moss Balls’ original green coloration by keeping them in bright indirect light.

Why Is My Marimo Moss Ball Turning Dark Green?

If you’ve noticed your marimo moss ball turning dark green, there’s no need to worry – it’s not sick, and it’s not dying. In fact, this change in color is perfectly normal, and there’s a simple explanation for it. 

Here are reasons why your marimo moss ball might turn dark green:

  1. Temperature. Marimo moss balls are native to cool freshwater lakes in northern Europe and Asia. In their natural habitat, the water temperature is fairly consistent all year round – between 50 and 59 degrees Fahrenheit. But when marimo moss balls are kept in captivity (like a fish tank), the water temperature can fluctuate quite a bit. And when the water temperature gets too warm, the marimo will start to turn dark green.
  2. Light. Marimo moss balls can survive without a lot of light, and in fact, environments with little light are ideal for their growth. However, if they are subjected to an excessive amount of light, they will develop a bluish-green color.
  3. Nutrients. Marimo moss balls have a very high capacity for removing nutrients from the water that surrounds them. However, if they are kept in a tank with water that is high in nutrients (like the water found in most aquariums), they may begin to take on a dark green color.
  4. Hormones. In their natural habitat, marimo moss balls are constantly surrounded by other marimo moss balls. But in captivity, they’re often the only marimo in the tank. And without the presence of other marimos, they can start to produce extra hormones, which can cause them to turn dark green.
  5. Stress. Marimo moss balls are very sensitive to changes in their environment. So if they’re moved to a new tank, or if the water quality in their tank changes, it can cause them to turn dark green.
  6. Age. Marimo moss balls might start to take on a more emerald or forest-green color as they age. There is absolutely no cause for alarm because this is completely normal.

If your marimo moss ball is turning dark green, there’s no need to panic. In most cases, it’s perfectly normal and can be easily fixed. Just make sure that your marimo moss ball is getting enough light, nutrients, and warmth, and it will soon return to its bright green color.

How To Keep Your Marimo Moss Ball Healthy

We find it very rewarding to take care of a Marimo moss ball since we learn so much from seeing it grow and change. We love how their bright, green style makes any sacred space feel more alive. We’ve figured out some great techniques for ensuring their continued health and prosperity throughout the years.

Here are the best practices for maintaining a healthy Marimo moss ball, whether you’re thinking about buying one or already have one.

Expose Marimo Moss Balls to Indirect Sunlight at a Medium-To-Low Intensity

Most likely, these moss balls were grown in a dark, deep environment. For optimal growth, you must create the same artificial lighting conditions they are accustomed to. However, you shouldn’t subject them to full sunlight. As a result, they will turn white and be stunted in their development. It’s like getting a bad sunburn when you forgot to use sunscreen: it hurts, and it’s not fun.

Since they are still kinds of algae, they require light to photosynthesize; therefore, occasional exposure to sunlight is good. But try to use indirect, soft light. A room with curtains drawn over the windows would be perfect. LED grow lights can be used to supplement the light your moss ball receives if your home does not have a window.

You Should Only Use Treated Tap Water for Your Marimo Moss Balls

Eutrophication, caused by an abundance of nutrients in the water, is a major factor in the decline of populations of Marimo moss balls, which are cultivated naturally in open water. Even though this is quite uncommon to occur at home, it’s better to be safe than sorry. As a result, nutrient-poor water, such as distilled or filtered water, is ideal for maintaining your moss balls.

Moss balls can flourish with very little in the way of added fertilizer or nutrients. Algae are resilient and will continue to expand their territory, provided the conditions are favorable.

Put the Marimo Moss Balls in a System Jar With an Open Top

Marimo moss balls, like all plants, thrive best in the open air. In a sealed container, the moss balls will die if their air supply is depleted. Don’t keep it inside a box because you think it’ll make a nice impression. Eventually, this will cause the moss balls to turn brown.

Your Marimo moss balls are best kept in an open system container such as an aquarium, fishbowl, or simply a glass of water.

Do Your Best to Maintain a Cold 17–23 Degrees Celsius in the Water and the Surrounding Area

The colder the water, the better for Marimo moss balls. If you reside in a warmer region, this could pose an issue. Your Marimo moss balls won’t make it through the summer months when temperatures reach the point where you want to peel your own skin off.

If you don’t want your Marimo moss balls to become brown and die from the relentless heat, you should keep them away from temperatures above 25 °C.

Marimo Moss Balls Should Not Be Mixed With Fish or Invertebrates That Will Harm Them

Some fish and invertebrates will eat Marimo moss balls since they are essentially balls of algae. If they weren’t looking for food, rough play with that could hurt them. You shouldn’t put goldfish, crayfish, species of Axolotls, ghost shrimps, and turtles.

If you’re set on combining your Marimo moss balls with other marine life, betta fish are the way to go. They won’t eat the moss balls, but they will play with them and even sleep on them occasionally with no negative effects.

The Marimo Moss Balls Should Be Washed Every Other Week in a Separate Container With Clean Water

Take it as a vitamin supplement for your Marimo moss balls. Plus, this keeps them bright green and lively, especially if they are starting to look a little dull or brown.

It’s possible that you’ll need to clean the moss balls more frequently if you keep them in a tank with fish and invertebrates because they are likely to have more dirt because they live with other inhabitants.

Every Other Day, Move Your Marimo Moss Balls in Their Tank by Gently Stirring the Water

In open water, wild Marimo moss balls are tossed and turned by the currents. This allows them to keep their round form without deforming. Unless you have other live creatures in the same enclosure as your moss ball, it will likely just sit in its container. It’s best to give them a slight swirl if they’re in a glass or container by themselves.

To Prevent Your Marimo Moss Balls From Sinking, Squeeze Them When They Float to Release the Trapped Air

The fact that your Marimo moss balls are floating is completely normal. All this photosynthesis has left them with trapped air. To put it another way, they need to release some gas by farting. Squeezing them gently is typically all that’s needed. There is nothing particularly wrong with this phenomenon. In some ways, it’s a sign that your Marimo moss balls are doing really well under your care.


So, is it normal for marimo moss balls to change color? In short, yes. While there are a few things that could be causing the discoloration – from too much light to poor water quality – most of the time, it’s nothing to worry about. Just keep an eye on your moss ball and make sure to adjust its environment if you think something might be off. And if you do happen to notice any other changes in your marimo beyond just color, be sure to consult an expert or take a picture and send it our way so we can help determine what might be going on.

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