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Java Moss Keeps Dying – Best Solutions

Author: Nicole Malczan

Java moss is a Southeast Asian moss species that latches onto driftwood, roots, and rocks, typically in freshwater aquariums. You like the look of Java moss better than plastic grass, but the problem is your Java moss keeps dying. What should you do to prevent this?

Here are some solutions to stop premature Java moss death:

In this article, we’ll talk about the conditions of Java moss and how to tell if your moss is really dead or just needs some TLC. We’ll also elaborate on the suggestions above so you can start caring better for your Java moss.

Let’s begin!

Is My Java Moss Really Dead?

Java moss, as a moss species, is a plant. Like many plants, it can begin degrading in quality, turning brown and looking wilted and sad. This doesn’t necessarily mean the moss is dead yet though.

We recommend taking it out of the tank, giving it some nutrients and a bit of care, and seeing if it bounces back. Many aquarium owners have done just that and said that, for the most part, their Java moss has turned green and healthy again.

It’s also important to note that Java moss can become stressed from changes, such as being moved to your aquarium for the first time. If your Java moss is new and it’s turning brown, wait before you throw it away. The plant likely needs a few days to adjust to the changes you’ve induced. Once it’s more acclimated to its environment, the Java moss should be fine.

Some Java moss might get stressed like this each time they’re moved, such as when you go to change your aquarium water and clean the tank. Remember to have some patience with your Java moss.

How to Prevent Java Moss from Dying

Don’t Put Java Moss in Saltwater

If you recall our brief introduction to the Java moss at the start of this article, we mentioned how it grows most often in freshwater environments. That’s no coincidence. Freshwater is the most preferable condition if you want to keep your Java moss alive.

Although you might not think it, especially if your moss dies on you all the time, Java moss is surprisingly hardy. Even in slightly brackish water, it should be okay. Brackish water is saltier than freshwater, but it’s not the same as saltwater.

Growing the Java moss in purely salty water is not conducive to its survival. This poster on claimed they accidentally dropped the moss in their saltwater tank and the Java moss grew extensions. That indicated to the poster that the moss was okay in the saltwater, at least for the moment.

Most of the other posters were dubious, and rightfully so. It’s not everyday you see Java moss in a saltwater environment, because it’s not exactly well-suited for such salty conditions. If you want to keep your Java moss alive, make sure your water is only slightly brackish if it must have salt.

Feed Your Java Moss Nutrients Now and Again

All plants need nutrients to promote their survival, and the Java moss is no exception. Although its care may be relatively easy in other areas, by skipping out on key nutrients, your moss will die sooner than later.

What kind of nutrients should you give the Java moss? It needs the standard plant nutrients phosphorus, potassium, and nitrogen. You probably don’t have to offer it as much nitrogen as the other two nutrients considering the Java moss will happily feed on the nitrate found in fish waste (gross but true). Nitrate is a source of nitrogen.

To supply the Java moss with its other required nutrients, you can use an aquarium-friendly fertilizer like Seachem Flourish Freshwater Plant or API Leaf Zone Plant Treatment. Make sure you pass on the root tabs, as Java moss is a type of root feeder plant and thus these tabs will be ineffective.

Keep the Tank Temperature at a Range the Java Moss Likes

What kind of temperature do you set your aquarium? That depends on the species of fish in there, of course. Most fish prefer a temperature of 75 to 80 degrees Fahrenheit. Java moss likes water that’s slightly cooler, between 70 and 75 degrees. That said, you should always adjust your temperature to what your fish need, not your moss.

After all, Java moss won’t die in slightly warmer temps up to 80 and 90 degrees, they just do their best growing in water that’s no warmer than 75 degrees. That said, it’ll be rare that your aquarium temperature is set to that high a temperature, as most fish would scorch in 90-degree water.

Choose Your Fish Carefully

Speaking of the fish in your tank, you’ll want to make sure you don’t have a marbled crayfish in there if you care about the survival of your Java moss. This crayfish will gladly munch on all your Java moss.

The marbled crayfish, also referred to as the Marmorkrebs, came to modern fish tanks from Germany. As a parthenogenetic species of crayfish, the marbled crayfish reproduces asexually. Since it doesn’t need a second crayfish for reproduction, the marbled crayfish can grow its population at alarming rates. This issue is significant enough that many parts of the world label the crayfish as an invasive species. It can be a problem in aquariums as well for that reason.

Outside of the marbled crayfish, cherry shrimp will also feast on Java moss. The cherry shrimp or Neocaridina davidi has a brownish or reddish hue that makes it look like a cherry. When not snacking on Java moss, cherry shrimp may also use the moss for hiding.

Even your standard pet store goldfish will eat the Java moss, taking small bites that add up over time into one barely-there plant. We’d advise you to reconsider adding these fish species to your aquarium if you want your Java moss to live.

Does Strong Lighting Kill Java Moss?

You’re a bit surprised not to see any mention of lighting conditions that could kill the Java moss. Actually, in this area, the Java moss isn’t too picky. If you provide it a lot of light, it will live, and the same is true if the lighting in your tank isn’t as excellent (although you might want to look into why that is).

Do keep in mind that depending on how much light you can offer your Java moss, it will grow in different ways. For example, if your aquarium is a lower-light environment, then your Java moss will look long and thin. It may also take on a darker green hue than what you’re used to.

In brighter light, the moss becomes wide, dense, and thick. Too much light might encourage algae to grow with the Java moss, so don’t flood your aquarium with excess light either.

Can Java Moss Take Over Your Tank?

In some instances, you could have the opposite problem in your tank. Your Java moss isn’t dying, but rather, thriving, and almost to an extreme degree. Is this a good thing or a bad thing?

Having too much Java moss spread across your tank is definitely detrimental. You should keep an eye on the moss when you add it to your tank, as if it finds a place it likes, it can grow huge with new extensions that leave little space for anything else in the aquarium.

To control growth, get into a regular pruning habit, maybe trimming back your Java moss each time you change the water in your tank. Otherwise, the moss will get denser and denser, limiting visibility in the tank and preventing water from flowing throughout. This hurts your fish and Java moss too, as it will soon turn brown.


Java moss is a moss species that is common in freshwater tanks. If your moss dies often, you’re far from alone, as many fish owners find they have the same issue. We recommend fertilizing your Java moss, checking your water temperature, preventing your water from getting too brackish, and separating goldfish, cherry shrimp, and marbled crayfish from the moss.

With the information in this article, you can finally grow some Java moss that lives for a while. Best of luck!