Last Updated on April 23, 2023 by Coral Realm

Java Fern is an incredibly popular freshwater aquarium plant, known and loved for its stunning looks and ease of care. Java Fern turning brown is a common issue, and we’ll address that in this guide. 

It is scientifically known as Microsorum pteropus, and is sold under this name. You may also find it called Leptochilus pteropus. The two names are interchangeable, though the former is more common in the aquarium trade.

Java Fern is a very adaptable plant; it can be kept with a huge range of tropical freshwater fish species, and can thrive in many different water conditions. This ease of growth and unfussy manner makes it ideal for beginners to the aquarium hobby.

This complete care guide will give you all the information you will need to successfully grow and prevent Java Fern turning brown and keep this beautiful fern in your fish tank. The following table gives a quick overview.

Java Fern General Information

Care LevelEasy
Temperature Range68°F – 82°F (20°C – 27.8°C)
pH6 – 7.5
PlacementBackground, Middle
LightingLow – Moderate
Growth RateSlow – Moderate
Maximum Size13.5 inches
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Java Fern General Information

The Java Fern, as you could probably guess, is named after the island of Java in Indonesia in South East Asia. However it is not only found on this island, it can be found naturally in Malaysia, Thailand, Northeast India, and even some parts of China.

It can be found along riverbanks and alongside streams and waterfalls. Often it will be attached to rocks but it can anchor itself to basically any surface. It will grow both fully submerged and partially submerged. As such it is readily found in tropical rainforests growing on the forest floor.

Java Fern is a member of the Polypodiaceae family. Both Microsorum and Leptochilus are genera found in this family, so it doesn’t matter hugely what Java Fern is called; it is all the same plant!

By far the most common species used in the aquarium trade is Microsorum pteropus. As we’ve said before it can also be sold as Leptochilus pteropus. Don’t worry though if you see either of these names used it is referring to the plant we are talking about here! 

As the Java Fern has been popular and used in the industry for a long time there have been numerous varieties bred. The most common varieties are the needle leaf, narrow leaf, trident, and windelov. 

This plant doesn’t have true roots; it has rhizomes which anchor the plant to a surface. These rhizomes do help with nutrient uptake but in the main they are just anchor points. As such the main nutrient uptake occurs through the leaves.

This fern is readily available in most aquarium stores, and quite cheaply at that! It can also be bought online. If you get to pick your plant ensure that you get one which has nice green leaves. Browned leaves are a sign of an unhealthy plant, and you want them to have as much of a head start as possible. 

Common reasons for why Java Fern turns brown

One common reason for Java Fern turning brown is poor water quality. Java Fern, like many other aquatic plants, is sensitive to changes in water chemistry. High levels of ammonia, nitrite, or nitrate can stress the plant and cause the leaves to turn brown. In addition, low levels of carbon dioxide or other essential nutrients can also cause the plant to suffer and turn brown.

Another common cause of Java Fern turning brown is low light levels. Java Fern prefers low to moderate light levels, and too much or too little light can cause the plant to brown. If the lighting in your aquarium is too strong or too weak, the plant may not be able to photosynthesize effectively, leading to browning of the leaves.

Additionally, Java Fern may turn brown if it is planted too deeply in the substrate or if the rhizome is buried. Java Fern does not have true roots, but instead has a rhizome that should be attached to a surface, such as driftwood or rocks. If the rhizome is buried in the substrate or the plant is planted too deeply, it can become stressed and the leaves may turn brown.

Finally, Java Fern may turn brown if it is suffering from a disease or pest infestation. If you notice brown spots or lesions on the leaves, it could be a sign of a bacterial or fungal infection. If you notice small insects or other pests on the plant, they could be causing damage and leading to browning of the leaves.

More complicated reasons for Java Fern Turning Brown:

Java Fern can turn brown due to a variety of factors, some of which are related to its natural growth habits and others that are influenced by the conditions in which it is grown. A tricky one to navigate when dealing with Java Fern turning brown is low light intensity. This plant is adapted to grow in shaded areas of its natural environment, and if it is exposed to bright light for too long, it can experience photoinhibition, a process in which the plant’s photosynthetic apparatus becomes damaged.

Another more tricky reason for Java Fern turning brown is iron deficiency. Iron is an essential nutrient that is required for the formation of chlorophyll, the pigment that gives plants their green color. If the plant is not getting enough iron, it will not be able to produce enough chlorophyll, and the leaves will turn brown. This is often seen in aquariums with low levels of iron, which can be remedied by adding a plant fertilizer that contains iron.

Another possible reason for is general nutrient deficiency. Like all plants, Java Fern requires a range of nutrients to grow and thrive. If the plant is not getting enough of these nutrients, its leaves may start to turn brown. This can be caused by a lack of nitrogen, phosphorus, or potassium, among other things. Adding a balanced plant fertilizer can help to address nutrient deficiencies and ensuring the plant has the best aquarium substrate.

Java Fern can also turn brown due to disease or infestation. Fungal infections and bacterial diseases can cause the plant to wilt and turn brown, as can infestations of pests such as snails and algae. Treating the plant with an appropriate fungicide or pesticide can help to combat these problems.

Can you prevent Java Fern turning brown?

Java fern can turn brown due to a variety of complex reasons, including the breakdown of chlorophyll, nutrient deficiencies, and environmental stressors. Chlorophyll is the green pigment found in plants that is essential for photosynthesis. As the plant ages or experiences stress, chlorophyll can break down, resulting in the loss of green color and a brown appearance. Nutrient deficiencies, particularly in iron and potassium, can also cause the fern to turn brown. Inadequate levels of these nutrients can hinder the plant’s ability to carry out photosynthesis and produce energy, leading to brown leaves. Environmental stressors, such as changes in light or temperature, can also cause brown leaves. High-intensity lighting or sudden temperature fluctuations can damage the plant’s cells and lead to brown discoloration. These reasons can often be interconnected, making it difficult to pinpoint a single cause for the browning of Java fern.

To prevent Java Fern from turning brown, it’s important to maintain good water quality, provide appropriate lighting, and ensure that the plant is properly attached to a surface and not buried in the substrate. Regular water changes, adequate filtration, and testing of water parameters can help prevent stress to the plant. In addition, providing the plant with appropriate nutrients, such as fertilizers, can help promote healthy growth and prevent browning. If you suspect a disease or pest infestation, it’s important to isolate the plant and treat it accordingly to prevent further damage.

Preventing Java Fern from turning brown involves maintaining proper water parameters, lighting, and nutrient levels. Here are some tips to prevent Java Fern from turning brown:

1. Proper lighting: Java Fern prefers low to medium muted lighting. High output LED lights can be too powerful, so be careful! Too strong lighting can cause problems such as browning and wilting. Subdued fluorescent lighting is good for the health of Java Fern, as are LED lights which have an output of 5000-7500K. If you have much stronger lighting, then having floating aquarium plants to block some of the light can be very useful.

2. Adequate nutrients: While Java Fern does not require a high nutrient load, it does require some nutrients. Regular fertilization can help provide the necessary nutrients. However, be careful not to over-fertilize, as this can lead to an excess of nutrients, which can also cause browning.

3. Proper water parameters: Java Fern prefers a pH range of 6-7.5 and a water hardness of 3-8 dGh. Keeping these parameters within the recommended range can help prevent browning.

4. Avoiding algae growth: Algae can outcompete Java Fern for nutrients and light, leading to browning. Regular water changes and proper filtration can help prevent algae growth.

Unfortunately, once Java Fern has turned brown, it is difficult to reverse the process. However, if the cause of the browning is identified and corrected, the plant may begin to recover over time. Additionally, removing any dead or dying leaves can help improve the overall health of the plant.

Java Fern Appearance

Java Fern is a very good looking plant which won’t look out of place in any aquascaped tank. However, it’s important to note that sometimes it can face issues.

This plant lacks true roots and instead has rhizomes which act mainly as an anchor. The leaves grow directly from the base of the plant; there is no central stem.

Rhizomes can attach to many different types of surface and are not meant to be buried or planted in the substrate. As such this fern is often attached to wood, rock, and many other aquarium decorations. The best way to attach the rhizomes to a surface is with fishing line or something similar. This won’t leak or degrade chemicals into the water. Sometimes, java fern turning brown can be due to improper attachment.

In total the adult plant can reach a maximum height of about 13.5 inches. If given enough room it will also reach around 8 inches across. This height means it can be used in large community freshwater tanks at the bottom or middle levels, while it can also have its use in smaller tanks as well.

The leaves themselves are the main feature of Java Fern. They are quite leathery in texture and are very strong and hardy. Depending on the variety of fern the leaves can be a wide range of shapes, from narrow and long to broad and shorter. Normally the leaves are a bright green, but some variation is expected and in general the higher the light intensity the darker the green. In case of java fern turning brown, the leaves may change color or start to rot.

Below we will run through the differences in the leaf shape of the most common varieties of Java Fern you can find:

Java Fern Needle Leaf: This is a small variety of Microsorum pteropus, growing to a height of about 6 inches. As the name suggests the leaves are very thin and needle-like.

Java Fern Narrow Leaf: This variety of Microsorum pteropus has leaves which are narrower than the regular plant. Although not as narrow as the needle leaf. The leaves grow more upright and vertical than normal, and grow to about 8 inches, while the total size of the plant is 12 inches. In some cases, java fern turning brown can affect the narrow leaves more severely.

Java Fern Trident: Quite a unique and rare variety, it is highly sought after due to the multipartite leaves. The trident name is for the common tripartite leaves. The leaves are feathery and have as many as 5 lobes. This variety is less susceptible to java fern turning brown due to its hardiness.

Java Fern Windelov: A beautiful variety of Microsorum pteropus, the Windelov has leaves which split and branch into three thin leaves at the ends. This gives a stunning bushy effect to the overall fern.

Java Fern Windelov

Java Fern Benefits

There are a multitude of benefits from keeping Java Fern in your planted fish tank. 

Firstly, like most plants, Java Fern helps to oxygenate the water. During photosynthesis carbon dioxide will be drawn from the water and the main byproduct, oxygen, will be dumped into the water. 

Fish “breathe” oxygen under the water through their gills, and release carbon dioxide as a byproduct. If there are no plants in the tank, without agitation from an aquarium wave maker for instance, then carbon dioxide can build up and the oxygen concentration will decrease. This can cause fish to become quite lethargic and sluggish. Not only is this not good for the fish themselves, but you will see them unmoving and rapid gill movements. 

Seeing fish this way can cause you worry, and will lower your enjoyment of your tank. 

Java Fern is also loved by shrimp for the algae that can grow in its leaves. It can also provide a great refuge for young fish and fry.  

Java Fern Care

Java Fern Care

Tank Requirements for Java Fern

Whilst Java Fern is very easy to care for and will grow and thrive in a range of conditions, like fish all aquatic aquarium plants have their ideal conditions. Obviously the closer you can recreate the natural conditions from where it is found in your tank then the better. 

South East Asia is the natural range of Java Fern, which includes Thailand, Malaysia, and parts of China and India. In these ecosystems this fern is often found growing near running water such as streams and rivers. It doesn’t always have to be submerged completely; it will happily grow on the floor of rainforests too. 

As these hot tropical conditions are the norm then the temperature should be between 68 and 82°F, or 20 and 27.8°C. 

Also as it is found in these conditions it doesn’t have a great need for an influx of carbon dioxide from an aquarium CO2 regulator. The carbon dioxide that is brought into the water via the agitation from an aquarium powerhead or wave maker, or filter output should be enough. Also along these lines it won’t need a high nutrient load. 

As Java Fern is naturally found on the jungle floor and stream edges, it doesn’t get, or like, high lighting. It prefers low to medium muted lighting which mimics the amount it will get through the canopy. High output LED lights can be too powerful, so be careful! Too strong lighting can cause problems such as browning and wilting, as we will discuss in the next section. 

Subdued fluorescent lighting is good for the health of Java Fern, as are LED lights which have an output of 5000-7500K, but it’s important to be mindful of java fern turning brown due to excessive lighting. If you have much stronger lighting, then having floating aquarium plants to block some of the light can be very useful.

As for tank size, this aquarium plant doesn’t grow massive by any standard, so can be used in small tanks of 10 gallons. It could be used in smaller nano tanks such as a 5 gallon tank, but it generally isn’t recommended due to the risk of java fern turning brown. In these very small nano tanks the plant will be closer to the light and maybe won’t have as much room to grow. This could cause the health of the plant to deteriorate.

The pH should be between 6 and 7.5, ideally under 7, to mimic the slightly acidic soil and water from the rainforests of its natural home. A water hardness of 3 to 8 dGh is recommended as well to best mimic these conditions. 

One of the great things about Java Fern is that it doesn’t have true roots, instead having rhizomes. This means that it shouldn’t be planted into substrate. Instead the rhizomes should be attached to rock, or driftwood. This means that it can be used in bare bottom tanks, and can also be used in the middle of the tank on any tank decorations you have. You can attach the rhizomes using wire. 

Java Fern Maintenance – Should you remove brown Java Fern Leaves? 

Java Fern Microsorum pteropus

Microsorum pteropus

If your Java Fern has only a few brown leaves, you can remove them. Brown leaves are usually a sign of old age or damage, and they will not recover. However, if your Java Fern has many brown leaves, you may want to consider the cause of the problem and address it instead of just removing the leaves. Removing too many leaves at once can cause additional stress to the plant, so it’s important to take a balanced approach. It’s also important to note that brown leaves may still provide some benefit to the plant by serving as a nutrient source or providing support for new growth.

Firstly, ensure that you don’t have the rhizomes buried in the substrate. Whilst this is a common thing it will cause the plant problems. Instead the rhizomes should be attached to something. The rhizomes need to be free to help with nutrient and water uptake. 

Don’t get frustrated if you don’t see an immediate growth spurt once you’ve added the plant to your tank setup. It can take a little while for the rhizomes to attach fully and for the plant to familiarize itself with your aquarium. Once this teething process is out of the way you will see growth. 

Another key aspect of maintaining the health of your plant is to keep the water parameters stable. If you have large fluctuations in the temperature, pH, or hardness then the fern will react badly. 

Whilst you may not need a huge amount of nutrients in the water, an aquarium liquid fertilizer can help the overall health of your Java Fern. Be careful though, as you don’t want to add too much and risk an algal outbreak. A little at a time is your best bet. You can always add more but can’t take it back if you add too much!

There is no need to add tablets or other solid fertilizers as the plant draws the vast majority of its nutrients directly from the water column through the leaves. 

Java Fern is sometimes prone to burn spots and Java Fern Melt. We will discuss this further in the common issues section, but you will want to prune off these leaves, as close as you can to the rhizome. 

You can let the fern grow as it wills in your tank. It will further it’s growth by extending its rhizomes and growing up from there, and will also produce little plantlets from its leaves. These will drop and produce new plants. 

These plantlets begin growing from small dark spots in the underside of the leaves once they are mature. Don’t worry if you see these dark spots! They aren’t a sign of disease, just an alternative method of propagation, which will be discussed further later in the article. 

However if you want to keep your plant looking more trimmed and neat then you can do this too. You can remove the plantlets as they grow, and you can also trim excess leaves if you wish. Trimming the rhizome if you can see it has extended too much is also an option. 

The only other major concern you need to keep in mind is that during cleanings and water changes, if you take the plant and it’s attachment out of the tank, it needs to be kept moist. Either you can place it in a bucket with tank water, or you can spray it with water from a misting bottle. If the plant dries out it will damage it greatly and you may find yourself having a battle to get it back to 100%.

How to Grow Java Fern

The key detail in how to successfully grow Java Fern in your aquarium is how you plant it. That is, it doesn’t have roots so can’t be planted in the substrate!

As we have said before, instead of roots this plant has rhizomes. Whilst their main function is to anchor them to a surface they also aid in nutrient and water uptake, and also in growth. If you plant them into substrate you will find the growth rate slows, if not stops, and after an extended period the plant’s health may deteriorate.

So what can you do instead? 

Well, that’s entirely up to you and your imagination. 

Attaching it to rocks and driftwood can create some stunning results, while it can also be attached to other decorations as well. 

Ideally you want to choose a rougher surface with plenty of room for the plant to spread and grow. A rough surface provides more anchoring opportunities for the plant and so it will grab on quicker than it will with a smooth surface. 

You can attach the rhizomes to your chosen item using fishing line or other wire. Ideally you want to use something that won’t rot or rust in your tank. Any rotting or rusting items can contaminate your tank. 

If you have a choice of wire color, then go for a darker color to match the color of the rhizomes. This will mean that you won’t be able to notice the wiring.

After a few weeks the plant should be fully attached and integrated onto the object you’ve chosen. If you wish you can remove the wire or whatever you’ve chosen to help anchor the rhizomes. If you can’t see it then you don’t need to as the rhizomes will cover it as the plant grows, but if it is obvious then you can carefully remove it.

Where you decide to place your Java Fern plant is entirely up to you and your individual tank setup. With a smaller tank it is advisable to place it at the base and nearer the back of the tank; this is to allow it to grow fully, as it can be quite large in small tanks. 

If however you have a large tank, you may find you want the plant to be higher up in the water column, such as attached to a large piece of driftwood. 

The beauty of having the plant anchored to a decoration means that if you aren’t happy with how it looks you can easily move it!

Java Fern Propagation

It isn’t difficult at all to propagate Java Fern. There aren’t any specific tank requirements or special care it needs. 

There are two ways in which you can propagate easily in your aquarium. We will run through both below. These are both methods of asexual reproduction. There are other methods available, and ways of sexual reproduction, but these will require a lot of hassle!

Perhaps the most basic and simple way is to carefully, and with a very sharp knife or scissors, cut the rhizome in half. Carefully pry one cut section away and disentangle the leaves if you need to. Then reattach the rhizomes of the free half of the plant to another object in the tank. Once everything has settled down then both plants will grow and spread as normal. 

The other option is to allow the plant to mature and naturally asexually reproduce via apomixis. Once the plant is old enough and established in your tank it will begin to develop dark black spots in the underside of the leaves. While it is easy to think the plant is getting diseased this is actually the start of something quite cool.

From these dark spots will grow small Java Fern plantlets. After about 3 weeks these plantlets will grow leaves and can be cut away from the mother plant using the sharpest scissors you can find. It’s always best to sterilize the scissors first, to ensure you don’t transfer anything malicious into the tank. 

Once these plantlets have been cut away you can attach them as is standard to another object in the tank. These plantlets will then start to grow as normal, and the process will start again! 

Compatibility of Java Fern – Suitable Tank Mates

Java Fern Tankmates

Otocinclus Catfish on Java Fern Leaf. Credit: AquaticMag (Flickr)

As has been stated previously in this Java Fern care article, it really isn’t a fussy plant. And added to that the leaves are fairly tough, which makes the plant unappealing for herbivorous fish. So as you would expect from a hardy plant like this it is suitable to be tank mates with a wide variety of fish. 

Not only is it perfect to be housed with smaller freshwater fish such as Guppies and Molly Fish, it can also be housed with more aggressive larger fish too. Fish such as Catfish and Cichlids which have a bit of a reputation should leave Java Fern alone. 

Whilst there is no absolute guarantee that large fish won’t eat it, there is evidence which says even large bottom-dwelling herbivorous fish like Plecos will leave Java Fern alone. 

You can give your new plant the best chance of thriving in a community tank by ensuring that it is fully and strongly attached to the chosen decoration with wire. During the first few weeks the rhizomes won’t have fully attached so it can get knocked off its perch, especially by larger more aggressive fish.

If you find that your fish are biting and eating your nice new Java Fern, then you can try adding more plants into the aquarium to give them other options. Hornwort is a great option; it can survive being hounded by herbivorous fish, and can also be floated to prevent excess light to your fern. 

Another thing you can do is add vegetables such as cabbage and lettuce to your tank. “Plant” these in the substrate, and your fish should find them a lot more palatable then the fern!

Common Issues With Java Fern (not just brown leaves)

Java Fern Common Issues

The most common issue with Java Fern is that it is planted wrong. It is very easy to mistake the rhizomes as roots and bury them in the substrate as per any normal rooted plant. However if you do this the plant will die eventually. Sometimes it can hang on a while, but it will kill it. So if you see your Microsorum pteropus turning brown ensure you have it attached to a rock, bit of driftwood, or other decoration.

Another common problem is Java Fern melt. This is a common issue and is characterized by large brown spots forming on the leaves, and can cause the whole plant to turn brown and go to mush, effectively “melting”.

Java Fern melt can be caused by dramatic fluctuations in water conditions. Check your aquarium heater and filter to ensure that the conditions are stable. You should also check the lighting in the tank. Having much too intense lighting can contribute to melt as well. If you cannot dim the lighting then think of getting some floating aquarium plants to help block the light to the fern. Having very low nutrient levels in the water column can also contribute to Java fern melt. Try adding some to increase nutrient load to give the plant a boost.

The first time we kept Java Fern in our tank we mistook the natural asexual reproduction process of apomixis with something sinister. Apomixis starts with small dark spots on the underside of the leaves, from which plantlets grow. But these can easily be mistaken for the start of disease or Java Fern melt. But don’t worry! This is a totally natural process. And melt has much larger brown spots, which you can’t miss. 

If you find dark spots which aren’t growing and developing it can signal signs of other troubles however. They could be burn marks, in which case you will need to turn down the light intensity, otherwise they could be signs of nutrient deficiency, in which case add some liquid fertilizer.

If you find you are having a problem with algae, you can perform regular water changes of 25%. Also ensure you clean the tank and filter properly, such as with a good aquarium vacuum cleaner. You can also try adding some algae eaters such as Plecos, shrimp, and snails. Also ensure that your filter media has been cleaned and changed, and that your filter is running as it should. 

Conclusion – Is Java Fern right for your Aquarium?

Java Fern is perfectly suited for the vast majority of freshwater aquariums. Not only are they simple and easy to care for but they are also suitable to be housed with larger herbivorous fish.

This makes them perfect for both beginners and experienced aquarists with large community tanks. 

There are numerous varieties that have been bred, so there are many versions of this stunning plant. From the Java Fern Trident to the Java Fern Windelov, you can be sure that your tank will look better for having it!

You may also like the following care guides:

Featured Image Credit: AquaticMag (Flickr)

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