9 Reasons to use Catappa or Indian Almond Leaves for Betta Fish

Indian Almond Leaves Catappa Leaves for betta fish
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Indian almond leaves, also known as catappa leaves, are one of the most popular leaves in the aquarium trade and arguable one of the most bought items by most fish keepers.

They are beneficial to soft water fishes and those that require low pH levels – which is most species of freshwater fish in the world.

And most importantly, it’s an important weapon to have if you’re keeping bettas as it prevents diseases, treats them, encourages breeding in betta fish, and provides food for baby fish.

In this post, I’ll share all you need to know about Indian almond leaves and how to use them, and some alternatives.

Keep on reading.

What are Indian almond leaves or Catappa leaves?

Terminalia catappa L. is a tree which spreads from Africa and upper Australia to the whole of Southeast Asia and can grow over 115 ft tall.

Although commonly referred to as Indian almond leaves, Terminalia catappa is the scientific name for these trees, and their leaves are called catappa leaves – or Indian almond leaves. Because the fruits taste like almonds, they are commonly called Indian almond leaves.

Indian almond tree

In Southeast Asia, locals call the Indian almond tree the ketapang tree its leaves the ketapang leaves.

Depending on their size, leaves can grow anywhere between 12cm (5 inches) to 38cm (15 inches) long.

9 reasons why Indian almond leaves are used in aquariums

There are many reasons Indian almond leaves are used in aquariums, but I’ll share the 8 main reasons why most hobbyists use them.

1. Indian almond leaves help reduce the pH of your tanks

Indian almond leaves help reduce the pH levels of your tank, and it’s probably one of the biggest reasons why many aquarists use them.

Everything natural you add to your tank will decompose and degrade over time. When Indian almond leaves begin decomposing in your aquarium, they release tannic acid which lowers the pH level.

Depending on your source of water and how many leaves you add to your tanks, you will see a range of pH levels.

So if you’re keeping softwater fishes that require low pH levels, then use Indian almond leaves in your aquariums.

Continue reading to find out how much leaves you need to reduce the pH level of your tanks.

2. Catappa leaves improve the quality of your aquarium water

I know it sounds weird to say that decomposing leaves in your aquarium will improve water quality, but it’s technically true.

Let’s assume you keep wild bettas, and good quality water equates with low pH with a fully cycled tank with no ammonia, nitrites, nor nitrates.

If you use Indian almond leaves to reduce the pH level of your tanks, ammonia (NH3) actually becomes non-toxic as it takes in additional hydrogen molecules to form ammonium (NH4).

Ammonium is non-toxic to aquarium fishes, so you are technically improving the quality of your water.

Now even if ammonium is non-toxic, it doesn’t mean that you shouldn’t do water changes in low-pH tanks. I don’t know if ammonium in large amounts is toxic as I can’t seem to find a source for it, but you don’t want to wait until ammonium reaches toxic levels – if any.

Another reason why catappa leaves improve water quality is that the decomposing leaves create more beneficial bacteria in your aquarium, which will help with the nitrogen cycle.

3. Indian almond leaves are great for creating a blackwater aquarium

Creating a blackwater aquarium? Indian almond leaves are a great and cheap source of leaf litter and tannins for your tank.

In Singapore, a big bag of 10-20 ketapang leaves in your local fish stores can cost as low as S$1 – more if you’re paying for a branded bag of catappa leaves.

To be frank, I see so many ketapang trees by the roadside and at the beach here in Singapore that I find it an excellent source for my tannin needs – though I don’t recommend picking dried catappa leaves by the roadside.

In Malaysia and Indonesia, the ketapang tree is so abundant (and not by the roadside) that many locals there get free Indian almond leaves all year round.

dried indian almond leaves in forest

I know most of my readers are from the US or Europe and ketapang trees may not be as cheap as it is here in Southeast Asia, but I believe it’s still one of the most affordable forms of tannins if you’re creating a blackwater aquarium.

4. Indian almond leaves encourage breeding – especially in betta fish

With the right water conditions – low pH, a blackwater tank, and ammonia in control – many fish, especially betta fish will be encouraged to breed.


Due to their natural environments being somewhat challenging to replicate, many fish species have difficulty reproducing in captivity.

Dark environments are preferred by a wide range of fish, as they believe darkness can increase the chances of their eggs and fish fry (baby fish) in surviving.

For some wild betta species, without a dark environment (tannins, low light, places to hide), they won’t even try to breed.

So Indian almond leaves will definitely help if you’re trying to breed fish, especially betta fish.

Of course, you’ll need to make sure you feed your betta fish properly.

5. Indian almond leaves provide a place for your fish to spawn

If you’re looking to breed fish, then Indian almond leaves provide a perfect spawning ground for your fish.

As I mentioned in the previous section, the right water conditions will encourage breeding. But some fishes require a specific place to spawn or otherwise they won’t even breed.

For example, killifish require spawning mops to breed.

As catappa leaves provide places for fish to swim in between them, they will act as a spawning ground for some fish species.

leaf litter in shallow water

For example, I’ve had friends whose betta channoides preferred to spawn in leaf litter over caves provided.

6. Catappa leaves provide food and protection for baby fish

A fry tank – an aquarium dedicated to baby fish – is often filled with Indian almond leaves.

With so many leaves at the bottom of the tank, it provides hiding spots for baby fish. Although the fry tank doesn’t have any predators, it’s instinctive for baby fish to hide from them.

Having a litter of Indian almond leaves helps make your fry feel safe – in a fry tank or even in your main aquariums.

When Indian almond leaves start to decompose, infusoria, a form of microorganism begins to feed on the leaf.


You usually can’t see infusoria, but when an explosion in their numbers occurs due to decomposing catappa leaves, you’ll see many small white things floating in your aquarium. You’ll see them easily in blackwater aquariums.

Infusoria is one of the first foods that newly hatched fry eat until they get big enough to shift to other sources of nutrition – such as daphnia.

7. Catappa leaves have anti-fungal and anti-bacterial properties

Now catappa leaves, or ketapang leaves to many Southeast Asians, swear by its anti-fungal and anti-bacterial properties.

You may think that it’s actually just local beliefs and non-scientific. But I’ve actually done some research and read further on the anti-fungal and anti-bacterial properties of the catappa leaf.

This study, this study, and this study actually show that Indian almond leaves have anti-bacterial, anti-microbial, and anti-fungal properties. And its not only beneficial to aquatic life, but to humans as well!

So if you’re looking to prevent diseases in your betta fish or any softwater fishes you have, then add Indian almond leaves in your tank to prevent them.

Not only will the catappa leaves help with prevention, but it also acts as a natural treatment for many types of fish diseases.

One of the most common diseases that ketapang leaves are used to fight is fin rot, which can be both a bacterial and fungal infection.

8. Catappa leaves can be used as substrate in your betta tanks

If you want to save some money on substrate or just don’t want to add substrate to your betta tanks, then you can look to having a layer of catappa leaves as substrate.

In my post talking about why betta fish need substrates in their tank, I mentioned that substrates are recommended to reduce pH levels, improve biological filtration, and prevent your bettas from seeing their own reflections to reduce stress.

After reading this post until this point, you’ll know that Indian almond leaves can help with all of them.

Reduced pH levels, check. Improved biological filtration, check. Preventing reflections, huh?

With catappa leaves and their continued usage, over time, it will form a thick layer of leaf litter that acts as a substrate base for your betta tanks.

This will prevent reflections from the base of your aquarium.

Not only that, it’ll help make your aquarium look like a natural betta habitat. I suggest reading my post on where wild bettas live in the wild.

That’s where I share what a bettas’ habitat looks like – across Southeast Asia and its different biotopes – which are filled with thick layers of leaf litter.

9. If you keep shrimps, it’s a feast for your shrimp tank

If you keep shrimps or have shrimps in your betta tank, ketapang leaves will be a feast for your shrimps.

Once the leaves soften, you’ll see your shrimps gathered and munching on them for the days to come. It’s a cute sight seeing all your shrimps gathered to eat the decomposing leaf.

Cons of using Indian almond leaves

Well, I can only think of two cons of using Indian almond leaves in your aquarium – potential ammonia spikes and the mess it’ll create.

If you throw too many Indian almond leaves into a tank, and it has hard water with high pH levels, you might not have enough beneficial bacteria to convert ammonia from the decomposing leaves into nitrite and nitrates.

As mentioned, ammonia is toxic at higher pH levels, and without sufficient biological filtration, you risk potential ammonia spikes.

The second one is more of an aesthetic issue. When Indian almond leaves decompose, they start to break apart. When they break apart, these smaller pieces will float around the tank (if you have high flow or bottom-dwelling fish) and cause an unsightly sight.

This can be easily prevented if you remove them as soon as they start to break apart and replace them with fresh leaves.

What is the best way to use Indian almond leaves in my fish tank?

Before putting Indian almond leaves in your tank, always rinse them with hot running water to wash off dirt and debris, and to kill off any living microorganisms on them.

Dried Indian almond leaves will naturally float. At this point you have two options, let it naturally fall to the bottom of the aquarium after a few days, or boil it until it sinks.

Then, you can choose any or a mixture of the following ways:

1. Put the entire Indian almond leaf in your tank

After rinsing them in hot running water, you can chuck the entire Indian almond leaf in your tank.

Let them float and fall naturally in your aquariums for a more natural look, or place the already sinking leaf where you want it.

If it floats and you don’t want to boil them, stick it under a rock or piece of driftwood.

2. Shred the catappa leaves before adding them to your aquarium

The second option is to shred the catappa leaves first. Many aquarists prefer this method as they will release tannins faster, it’ll look more natural in your aquarium, and it makes your aquarium look bigger (if you have a small tank).

If any of the above is what you’re trying to achieve, feel free to shred the ketapang leave to the size you want it.

3. Make an Indian almond leaf extract

If you decide to boil the Indian almond leaf, don’t throw away the brown water! It’s filled with beneficial tannins that you can use for your tank.

I will create a separate post on creating a blackwater extract, but the gist of this idea is to boil a bunch of ketapang leaves until the water turns a deep brown/black colour.

You may use the cooled-down leaves in your aquarium or dump them away, but keep the extract you’ve made.

With this extract, add them to your aquariums and during water changes. As you don’t know how much to add, you’ll need to test how much blackwater extract is needed to achieve the results you want – tannin-wise and pH level-wise.

Once you find this, make sure to use the same amount of Indian almond leaves every time you make this extract.

Is it necessary to boil Indian almond leaves before adding them to a tank?

It is not necessary to boil Indian almond leaves before adding them to a tank.

Yes, boiling the leaves will help to release tannic acids into the water. You can add this extract which helps to increase the tannin content of the water, which is good for the health of your fish.

Boiling also kills off any bacteria and other organisms that are present on the leaves.

However, there is no harm in using unboiled leaves. You just won’t get the full benefits of the catappa leaf when you boil them.

That’s why I recommend running them under hot water, which will help kill and wash off any bacteria or organisms present.

If I use too many Indian almond leaves, what will happen?

Using too many leaves will lower the pH level of the water to dangerous levels – especially if there is nothing to buffer the water to the pH level you need.

Some people, including myself previously, use distilled water when making water changes to maintain low pH levels. However, when you use pure distilled water, there are no minerals in the water to buffer it to a certain pH level.

This means that the pH can slowly drop to levels that you unintended for. That’s why it’s important to mineralise distilled water, but that’s for another post.

If your water is soft, or you’re using distilled water, be careful to not use too many Indian almond leaves.

If your water is hard, this shouldn’t be much of a problem. But it’s always best to test the pH levels of your aquariums, especially if you’re keeping sensitive fishes like wild bettas.

When should I use Indian almond leaves?

To recap, here are the reasons you should use Indian almond leaves:

  1. Indian almond leaves help reduce the pH of your tanks
  2. Catappa leaves improve the quality of your aquarium water
  3. Indian almond leaves are great for creating a blackwater aquarium
  4. Indian almond leaves encourage breeding – especially in betta fish
  5. Indian almond leaves provide a place for your fish to spawn
  6. Catappa leaves provide food and protection for baby fish
  7. Catappa leaves have anti-fungal and anti-bacterial properties
  8. Catappa leaves can be used as substrate in your betta tanks
  9. If you keep shrimps, it’s a feast for your shrimp tank

Indian almond leaves are great additions to your aquarium as they provide tannins, improve water quality, and give your fish some extra protection against disease.

They also have antibacterial properties, so they can help prevent infections from occurring.

So if any of the 9 reasons I mentioned above is what you want, then you should use Indian almond leaves.

Why are Indian almond leaves recommended for betta tanks?

Some betta fish species require very specific conditions to thrive. They need clean, fresh water with a stable temperature and pH level.

The ideal pH range for the betta splendens is 5.0 – 7.5. If the pH level drops below this, the fish may experience stress, and if it rises above this, they may suffer from skin problems.

Other species of bettas, such as the betta macrostoma prefer it to be between 4.0 to 5.7.

Thus, pH levels are one of the biggest reasons why Indian almond leaves are recommended for betta tanks.

But of course, there are other benefits that the catappa tree provides, such as blackwater, better water conditions, and its anti-fungal and anti-bacterial properties.

How low do Indian almond leaves change the pH level?

Depending on the water source you use for your aquariums and how many leaves you use, the pH levels will drop to different levels.

If the water you use is hard water, then it’ll take more leaves to reduce the pH levels. Usually, 2-3 big leaves in a small volume of water (10L/2.6 gallons) can bring the pH down to 6.0.

With the same volume of water and leaves, you can achieve a pH of 5.0 with soft water.

However, for distilled water or RO/DI water, I’ve seen pH levels go as low as 3.0 due to a lack of minerals in the water.

But before using Indian almond leaves to reduce the pH of your tanks, figure out how many leaves are needed to get to pH levels you want, then use that as a gauge in the future.

Different sources of water will have varying hardness and the effectiveness of catappa leaves will vary.

How long do Indian almond leaves last in the aquarium?

Generally, Indian almond leaves will last for about 1 to 2 months in the aquarium before they start to fully decompose.

This assumes you put a fresh catappa leaf in and it floats from the start, and that there are no shrimps or snails eating your leaves.

However, should you have boiled it, it will decompose much faster, perhaps in less than a month.

Between when you add the leaf until it fully decomposes, you are free to add or replace them to prevent it from messing in your tank.

What causes your water to turn a different colour after you add Indian almond leaves?

When you first add Indian almond leaves into your aquarium, the water will turn brownish yellow because of the tannin content. The more leaves you add, the darker your aquarium water gets.

Don’t like the brownish colour? Make partial water changes to clear the water up while still having the benefits of the ketapang leaf.

Want to get darker water? Add more leaves. Slowly.

Can I pick and use the Indian almond leaves on the floor?

Do not pick Indian almond leaves on the floor near roads or cities due to potential pesticides and fumes from vehicles. These chemical compounds on the leaves will kill your bettas.

This is the reason why I don’t pick up ketapang leaves from the floor in Singapore despite having so many trees around.

fallen indian almond leaves on road

Do not risk it, just buy it from the fish store.

However, if you live in the countryside where there are no roads, cars, and use of pesticides – say maybe in a forest – then feel free to pick up as many dried catappa leaves as you want, as long as it’s legal in your country.

What fish don’t like Indian almond leaves?

Indian almond leaves are not suitable for fish that love hard water or high pH. Many African cichlid species are naturally found in waters with high hardness and a high level of alkalinity.

If you’re keeping tetras, South African cichlids, betta fish, most of them prefer softer water and thus would like Indian almond leaves.

Why choose Indian almond leaves over other kinds of leaves?

There are two reasons why you should choose Indian almond leaves over other kinds of leaves – it breaks down slower and it has medicinal properties.

Leaves from Indian almond trees break down at a slower rate than those from other trees. There are big, tough veins on the leaves, and they take a long time to deteriorate compared to other types of leaves.

Because the leaf isn’t disintegrating into small pieces, you can easily remove it from your aquarium. That is if you didn’t shred it into small pieces before adding them in.

Furthermore, Indian almond leaves have medicinal properties – such as anti-fungal, anti-bacterial, and anti-microbial properties, that are scientifically proven – unlike other leaves that only give off tannins.

Indian almond leaves alternatives

There are many alternatives to Indian almond leaves, but do note that they do not have the same medicinal properties.

Here are four main alternatives to the Indian almond leave you can consider:

1. Peat

Peat is a natural product made out of decomposed plant matter. It is used as a substrate for plants, soil, and even used in aquaria.

Peat is strong and potent, and even just a small amount of peat can reduce your pH levels drastically.

Harvesting peat is not sustainable, so it’s not the best alternative to use to reduce your pH levels. But it’s still sold in aquaria and used by many aquarists across the world.

2. Alder cones

Black alder trees, native to Europe and the U.S., produce alder cones that look like mini pine cones. It is common to use alder cones as decorations and in shrimp tanks.

Similar to peat, alder cones are potent. My experience in using alder cones is that it leeches a lot of tannins, so even just a few might be more than enough for smaller aquariums.

3. Wood

There are many types of wood in aquaria, the most popular type of wood being used is driftwood. Other popular types of wood include bogwood and cholla wood.

Some wood leech loads of tannins while some will barely tint your aquarium water, depending on each individual piece of wood.

So if you’re looking for a reliable source of tannins and to maintain a stable pH level, this is not your best alternative.

Take note that not all wood can be used in aquariums, so don’t go around adding random sticks and barks into your tanks.

4. Oak or beech leaves

Dried oak and beech leaves are great alternatives to Indian almond leaves. They are not as strong as ketapang leaves, so you might need to use more to have the same effect.


Indian almond leaves are an almost must-have for any betta keeper due to many of the benefits it provides.

It reduces pH levels, releases tannins, encourages breeding, and provides microbes for betta fry to eat – a few of the many benefits it provides.

Furthermore, it’s affordable in many parts of the world due to it being easy to obtain. Thus, I recommend all betta keepers, especially those keeping wild bettas, to have multiple bags of it in their arsenal.

I hope this post has helped you understand more about Indian almond leaves.

Any questions?

Leave them in the comments below!

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