If you want a more natural habitat for your betta, consider a blackwater environment. Blackwater refers to the dark, murky water you might find in a betta’s natural habitat.
Bettas are found in slow-moving or still tropical waters like rice paddies and heavily vegetated marshes.
Using tannins in your aquarium to darken the water and raise the pH, you make a blackwater habitat. Bettas do well in slightly acidic water, so tannins are useful tools in your betta arsenal.
Tannins in betta fish aquariums come from driftwood and Indian almond leaves. The Indian Almond Leaf Tree is known botanically as Terminalia catappa and is native to the subtropics.
As the catappa leaves break down, they release tannins into the water. This makes it darker, softer, and slightly acidic.
Many aquarists claim Catappa tannins also have antifungal and antibacterial properties. The tannins anecdotally have immune-boosting properties and help prevent bacterial infections.
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Sources of Tannins for Your Aquarium
Tannins come from driftwood, decaying leaves, and plant matter.
Driftwood is a good, slow source of tannins, but make sure there are no jagged edges to tear your betta’s fins. Driftwood also encourages the growth of beneficial bacteria.
Beneficial bacteria process ammonia and nitrates and help keep water quality up.
Catappa leaves are the most well-researched leaf sources of tannins for aquariums. Some people also use:
- Catappa bark
- Acorn caps
- Alder cones
- Guava leaves
- Red oak leaves
- Peat moss pellets
- Beech leaves
- Savu pods
- Dried banana stems
Do not just throw any old leaf in your tank. Use approved, documented tannin sources for best results.
How Do Tannins Work?
Catappa leaves benefit betta fish by creating a healthy, more natural environment. The tannins make the water more acidic and softer, which the betta prefers.
Catappa trees are in West Africa, India, and tropical Americas and are considered invasive in many places. The trees are also called the Singapore Almond, Tropical Almond, and Sea Almond.
Indian Almond trees got this name because the fruit of the tree tastes like almonds, not because the tree produces almonds.
The tannins are released slowly by putting the leaf in the aquarium or steeping it in hot water to make betta tea. Tannin extract is also available but must be used cautiously as it is easy to put too much in.
Take care to balance the need for tannins in your betta tank with your aquatic plants’ need for light. It can get too dark for them, although your betta will love it.
When adding betta tannins, monitor pH carefully. This is important, especially if you have a smaller betta aquarium.
Tannins can cause quick pH changes, so always monitor your fish tank. This is good practice in general.
Tannins come from the phenolic acids in the leaves. They are a group of molecules that create an acidic condition when they are dissolved in water.
Making Tannin Extract
Making your own Indian Almond leaf extract is simple. You will need water, Indian Almond leaves, and a 2 quart glass jar.
Boil 2 quarts of water and add 1-2 Indian almond leaves to a glass jar
Pour the boiled water into the jar and leave the lid off for one day. Remove the leaves and place the lid on the jar.
Keep the jar in the refrigerator. It will be good for a few months.
Read more about Indian Almond Leaves and how they work with bettas in our article here.
Bettas naturally live in blackwater conditions in enclosed tropical pools or ponds and have plant matter decaying in them.
Blackwater also occurs in creeks or streams where the water has run through heavy vegetation.
Creating a beneficial blackwater habitat for your betta will give it privacy. Tannins are also said to help in breeding betta pairs during courtship and spawning.
Dropping catappa leaves in your aquarium creates a natural look. After a day or so, the leaves will sink.
They then break down and release tannins, which impart a brown color to the water. After about a month, only the leaf skeleton will remain.
To add Indian Almond leaf to your fish tank, start with 1 medium-sized leaf per 10 gallons of water.
Tannins are good for most tropical fish. They stabilize pH and create soft water.
Catappa and Your Betta’s Health
Catappa leaves are used in folk medicine and remedies in tropical and subtropical Asia. Catappa leaf tannins are healthy for fish, humans, and livestock.
The increased acidity from tannins can help eliminate unwanted microorganisms.
Many aquarists use tannins to speed up healing. This is because of their antibacterial and antifungal properties.
Sometimes aquarists use Indian almond leaves to treat illnesses, including fin rot and mild fungal infections. They use the leaves alone or with the medication.
Many pathogens cannot survive the slightly acidic environment catappa leaves create. Do not rely on this to protect your fish; however, use medication when indicated.
The tannins from these leaves are a good water conditioner, naturally reducing water and carbonate hardness.
There are no real negative side effects to using tannins except for the darker water. Some fish owners may not like it.
Tannins may also cause a too-rapid change in pH and need to be monitored. Overly acidic conditions may be harmful to your betta’s fins and scales.
Tannins and Your Betta’s Behavior
Tannins create a favorable environment for your betta, no matter the source. Use leaves or clean, betta-safe driftwood to create tunnels and caves for your fish to hide in.
Driftwood releases tannins more slowly than catappa leaves or other sources.
Catappa leaves release tannins within 24 hours. They usually only last a month before you need to replace them.
Betta fish owners know a happy betta will be calmer and healthier. Stress is a significant influence on health.
By creating more natural conditions, you are reducing stress on your pet.
Betta Breeders and Tannins
Betta breeders use tannins to create a healthy environment for their fish. Some claim tannins increase the ratio of male to female fry.
A happy, healthy betta is more likely to breed, so tannins are a useful additive.
Bettas also create bubble nests under the leaves. The leaves are big enough they protect the nest and the fry when they hatch.
Another benefit of Indian Almond leaves is they increase the presence of infusoria. Infusoria are tiny organisms already living in the water which feed on decaying plant material.
Betta fry are too small for regular-size fish food and feed well on infusoria.
Tannins and Dissolved Metals
Depending on your municipality, your tap water may contain varying amounts of metals. Metals are toxic to fish.
High metal concentrations in water damage fish’s gills. They will not be able to breathe adequately and become stressed and ill.
Tannins form hydroxyl bonds with metals in the water and help reduce metal levels. Metal concentration should be less than 5g/cm3.
How Do Catappa Leaves Impact pH?
Using tannins can lower the pH in your fish tank and make it slightly acidic. However, if your water has buffers such as high carbonate hardness, tannins will not affect the pH as much.
Bettas prefer a pH of 6.5-7.0 so monitor your pH if you use tannins. Rapid changes in pH are harmful to your fish.
Your betta will react if the pH levels get too low.
Signs of low pH levels in your betta tank include:
- Excess algae growth
- Fish loses color
- Sludge builds up on the substrate
- Fish acts stressed
- Betta staying at the surface or the bottom
Remove the almond leaves immediately if these signs occur.
Perform a water change and test your water parameters to ensure levels are up to par.
If you need a rapid increase in pH levels, adding sodium bicarbonate will do the trick. Add 1 tsp per 5 gallons of aquarium water.
How Do I Remove Tannins?
If you change your mind about using tannins or inadvertently use too much, they are easy enough to remove. Remove the leaves or driftwood source of the tannins.
Water changes will gradually remove the tannins from your tank in a gentle fashion. Activated carbon in your filter will also remove tannins.
There are commercial products for removing tannins.
Preventing tannins is also simple.
Soak driftwood ahead of time to remove the tannins. Use it in your tank after it has stopped releasing tannins.
To Tannin Or Not To Tannin
Tannins are a beneficial substance to use in your betta fish aquarium. They condition the water by making it softer and more acidic.
Tannins also make the water darker, which your betta will enjoy. This creates a blackwater environment more closely resembling the betta’s natural environment.
The use of tannins reduces stress in your fish by making them more comfortable. Stress lowers immune function and can lead to infection and illness.
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