Are Indian Almond Leaves Good for Aquarium Fish?

Have you ever seen a stack of large, dried leaves at the fish store and wondered what they are for? Indian almond leaves (IAL) or catappa leaves come from Terminalia catappa, a tree that originates from Asia and Oceania but now grows in tropical and subtropical regions all over the world. Its fruit seeds are similar to almonds. The leaves of Terminalia catappa are used in herbal teas as well as traditional medicines.

The Indian almond tree bears fruit and leaves

A dried catappa leaf can slowly decompose in aquarium water and create tannins. These plant-based substances gradually lower the pH level and give the aquarium water a yellow-brown tint. Although many people don’t like the natural tannins produced by leaves or driftwood, chemical filtration can be used to remove the brown tint.

What do Catappa Leaves serve?

If you have sensitive species (like crystal shrimps or certain South American seafood), then that preference may not be honored.

low pH and soft water

Indian almond leaf can slow-release tannic acids, humic and fulvic acids as well as other organic compounds with low acidity. They are slower than pH buffer chemical, but they have a more gradual effect that is considered “safer” as they are less susceptible to causing deadly pH swings. The leaves have a negative impact on water chemistry and are not recommended for use by high-pH fish such as African cichlids or many livebearers.

Some soft water fish can live with low pH, but breeding and raising eggs may be easier if the water is made more acidic. Breeders also use catappa leaf with Apistogramma citillas and betta fish (both wild-type and Betta splendens). Also, since the leaves float for the first few days, betta fish and gouramis sometimes create bubble nests underneath them for additional support.

Betta fish kept in aquariums with tannin-tinted waters

The antibacterial, antifungal and mild antifungal properties of Indian almond leaves is something that’s been noticed. Tannins are found in nature to help plants resist the attacks of bacteria, fungus and other pathogens. Scientists continue to study their potential use in medicine. Catappa leaves are a popular choice for aquarists to aid in mild ailments and to boost fish immune systems. Tannings may be beneficial for betta fish who bite their tails. Many experts also recommend that you add tannin-rich leaf or alder cones to your eggs in order to combat fungal growth.

As the Indian almond leaves soak in water, microorganisms consume it and then break it down. They reproduce quickly and develop into layers of biofilm, infusoria. This microfauna is a good food for tiny shrimps and fry. Sometimes, it is the only food small enough for them. If you have no one to feed your shrimp colony when you go out of town, soak several leaves in a bucket full of water for three week until they are slimy with biofilm. Then drop them in your aquarium as a long-lasting vacation food while you’re gone.

Blackwater is a biotope aquarium that imitates the Brazilian forest stream

Finally, if you want to create a South American biotype or blackwater aquarium that simulates your fish’s natural environment, use lots of catappa leaves and other botanicals to cover the ground. This makes brightly colored fish, such as neon tetras or cardinal Tetras, stand out. Because they are less visible from the tank’s tannins, it makes skittish fish more comfortable. A sufficient amount of Indian almond leaf litter can provide hiding places for fry or shy bottom dwellers such pygmy cydoras.

How to Use Indian Almond Leaves

If the dried leaves are very dusty or dirty, you can gently rinse them in water first, but the catappa leaves sold by Aquarium Co-Op are clean enough that we just drop them directly into the fish tank. They usually float for the first 3-7 days, so if it bothers you, weigh them down with a rock or decoration. Also, you can break the leaf in half to just use part of it or crumble it into smaller pieces to speed up the decomposition process.

Dried catappa leaf, ready for use with aquariums

How long should I use catappa leaves? One leaf is approximately 4-7 inches, or 10-18cm in length for every 5-20gallons of water. For blackwater tanks, you will need to use more leaves and other soft woods (like Malaysian driftwood or chollawood) until you get the desired color.

Should I boil Indian Almond Leaves? Boiling them will release all their tannins so they won’t give you any benefits. Some people prefer to make a catappa herb extract. This is done by boiling one of the leaves for every 0.5 gal (2 liters), of water. (Make sure to use a cheap pot you don’t care about because it may become stained.) Once the liquid has cooled you can add some to the tank until you get the desired color. To dilute too much extract, you can simply add more water to the tank.

When is it time to replace catappa leaves? Catappa leaves usually last between one and two months before they completely fall apart. To give the leaf time to begin breaking down and release tannins, add another leaf if you notice holes in it.

Caridina cantonensis shrimp munching on the remains from a catappa leave

If you are thinking about keeping shrimp or breeding softwater fish, or creating a blackwater biotope for your aquarium, grab some catappa leaves. Aquarium Co-Op leaves can be used right out of the packaging, because they are already cleaned.