What are catappa leaves?
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 taste similar to almonds, and its leaves are commonly used in herbal teas and traditional medicines.
When you drop a dried catappa leaf into your aquarium water, the leaf begins to slowly decompose and produce tannins, which are plant-based compounds that gradually lower the pH and stain the water with a yellow-brown tint. For more details on the benefits of catappa leaves, read our full article.