The catappa tree is well-known in some tropical regions, and it has been consumed as a meal and used in traditional medicine for millennia. They're extremely common in India, and fish keepers have used them to add tannins to aquarium water in the same way as Catappa, Guava, and other plants do.
In an aquarium, catappa fruit leaves have a lot of antibacterial and antifungal capabilities. These leaves, like Mulberry leaves, provide great nourishment for fish and shrimp, as well as surface-growing biofilm, while also boosting breeding and lowering pH levels in your water.

Boil all botanicals for 60 minutes to remove germs, dirt, and debris. Allow your botanicals to soak in dechlorinated, ro or aquarium water overnight before placing them in the aquarium.

You can use the soaking water as dark extract since it contains a descent amount of beneficial tanins.