They are well known for their antibacterial effect which is comparable to Catappa leaves. These leaves also provide an important source of fiber, vitamins and minerals required by invertebrates.
Similar to the Catappa leaves, Black Guava leaves tend to float on the water surface for a few days before sinking. Some hobbyists prefer to slightly boil the leaves before use. The leaves are then left to rest for 10 minutes before adding them. This is entirely up to you as our leaves are naturally dried and collected from trees without any exposure to pesticides.
The Black Guava leaves release tannins and other ingredients into the water column of a number of weeks. They are not readily available for consumption by invertebrates as the leaves soften very slowly. You can leave the Black Guava leaves in the aquarium until the decomposing leaves are consumed by shrimps, crayfish, crabs or snails.
We typically recommend to add 1 or 2 Black Guava leaves for every 10 to 20 L of aquarium water.