Dried Banana leaves are used by many betta breeders as an alternative to Indian Almond Leaves. While I am not aware of any pharmacological studies into the efficacy of the leaves for aquatic use, many Thai breeders believe that they are better than Indian Almond Leaves. They are said to enhance colouration and general health of bettas. They will not tan the water unlike Indian Almond Leaves, so they will be good for those who would like to have the water conditioning properties of the leaves without having to bear with dark colour water. It is also said that such leaves have the following effect:
* Reduce PH of water
* Anti-Bacteria
* Stimulate betta colour
LINK