This is an old time Thai remedy some of you may have heard of, this treatment it is very simple, used much the same way as IAL (Indian Almond Leaves) added to the water and letting the betta sit and relax in his new bath. Treats pop- eye and has also been recommended for torn fins.
How to Use Dry Banana Leaf Treatment For Betta Fish
Add a few pieces of leaf in to a gallon of water, and bring to a boil, COOL it down to the correct temperature and add your fish. After a few days the water will smell bad and cloud up but leave the fish for another few days, usually six or seven days, now remove your fish and see the difference. Bulging eyes have returned to normal.