I dont know much about discus but i researched a lot on them because i was thinking about getting them. I had trouble with an adult angel who wouldnt eat so i put some fresh minced garlic cloves in the tank and with his food and finally he started eating it. I have an elephant nose and i heard those are even more sensitive than discus, and he likes the garlic also and i think it increases his appetite also. I have read many articles where discus owners always mix their food with fresh garlic cloves because it helps boost their immune system, get rid of ip and increase appetite. so maye the garlic will work, try half a clove.