In the past I have used orange peels. Yesterday I dropped one in. Today we have all kinds of appetite. The 5 already had good appetites to begin with so I have no measure of what the peel has accomplished yet one of the fish is trying to eat the peel. If nothing else you will get the benefit of the nutrition that the orange itself gave you by you eating it. Try a small bump up in temp, a tiny water change, a pinch of peat moss in the filter, and the peel. Most discus seem to relish freeze dry black worms.