I found this thread that might help you
I just wanted to post this to say I beat Duck Lips. My flowerhorn looked healthy as ever He's about 6'' inches. I decieded to breed him, all was going well but the stress of cleaning the clay and the whole courtship thing probably brought this on, as it did the same to my other two flowerhorns...
www.monsterfishkeepers.com
I don't have any experience with this disease myself, but I looked it up and have heard people say Kanamycin works well, as does swabbing the fish's lips with mercurochrome. A lot of people also say they put their fish in a salt bath/dip and that they have melafix and metronidazole in there, too. I don't know how well any of these would work, but these are just some options to look into