Also when this happens to my fish or if i receive them this way i cycle the feeding schedule of blood worms then brine shrimp then earth worms. Rinse repeat till its better. Maybe i just have freakish fish or maybe its my water but every time its a SA/CA Cichlid not an african they heal faster then what i think should be possible, but as the previous poster said clean clear water is a must to have it regen fast and all the way.
Just as an example one of my Oscars just got destroyed. He lost about 40% of his side scales on each side and his fins were twice as ragged as the one you have. 4 days of melafix later and he is only missing about 4 to 5 scales on each side and only has one split in his rear fin all the rest has healed completely.