Try angel and butterfly foods. They come in frozen cubes. They have sponge in them. The sponge provides somekind of coral protein. It may help, but unfortunately with most butterfly fish, will be short lived unless you feed it the live coral they require for long term health in captivity. Pakistanies eat small polyp stony coral such as acropora and are very expensive coral. Mix the angel and butterfly food with a bit of garlic (Kent Marine and Seachem have garlic additives). Garlic is an appetite stimilant and at the same time will ward off any potential external parasites. Try also offering live brine and ghost shrimp.
At work, we once had a red sea raccoon butterfly that only ate live bloodworms for awhile, then finally started eating other foods.
