I don't have a specific number for you but they eat more than most people realize. See Oojak's recent posts about his six line wrasse quickly depleting what he thought was an overabundance of pods.
sometimes it just takes them a while to get used to new foods. when i got my 29g it came set up with an adult true perc. the first few times i fed him frozen foods he spit them out. i added in some garlic extreme and bam he started eating it. now he's into my schedule of flake in the morning and frozen at night.