You might want to check out the thread:
https://www.reef2reef.com/threads/poll-how-many-reefers-have-successfully-kept-a-butterfly.543544/
Check out
@ReefTeacher posts there as well as mine... Quick answer and more later is that I've been successful with all of the following in my reef tank. The only items they get are the frogspawns and oddly enough there is a single frogspawn they have left alone. Second qualifier, they are fed well: chopped scallops and shrimp in Vitachem and Selcon plus chopped clams on the halfshell. Contrary to a previous post on the above thread, lately have had problems introducing new fish and have noticed some subtle and not so subtle aggression towards new additions (Yes
@Devaji was right!). Here is a video of them eating
https://photos.app.goo.gl/KWoTADvWicdhxUcy7
Indian Ocean Vagabond Butterflyfish - Chaetodon decussatus
Pebbled Butterflyfish - Chaetodon guttatissimus
Lemon Butterflyfish - Chaetodon miliaris
Spotband Butterflyfish - Chaetodon punctatofasciatus
Yellow Longnose Butterflyfish - Forcipiger flavissimus
Double Saddle Butterflyfish - Chaetodon ulietensis
Latticed Butterflyfish - Chaetodon rafflesi
Klein’s Butterflyfish - Chaetodon kleinii
Pearlscale Butterflyfish - Chaetodon xanthuru
Pakistan Butterflyfish - Chaetodon collare
Singapore Angelfish - Chaetodontoplus mesoleucus