I purchased a small Bamboo Shark a couple of days ago. He was eating at the LFS but not in my tank. Experience told me that sometimes these animals don’t eat not because they are not hungry, but rather because they do not like what you are offering.
Take my ribbon eel - refuses anything but LM prawns.
My shark - eats scallops, LM prawns and once in a while a piece of line fish.
My snowflake eel eats anything - squid, LM prawns, lance fish, krill, linefish, etc.
My zebra eel only eats LM prawns and krill. Will take one piece of lance fish but refuse any more.
My Bird wrasse eats anything.