Please do not use feeder guppies or goldfish
Buy some ghost shrimps or chromis/damsels like i do...How long have you had it?
Anything under 2 weeks i wouldn't worry yet ,or even expect it to eat from a stick..This is my second one..Had this one about a year,,before this one i had another species, a sargassum,,he died in a rock slide ,got squished
I took the same approach to feeding with both...They both ate frozen from a straw in under a week...Key is to get them used to the stick/straw IMO
..Good luck comb