Sue,
I have some that do the same thing. When I first got them and they started doing the cupping thing I freaked out thinking they ate one of our gobies

All fish were accounted for and I don't worry about it anymore. I know that they are getting plenty to eat when I see them cupped like that. Now if you buy the elephant ears mushroom you will have reason to think they may have eaten a fish. These get HUGE and will eat fish. I don't know if any club members have any, I don't think anyone wants their fish eaten.
Good to hear your tank is doing well
