I have a hermit just like that and he's done fine in my tank. When I bought him, he was about 1/2" and has grown quite a bit. He hides most of the time during the day and comes out at night. The smaller ones I have are out all the time.
I suspect that the small ones are more vegetarians, but when they get older, they like the copepods that come out at night...but I haven't caught him eating any of them.