New Crab showed up in our tank

A new crab just showed up in our tank from a live rock which is a couple months old. He lives under an oster. He/she has hairy legs and black claws. I have tried to get pictures but he is shy. I believe he is a gorilla crab. Currently he is about an inch in diameter including his legs and claws.



I have read that this guy can be a problem for my inverts and corals. Here is my problem: My daughter has really bonded with him. She feeds him breakfast and dinner in bed!! He will come out and grab flakes or shrimp from her fingers and retreat to his liar under the oyster. Now, the second he sees a hand, he comes out regardless if there is food or not (briefly though).



If she continues to feed this guy, can we keep his bad tank activities in check??



At this stage, he seems awfully shy and is not harming anything in the tank. Will this change over time??



If it is a must to get him out of the tank, how do they do in a smaller tank?? Or is there some sort of crab rescue out there because I can not do away with him without risking my daughter's wrath!!



Other members of the tank include Algae blenny, chromies, Damsels, Oysters, sea urchins, hermit crab, turbo snails, mushroom and polyp corals.



Thanks for any help on this issue!!