It's a standard sized female fiddler so 1-1.5" across. At first I just put it in to let it hunt or allow it to go after it itself but it showed no sign so last night I took forceps and offered it but it did not suction on to it at all. I then took it out and put the live feeder fish in and it grabbed one of the "marine feeders" as it was swimming through it's dangling arms. I don't remove the claws of fiddlers since all the other cephs don't have any issues and aggressively snatch the crab from the the top of the shell and if I offer it to them I make sure they can grab onto it from the top to quickly bite and paralyze it and the only reason I don't remove the male fiddler's claws, if it is a male I'm feeding, is because that holds a lot of meat inside the claw. However, this one does seem to be actively going for anything but I'm thinking of going and trying to get some small live shrimp or emerald crabs later. (I attached pics of the crabs and the what's left from feeding the baby CROs which are smaller than the Mimic.)How big was the crab? Did you remove the pinchers before you offered it to the octopus? When you fed the crab to the octopus, did you just leave it in the tank or actually present it to the octo?