Okay...I've had hermit crabs. I can't understand why anyone would be afraid of them...what's the big deal? Just drop some food in there and a bit of water, if needed.
I'm sorry but I just wouldn't lug around an aquarium with some hermit crabs in it. If you have someone already coming to the house to deal with cats, then it really shouldn't be an issue to feed a few hermit crabs. I mean, come on...how big are they??