I currently have a sand sifting goby (decent size, 3 inches), and a mandarin goby. I was at my LFS and saw what they said was a "flower crab". I thought that he'd be great in the tank, except I'm worried that he'll bother the gobys? Any issues I should be worried about, or you all think he'll be okay? In the LFS, there were two crabs and they were kind of fighting each other a bit, but would hate for something to happen to my gobys.