I just added a piece of live rock to my girlfriends tank, and when I was unpacking the box there was a 1.5-2" crab in the box. My questions are will he be safe with the fish ( 1" dwarf lionfish, 3" gobie, and 4" porcupine puffer). I am not worried about the puffer as he might just eat the crab, but will the crab try to eat the other 2 fish. Also will he be safe with the soft corals and sponges?