emerald crab

Hi, I was wondering if it would be okay to put a single emerald crab in a 2.5 gallon tank? I had to move him out of my 40 gallon because he was trying to eat my cc starfish, and my only other sw tank has 2 eels. I had an empty 2.5 that I filled with tank water from the 40 that he’s in now. It...