I have this crab that I found in my 29g tank that came as a hitchhiker. He's dark purple in color, and his body is over an inch in diameter. I was wondering if he would be harmful in my reef tank. I have a few small acros, montis, zoos, LPS, and softies. The picture isn't the clearest, but I did my best to get a picture of him, because he's very difficult to catch.
