Exciting pickup... have questions

[c0mf0rt]

I was at my LFS today and happened to run across a decorator crab.... the guy at the LFS gave me skinny but I was wondering what if any problems I will have with this guy.... He's already about 3" across (from leg to leg) I'm mainly worried about my fish (namely my psycho goby) and my small inverts.... I understand he might mess with my sponge or possibly my shrooms a little to camouflage himself and that's alright... but I'm worried about him attacking other things in my tank...... any help or advice would be appreciated... thanks.

[darb2]

If I remember coretly, they will cut off sponges, shrooms, and such and hide under it as camo. They also may catch small fish. At 3" I wouldn't add one to my 75. I would be worried that it would be too destructive.