Mean Hermit Crab!!!

[reefcat]

So when I established my tank 1 year and a half ago when I bought the first bit of my live rock a tiny little hermit crab tagged along. I noticed he wasn't blue legged but green with red antennas. Now he has outlived all my other crabs and is MASSIVE. He has been fine and doesn't bother any one and just cruises around and does his thing. Just today I got 1 small blue legged hermit and as soon as he hit the water the green hermit locked onto him like a heat seeking missile. He tried to pull him out of his shell twice even after I relocated the two. I have the smaller one in my coral-growing tupperware container for the night but thats not a lot of space for long-term. Are these green legged hermits bad because I can't even find any info on them.