Big Black Crab

[Ruth]

Yikes - I just saw this guy in my tank. He is black and about 1 inch plus across on his body - front legs are smooth and shiney and other legs are hairy. I don't know if he's bad or not but I want him out. This is the first time I have seen him so I am not going to be able to just grab him - besides my tank is too big and too much rock. What is the best way to trap a crab without catching any fish? I doubt very much that I will be able to get a picture before I catch him to help with ID but will take one if I am successful with trapping. Please help

[Johnny Reefer]

One way is to remove the rock that it's den is in, and try to extract it that way.
Or...Make a trap using the inverted pop bottle trick....
http://i23.photobucket.com/albums/b355/1Johnny2Reefer3/CrabTrap.jpg

Or...there are some commercial traps available for purchase....UltraLife’s “The Trap”. (pg. 84 of Big Al’s product guide)....or "TrapPest" by AquaMedic.

Or...just leave it.
I have at least 8 crabs (probably more), of various kinds, in my 135g.
I tried catchin' em with that bottle trap, but I don't think they even knew it was there. In my humble opinion, and based on my newbie reefing observations, crabs don't seem to venture far from their den. The crabs I have watched in my tank pretty much just munch on coralline algae right outside there front door.
Maybe I'll run into problems some day, but so far, IME, they are not a problem at all. (It's also much easier to leave 'em alone. As long as they behave).

JME & O.

Cheers,