Catch the bad hitchhiker crab!

[Celine]

I notice a bad hitchhiker crab in my tank. I don't think it is a reef safe crab. It is around 1.5 cm big. It moved do fast and hides inside the rock.

 

Any suggestion on how to catch it, pls?

[SyCo_VeNoM]

is it one of these? http://www.chucksaddiction.com/hitchcrabs.html

when I added live rock I got 3 of them(1 of each of the top 3 ones they show pics of at that)... Easiest way to catch them I found was chase them into the liverock, and pick that piece out, and look carefully for them with a flash light, and poke em with a with a pencil they will scoot out into the bucket fast.

Some people I read also recommend dumping liverock in freshwater for a few seconds cause the hitch hikers generally will jump off.

[Whys]

I don't suggest fresh, but hyposaline isn't a bad idea. You only need to shift the specific-gravity a few points under 1.022, as long as the shift is rapid, a crustacean should react and run out of the rock. Use fresh and all sorts of little stuff you don't see living on the live rock will simply die upon contact.

[Celine]

Sorry, I failed to mention that I cannot move the rocks. All my coral attached to it. The crab is hiding in the hole inside the rock. I tried to poke it out but it moves to other hole, very annoying.

[halcyonism]

Google "water bottle trap." I used the same method to catch a rogue peppermint shrimp, works like a charm.