unidentified creature

Ill definately get some pics on here...Thats is if I catch him, he is very sneaky.....

 

Hi Tim I am just putting in my 2 cents hope you don't mind!
When I set up my tank I purchased my live rock online (ebay) I put it in my tank after rinsing it several times and letting it soak in a bucket with a power head for around 3 days and then put it in my tank to cycle with the tank.
Well to my surprise I noticed that there were 5 crabs in my tank they were shaped like emerald crabs but they were more gray than green I didn't pay them much mind I just thought cool I got some free crabs with my live rock.
Well the little critters lived threw the complete tank cycle and I hadn't added any livestock to my tank for about a month after the cycle was over, All My water parameters were perfect so I went and purchased a xenia coral and 2 fire fish, After adding them to the tank the crabs made a be-line to the xenia and started ripping the polyps from it and eating them I took the xenia out of my tank and put it into my refugium and not long after that one of my fire fish was dead with a laceration to it's stomach, What ever these crabs were they made fast work out of the fish and would have consumed my xenia if I hadn't removed it.
I had to take all my rock out of the tank and look in every hole in it for the killer crabs, I had to pull them out with needle nose pliers and tweezers one ran across the floor and hid under my tank stand, I finally got it about an hour after and it was still alive. Well I hope what is in your tank is not the same thing as these things were vicious they were even going after the net and clipping at it when I un-successfully trying to catch them with it. ..................... John

 

If its always hidding in the LR cave, I doubt it's a mithrax. If the hole only has one entrance, you can cover it up with super glue or epoxy. I've speared crabs in holes before using a hyperdermic needle with ease many times. Don't risk it, get the bastards out. If it is a good crab, you lost $6 bucks, not a big lose, but if it's a bad crab, you saved yourself countless dollars.

 

Gresham, I agree get them out!!!! I did finally get the " Bastards" out of my tank and I will never put a crab in my tank. I have 6 hermits and I don't even want them in there but they haven't bothered anything ( YET ). :
The ones I had got what they deserved They were Trigger fish food LOL ;Dand you should have seen one of them hold on to the triggers mouth with it's claws trying to keep from getting eaten I took the trigger about 5 minutes to get it loose then it was gone. .......... John

 

Did it look anything like this?

 

Something like that but it had smaller claws and there eyes were not red. My LFS said that they look like baby soft shell crabs ................... John

 

thats exactly what the little bastard looks like. He however has burrowed several tunnels in the live rock. I need to catch him. Is that one of the crabs from hell?(the above pic?)

 

Self portrait Curt?