That looks like an emerald crab, pads on its pinchers, not points. Shouldn't have been killing any fish. Good luck with the hunt!

I don't think that's an emerald crab, too fuzzy (emeralds are smooth). It's not a good crab but there's no way it's responsible for a tank of dead fish. You have something else in there. Yes, I would be setting a trap. I'm thinking mantis or larger crab.

Look for anything.

Scope out the tank at 4am in the morning and use a flashlight.

Alrighty I 'll give it a try. Thanks everyone

That sure looks like the work of a Mantis Shrimp to me.

My bro-inlaw had a crab that would pluck fish right out of the water and it wasn't surprisingly big. It plucked fish that were easily twice his size. Sinister...

But did he take all the fish in one night...prob not...crabs usually only take what they can eat at the time...so if it was one fish a night I could suspect a small crab....but all at once, definatly a crab thats bigger then a toonie!

Get a blue or Red LED flash light so you don't scare that predator away.. see you can find anything.. turn the light off at night wait an hour or 2.. and spy inside your tank

I didn't have any luck finding anything last night. I 'll try again tonight

Here is a couple pick of the claws that I pull off the crab while trying to get him out of the rock. Mabey this will help the ID.

Thanks Cody

http://i39.photobucket.com/albums/e1...d/PICT0003.jpg
http://i39.photobucket.com/albums/e1...d/PICT0006.jpg

Man, that thing is hairy.