Unidentified crab, please help

grafgever

New member
http://www.youtube.com/watch?v=Hgz3GGee3gc

In the above link, I have uploaded a movie of the crab which I have noticed lurks in one of my live-rocks. Last saturday I added 2 small goby's to the tank, a yellow one and a green one. The green one I never saw since adding it (might be hiding in live rock?) the yellow one however was visible every day until today. Could it be this crab has eaten it? The only time I noticed the crab was after I feeded the fish I noticed something moving in the hole of my liverock, since then I've been paying extra attention to it, and every time I feed the tank it moves partly out of it's hole for what I can only imagine is hunting for food.

Any suggestions on what to do? I can't easily catch the crab as it's always inside the liverock, also the liverock it's in is at the very foundation of my reef. Any advice would be greatly appreciated.
 
Your best bet is to trap it. Use a tall, smooth sided glass and bait it with a small piece of fresh fish and tilt it against the rockwork where the crab is usually seen. Most crabs are nocturnal so it'll climb in the cup during the night, but won't be able to crawl back out.

It's likely a species of xanthid. Xanthids are very destructive in our tanks. They'll eat just about anything they can catch, including sleeping fish. I lost three fish to a xanthid before I was able to trap it.
 
I agree with a type of Xanthid crab. Not all crabs from the Xanthidae family are bad. For example, Pom Pom crabs are Xanthids. There is something like 572 crab species in this family. They aren't all bad. Nor can they all be expected to behave in the same way. Most reefers would remove though. Try looking up Actaeodes tomentosus. Good luck catching this guy.
 
Your best bet is to trap it. Use a tall, smooth sided glass and bait it with a small piece of fresh fish and tilt it against the rockwork where the crab is usually seen. Most crabs are nocturnal so it'll climb in the cup during the night, but won't be able to crawl back out.

It's likely a species of xanthid. Xanthids are very destructive in our tanks. They'll eat just about anything they can catch, including sleeping fish. I lost three fish to a xanthid before I was able to trap it.

Thx thats a great idea. but how do I make sure my shrimp don't get stuck in there instead? Also could it be it's not agrgessive since it didn't eat my shrimp?
 
Thx thats a great idea. but how do I make sure my shrimp don't get stuck in there instead? Also could it be it's not agrgessive since it didn't eat my shrimp?

Shrimp can swim out but the crab can't ;) It could be a 'safe' one but it also could be that it has found other food for now before turning on the rest of the inhabitants. Best to trap it and then get a positive ID to be sure.
 
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