More hitchhikers - Crabs aren't that bad...

[Quinn]

I'm big on the innocent until proven guilty notion with hitchhikers. I thought some of you might be interested in the following.

As some of you know I've stumbled upon some interesting hitchhikers since I bought my Kanai live rock last summer. Two weeks ago my sister alerted me to the existence of two crabs in my live rock. I got a good look at them both last night.

One is orange-brown with yellow-brown stripes, about two inches wide, and significantly wider than it is deep (from front to back), and is living in a hole in a large slab of rock, a hole that my bicolor blenny has been using since I bought him soon after the rock. It would appear that the crab is slowly making the hole larger and larger, as I am now noticing that it is progressively widening. The blenny hasn't suffered in any way during this time. Within two inches of this rock are two very nice Acropora sp. frags. Neither has ever had any indication of being predated.

The other crab is living about nine inches away from that, in another hole in another rock. He is extremely flat and a little smaller than his counterpart, and is black with white areas. He has the ominous red eyes and was eating algae last night. About an inch from where he was sitting is a small yellow Acro frag which has grown significantly since it was given to me about the size of a pencil eraser. No signs of damage in the three months I've had it.

I cannot deny that I have lost a lot of snails, roughly 80% of the original 30 (now supplemented with almost 20 of different types). However considering I see these snails on their backs often, I expect this is the major factor in their expiration.

I don't think all crabs are safe, and I am sure these two would become a problem if they were so motivated. But at this time I feel that their food needs are being met without attacking my livestock or pruning my corals. I have to admit I was tempted to remove the black one, as it would have been easy to do. But I chose to leave him. We'll see what he's up to this evening.

[LostMind]

nice. You must have received an excellent shipment!

My rock was a bit on the dry side, nothing could have lived thru it

[Jack]

I've had a few crabs and to be honest I'd rather not have them in my reef.

I think a lot of reefkeepers play the guessing game when it comes to these crabs, especially ones in our acro's. I've seen some crabs eat pollyps and tissue and others that were completley harmless. I just take any crabs I find in my tank out when I see them. I don't think they add much in the way of biodiversity anyways.

But, I do like porcellain crabs.

[Chad]

I have two crabs, one a light blue with the red eyes and one that is black and white.. I have never really gotten good looks at these two.. I have tried to capture them as well with no luck.. I've pretty much just given up on them and let them be. No harm no foul right..

[Samw]

I have a red-eye brown crab with dark brown tipped claws and lots of spikes on its body that I've been trying to catch.

[Bob I]

Originally Posted by Chad

I have two crabs,

Ouch. you need blue ointment.

one a light blue with the red eyes and one that is black and white.. I have never really gotten good looks at these two.. I have tried to capture them as well with no luck.. I've pretty much just given up on them and let them be. No harm no foul right..

[Chad]

Originally Posted by Bob_I

Ouch. you need blue ointment.

Yeah, no kidding eh?