hairy crab in acro

[90gal.newguy]

I just purchase a very nice acro that came with 3 squatters.
2 i have identified as acro crabs........ but there is 1 fuzzy, white eyed crab that is hanging around near the top of the acro.
I am sorry but I am unable to get a pic of him.
Any ideas what he could be and if he is possibly a good guy or a bad guy ?
Thanks for your help.

 

[Anonymous]

I always leave them until I see evidence of damage, most of the time IME they can be left alone...but not always. You're mileage may vary.

 

[90gal.newguy]

Then that is what I will do. Right now there appears to be no damage.
Thank you for your help !

 

[Charlesr1958]

I personaly would remove that crab as it is most likely a Xanthidae species that could very well be feeding on your coral's tissue and polyps. I have seen such crabs crush and then eat coral polyps.

An example of many such crabs:

A Hitch Hikers Guide to the Reefs

Chuck

 

[Anonymous]

Yeah, well removing it is the 100% safe thing to do - but I've had a number of them that were harmless. There are so many species, you just never know.


http://www.reefs.org/hhfaq/crustaceans/ ... =xanthidae

 

[Charlesr1958]

Any crab, that is not a coral commensal would only be on/in the corals to feed, either directly on the coral or for any food that the coral may have captured, unless the crab just happens to be passing through and nothing had caught its fancy, but in an enclosed system, its only a matter of time before something does catch its fancy.

Coral Crabs

Hitch Hiking Crabs

Chuck

 

[Anonymous]

That's my point, many of them are commensal. Also, not all of them get big enough to bother fish.

Again, depends on the species and there's been plenty of times that they've lived long term in my systems with no issues. If he wants to be 100% safe, he can remove it as I said before. :wink:

 

[Charlesr1958]

Many of what are commensal? The "hairy" xanthidae species? The truly commensal crabs or any of the commonly found hitch hiking xanthidae species are not a concern for fish, it is the coral's tissue and its polyps that are in danger from the free ranging crabs found as hitch hikers, unless of course a small fish makes the mistake of using a hole or burrowed out cave to sleep in and its crab owner catches it.
I think theres some confusion as to what are "coral crabs" and what are free ranging, ie destructive, crabs. The crab types that I posted a photo of above, is not in any sense of the word reef safe, fish safe, maybe, but for any sessile inverts, they pose a constant threat.
For me, there is no doubt that it should be removed.

Chuck

 

[90gal.newguy]

I have removed the crab as it appears as if he was eating my acro. I began to notice white / dead spots where the crab was.
**I did not kill him. I have another tank that only has live rock and some fish. There are no corals for him to munch on !!**