Brown fuzzy acropora crab, blue eyes

Delphinus · #1 12-21-2005, 06:21 AM

I'll see if I can catch this guy and get a picture of him. In the meantime, I'll describe what he looks like.

Came as a hitchhiker on a Bali acropora, a few months ago. I think he's possibly developed a taste for acro polyps. A lot of my pieces are suddenly showing a lot of damage, and I was getting pretty frustrated, not knowing the cause (I thought I had lousy water quality). But tonight I shine a flashlight in the tank after lights out, and I see this crab (I see him every day, I knew he was in there), but this time it looks like he's feasting on an acropora. Hard to tell what he was eating, tank was dark, but it sure looks like the coral just sustained some damage. I tried to catch him but all I did was chase him away. Guess I'll find out tomorrow after lights out how bad the damage is.

Anyone have experience with "brown fuzzy crabs with blue eyes" ? Are these known coral munchers?

Definitely not the same as a "masked" acro crab, I have those too. This guy is always on an acro so he looks like a commensal crab, although in 3-4 months has grown from about 1/4" to 1/2" so I'm kind of thinking even the accelerated growth rate may be a cause for alarm.

Reefhawk1 · #2 12-21-2005, 09:23 AM

I only have experience with brown fuzzy crabs with red eyes. So many different types its hard to find out which crab is good and those that are bad. Brown with blue eyes probably bad

good luck on the hunt.

IslandReefer · #3 12-21-2005, 11:04 AM

Hey Tony,
I have always been a form equals function guy. Look at his claws and see if they are very sharp, fine and pointy like the red fuzzy "bad guys" or claws like the masked acro crab....or use the catch-em in the act method

.....or separate him with a test acro and see if he is the source of the damage.
Good luck and Top O' the Season!!

mr_alberta · #4 12-21-2005, 02:08 PM

Does that crab hang out in any particular coral Tony? An easy way to get him out would be an Interceptor dip...

BMW Rider · #5 12-21-2005, 02:42 PM

I got a Bali acro too earlier this year and it also had a brown fuzzy crab as a hitchiker. I removed it and tossed it into my refugium. I later determined that it was a xanthid crab, so I did the right thing. They are an undesireable type to have in your tank. I don't recall its eye colour (can't find it now to check), but the identifying characteristic were the black tips on its claws. I also have one of the acro crabs living in that coral, he stays since he is not harmful.

Delphinus · #6 12-21-2005, 03:58 PM

I thought about Interceptor too Harvey. I don't have any, nor have I spoken to a vet yet, so hopefully it doesn't have to come to that -- although I am accepting it as inevitable that eventually I will have to one day source some and do some treatments. In this tank I also have a porcelain crab, three peppermint shrimp, some of the "masked" acro crabs, and theoretically an emerald crab (although I haven't seen it in a few weeks now) so I'd have to catch all those guys and put'em somewhere else for a bit, if it came to that.

I'm thinking that since I can usually find this fuzzy crab without too much effort (it's always on an acro... not always the same acro, seems to "acro hop") so I'm thinking as long as I'm quick on the draw I can pull the whole colony out of the tank to catch the crab, rather than try to chase it around with tweezers.

The acro it came in on is pretty much decimated. I thought it was STN but I was unable to determine a cause, but now I wonder if it's just that the crab had his fill, and is now moving onto the others in the tank.

The thing that really threw me with this guy is the eye colour. They are most definitely sky-blue. Had they been red, I would have known not to trust it from the get-go. I don't know enough about crabs to know if eye colour is really significant, i.e., can there be variability of eye colour within species or not -- I don't know. It's so hard to do a search on RC these days so I hadn't even bothered trying to delve into it further. Last night was the first inkling I've had in 3-4 months that maybe I've made a mistake in judgment in trusting the crab would be harmless.

mr_alberta · #7 12-21-2005, 04:03 PM

I was actully hinting at removing the coral with the crab and doing an interceptor dip for a few hours...the crab should just fall out of the acro...dead.

Delphinus · #8 12-21-2005, 04:14 PM

Oh-- well, yes that would work too. Although none of my corals are so large that I think there'd be a problem picking off a crab with tweezers once I had the coral in hand and out of the tank. Unless he's so quick that he jumps off as I pull the coral out of the tank.

Delphinus · #9 12-22-2005, 06:38 AM

Caught him. Wasn't too bad, waited until well past lights-out in the tank, pulled out my hoeksemai where he was munching, flicked him into a container, put the coral back.

Definitely has the black tipped claws. I'll try to remember to snap some pics tomorrow.

mr_alberta · #10 12-22-2005, 02:09 PM

Quote:

Originally Posted by Delphinus

Caught him. Wasn't too bad, waited until well past lights-out in the tank, pulled out my hoeksemai where he was munching, flicked him into a container, put the coral back.

Tony!

Buddy....Pal!

P.S. Dibs on frags