Bad acro crabs?

[Peter Eichler]

What's your guys experience with crabs that eat SPS rather than form a nice little relationship with them? I've personally owned one crab (that came with the SPS) that I knew for sure was a problem and IIRC he was furry rather than your typical porcelain crab. Have some of you out there had problems with your more typical porcelain acro crabs?

Thanks,
Peter

 

[Peter Eichler]

Well I just went to take some pics of my new additions and upon further examination noticed I'm the proud owner of not one but 3 crabs in my new acro.

Here's why I'm concerned, I got the coral today and here around the base tissue is missing. At first I thought shipping stress or the start of RTN. Then the more I thought about it the more I felt it was a predator.

So, 2 of the crabs are of the normal porcelain variety. One is lookin a little furry... Kinda funny because the only reason that made me think a crab was the problem is because the one coral here I had the "bad" crab showed similar characteristics.

Here's the best pic I could get of the number one suspect. He's looking pretty guilty to me.

What do you guys think? I'm thinking he has got to go.


Also, what would you do if vendor sent you an acro on this state. As of right now they're telling me to keep them updated. However, I'm really not happy that the entire base of the coral is eaten away.

 

[clkwrk]

blue eye guy is bad but tissue is rtning . They eat tissue but it dosen't flake off like that. I would take a frag from the top side JIC it is rtn

 

[dots]

I don't even chance it with acro crabs anymore, I check them all before adding them to the tank and pull off any crabs I find.....given that craps are oppurtunistic feeders, I don't think its worth the risk.......what benifit are they to begin with?.......I say, fish food 'em!!!

Green is usually a phophate issue........

 

[JR719]

I also pull them off now. I wound up with a little blue eyed furry guy that was bad news. Once he was removed, the coral he was on improved.
From the looks of your pics, also appears you have either rtn or stn on the coral.

 

[Wonder]

the last pic is 100% a bad crab and i saw them eating polpy. around 4-5 polpys/day depending on sizes. The bad crabs are usually the ugly ones .

Other Accro crabs are good for sps as they will helps to clean & protect the colony

 

[Peter Eichler]

<a href=showthread.php?s=&postid=8280000#post8280000 target=_blank>Originally posted</a> by Wonder
the last pic is 100% a bad crab and i saw them eating polpy. around 4-5 polpys/day depending on sizes. The bad crabs are usually the ugly ones .

Other Accro crabs are good for sps as they will helps to clean & protect the colony

Yep, later today he's a goner. I couldn't find a pin or toothpick lastnight to attempt to get him out.

 

[RichConley]

<a href=showthread.php?s=&postid=8279892#post8279892 target=_blank>Originally posted</a> by sacramentodots
I don't even chance it with acro crabs anymore, I check them all before adding them to the tank and pull off any crabs I find.....given that craps are oppurtunistic feeders, I don't think its worth the risk.......what benifit are they to begin with?.......I say, fish food 'em!!!

Green is usually a phophate issue........

Pretty much everything we keep is an opportunistic feeder. Dont kill the good acro crabs, chances are someone wants them, even if you dont.

 

[Peter Eichler]

Well I got him out last night. Lets hope the coral doesn't have other issues and that it recovers.

 

[CalvinC4S]

By looking at the photo, that has been happening for awhile and not the crabs doing.

 

[mm949]

ive seen those blue eyed crabs devour a tennis ball size acro in just a few days....

i would snap off any dead or dying branches asap...

if it was the crab u should see improvement in few days..

 

[n8ureman]

IME everytime I`ve had a crab on any of my SPS corals I would evenyually loose that piece. At first I didn`t think it was the crab and when the coral died I "moved" the crab thinking it was harmless...lost that piece too. Now I don`t allow any crabs that I find on my sps to stay. All the crabs I have found have been the porcelan type and not hairy as well.

 

[cardona]

the pics of the crabs on your acro are the bad crabs, they are the ones that with eat your coral. others that look white and have no fuzz with a black bar across there eyes are the good ones. mine gards my acro and starts waving about when a cleaner shrimp comes by, i also wach him pick off detritis and brine that settels in the collony. but i would get those ones out asap

 

[RichConley]

<a href=showthread.php?s=&postid=8288254#post8288254 target=_blank>Originally posted</a> by n8ureman
IME everytime I`ve had a crab on any of my SPS corals I would evenyually loose that piece. At first I didn`t think it was the crab and when the coral died I "moved" the crab thinking it was harmless...lost that piece too. Now I don`t allow any crabs that I find on my sps to stay. All the crabs I have found have been the porcelan type and not hairy as well.

Have you ever bought a wild colony that didnt have acro crabs? How did it fare?

 

[oligotrophic]

It is a common sight to see Commensal crabs in wild imported colonies. These crabs do not pose any harm, in fact it has been documented such crabs protecting their coral hosts. For those who have been in this board for a while, there was an old pic of a commensal crab emerging from it's host colony extending its pincers to stave off a large black Crown of Thorns starfish attempting to attack the host coral. That Crown of Thorns starfish was several times larger than the coral and crab. Someone called the picture "David and Goliath"
That video came out from the BBC, I think. I do have the pic but it's kept in the archive, got to search...

Only the hairy crabs munch on coral polyps and tissue. And even for this case, in my tank I keep some dead colonies as coral rubble and notice the hairy crabs move on to and only live in the dead colonies as they devote their lifetime munching on the skeleton. They appear to have powerful pincers to pick on the dead coral skeleton. They appear more like calcium carbonate eaters than anything else. Just like some of the other fishes and turtles in the reef (with strong snouts) that munch off the branches of stonie corals

I get more free flowing zooplankton in the water column when the crabs mate, not that it is a lot but I think it does contribute to the well being of the tank. Just like in the wild there are commensal crabs so it should in our tanks, do not ignorantly remove them all.

Happy reefing