[oscar c]

do emerald crabs eat sps?

[Ninong]

oscar c,

I don't know how you ended up over here in the SPS Coral Database, I guess someone moved you here. But since your question is about Emerald Crabs and since no one is paying any attention to you over here, I'm moving you back to the Reef Aquarium forum.

Hopefully someone will notice your post there.

[Ninong]

oscar c,

Here are a few comments from previous threads on Reefland about the feeding habits of Emerald Crabs:

"Emerald crab eating my candy cane coral !
thought my candy cane coral got "stung" from falling near my anenome ( looked a little retracted after i put it back in place) in a few more days i saw that a few stalks were white and "clean".then today i passed by and looked around the tank like i always do , to check up on everyone. noticed the biggest of three emerald crabs i put in 2 wks ago (to control bubble algae) ,was picking and eating the polyps!!!! moved the candy cane to another location in the tank (hope it's too lazy to look for it ) darn thing IS looking pretty fat and sassy!" -- junkzoo, 5/13/01


"I had two that didn't bother any of the livestock but seemed to eat nothing but coralline algae. I didn't like the bare spots on the rock so I got rid of them." -- Iron Crab, 4/28/02

"I've had emeralds off and on for 2 years. I've never noticed them eating coraline. I did have a bubble algae problem, now I don't! I did have one last year (VERY LARGE) that attacked and ate all the stalks of one of my colts. The colt recovered, he didn't." -- Scout, 4/28/02

"I got 3 Emeralds for bubble algae... had a little patch that never really grew... but the little buggers have been very, very busy scraping my LR down to nothing. I have managed to catch one of them (he is now in the Q tank munching Nori every once in a while). They are incredibly "smart." I would not put them in -- they have completely stripped all my LR -- and I could have lived with a little bubble algae." -- WannaBeAReefer, 4/30/02

"I had 4 in my 150, 3 have died over the last 6 months. They all ate coralline none stop, didn’t touch the hair algae." -- wperrette, 5/2/02

"I had two emeralds that ate a lot of algae when they were small, but they grew fast and then they got destructive. When I caught one snapping the ridges off my bubble, they were outta there." -- addicted2fish, 10/22/01

"I believe "opportunistic feeders" sums them up best. When I first introduced 2 mithrax crabs to my reef they were fine and had some hair algae to eat. After the hair algae was consumed they started to pick at corals and even took a few swipes at fish here and there. I eventually had to remove them both." -- GregD, 7/9/01

"Evil emerald crabs!
I was watching the invert tank at the local fish store and i watched one of these things attack and kill a small serpent star (that i want to buy none the less). I was also thinking about the emrald crabs to use as part of my clean up crew but after seeing that i am not sure, if they do that to a star fish i cant imagine what they would do to my tank! Anyone else have problems with these? I have seen them marketed as reef safe but i really dont think that is true." -- BTL, 6/5/01


"I come from the land of Mithrax crabs.
Bottom line, as juv. they love their greens and they have no manners. If you're trying to get rid of one algae and cultivate another forget it. As they get older their diet changes to more protein (reproductive thing). They love to look under things for food and they are very strong. Thus you're constantly picking up after them. Oh, did I mention how fast they grow.
HTH
Jerel" -- 2/8/01

Perhaps someone will post if they have witnessed Emerald Crabs attacking SPS in particular.

Here is a post by MiNdErAsR on Reef Central 4/8/02:
"Sorry Skip, but I have to disagree with you on the reef safe part. IME Mithrax sculptus may go for a year or more scraping algae from the liverock. However, being an omnivore and an opportunistic feeder, they will eventually turn to the dark side. Once I discovered mine eating the flesh from one of my acropora, they were promptly banished to the sump. This was in my old tank. In my new system all clean-up duties are performed by snails, conchs, and cucumbers. No more crabs for me, of any kind."

Here is a post by smiller on Reef Central 1/13/02:
"I have an emerald crab that has fallen in love with a 3" horizontally mounted tri-color acro. After dark I have seen him perched on it at least half of the times I have checked. Doesn't seen to pick at it-just hanging out. The problem as I see it is that most of my acros (including this one) only extend polyps at night so this is at least part-time preventing the tri-color from doing so. I have tried to catch the crab the last couple of nights to move him out. Am I correct that this will cause a problem if I don't remove it? Thanks."

Here is a post by belling on Reef Central 12/5/01:
"I bought a little green acro frag a few months ago, and after a day or so I found it had been snapped right off at the base, and the coral was nowhere to be found. I have since banished three emerald crabs to the sump for other crimes against polyps, but I wonder if one of them could have snapped it off. Is coral snapping common for crabs?"

[asmith]

I don't keep SPS right now, but when I had them, I never had a problem with emerald crabs picking on them.

Andrew

[MtnDewMan]

I have had emerald crabs in my SPS tank for a couple of years and have never seen it eat SPS ... I do have one that likes to hang in SPS after lights go out ... but have seen absolutely no damage to the coral as a result ... here is a picture ...