Emerald crab, guilty or innocent?

[jeffchapok]

So I picked up a couple of emerald crabs last week, as my tank is new and I'm having a lot of diatoms growing and my hermit crabs weren't keeping up with it.

They went right to work tearing it off and eating it. I've also been feeding pretty heavily, as I have a banded coral shrimp that I never see eat anything, so I wanted to be sure there's plenty available for him and the entire CUC. I feed mysis shrimp and occasionally a small piece of frozen fish, which usually goes uneaten for days.

So this morning I find the largest of the two emerald crabs eating what's left of my hairy red hermit, Eugene. The hermit crab was roughly twice the size of the emerald. He was my very first addition to the tank and had a lot of personality, and I'm quite disturbed to see him go out this way.

All I've read says that emeralds are pretty good tank mates, with the possible exception of snails, as long as they are well fed. There's certainly no shortage of food for them, as there are still lots of diatoms in addition to everything else I stated above. There's even still a piece of fish lying on the bottom.

Is it likely I've just got a bad actor and could he really kill a hermit twice as large as himself? The hermit seemed otherwise healthy up to this point, although he hadn't moved much in the past several days. I thought he was perhaps getting ready to moult.

The emerald attempts to grab at any fish that gets near enough, and I'm afraid he'll eventually kill my small Randall's goby and my banded coral shrimp. I guess the safe bet is to take him back to the LFS.

Thoughts?

RIP, Eugene.

 

[Florida Sunshine]

Are you sure the emerald wasn't eating the molt of Eugene?
Personally I am not a fan of crabs of any kind in my tank but I think it is more likely he was eating the molt, particularly if there is other food readily available.

 

[jeffchapok]

That was my hope at first, but no, it was definitely Eugene himself. He was pulling away pieces of flesh.

I'm going to have to stop naming my critters. It makes it too hard when I lose one.

I still have 2 mocha clowns, Bruce and Caitlyn
Blaze, a purple firefish goby
Diana, the Royal Gramma
Randy, the Randall's goby
Gina, a scarlett hermit crab
Murray, the banded coral shrimp
Fatman and Little Boy are the two emerald crabs

 

[new2reefin]

Emerald crabs......they're guilty until proven innocent. I blame them for everything that goes wrong in my tank. I re-homed one the other week and still have a second one to evict.

 

[S-t-r-e-t-c-h]

I guess I'll go the other way and say that emerald crabs get a worse rap than they deserve. The only ones I've ever had issues with were big males with massive claws. Female emeralds have been mostly fine for me.

I doubt very much that any emerald would kill a hermit twice its size. Those hairy hermits aren't push overs either. In fact, if there are corals in the tank, I probably wouldn't replace him...

 

[Triggreef]

Innocent. They won't let a carcass go to waste but probably not the cause.

 

[RussiReef]

In my book innocent.

 

[Katrina71]

I'd say guilty. Crabs are opportunistic.

 

[Khoi Mai]

My emerald crab ate my hermit. Then lots of my zoas. He was innocent at first but then turned evil...

 

[Nathan Milender]

I had 2, one is gone (possibly eaten by the second, at least I have not seen him for the past month). I have been struggling to get algae going in my tank again so it could be hunger but I make sure plenty of meat pieces get to the rock. The emerald was lurking on my new flower pot frag, i chased him off a couple times, today it is just red residue. I am pretty sure it was the crab. I managed to get some algae in there for him, and fed him seaweed (left over sushi ingredients). I think these things are crabs in every sense of the word, he will be taking a trip to the sump next time he comes out as he will flail his claws at the grabber so I should be able to get him. Snails may be the only safe bet, and even some of those can do damage if you are not careful.