Emerald crab question...

[jc74]

I bought 9 emerald crabs from this site a while back. They were all smaller than dimes, legs and all. I watched them float to the bottom and pick at some algae for a while, and that's the last I saw of them.
So about 2 months later I see one of them, and it's HUGE! I'm talking at least 50 cent piece huge with massive claws. It's the only one I've seen, so I guess the rest are either dead or deep in hiding.
My question is, will they kill each other? It seems odd that one is gigantic and the rest seem to have disappeared. I know they're algae eaters, but will they kill for competition?

 

[teen]

idk if they'd kill eachother, but the same thing happened to me. i got 3, all small. 1 got huge. the other 2 i still saw, but they didnt get as big. the only thing i would worry about is that if they get big enough and they're hungry, they will go after corals. ive heard of them going after things like yellow button polyps before. i took mine out because i didnt have any algae left for them to eat.

 

[jc74]

Correction, this thing appears to be around 3" wide from leg to leg. I've had emerald crabs before, but nothing like this. I'm getting hungry.

It's a deep, shiny shade of green and almost looks like glass. I also just saw another one for a split second and it's not much bigger than when I got it. That's the first time I saw two since I dumped them in the tank.
I didn't know about them eating corals. I only have one coral right now to see how it does after a copper purge. It's doing good so far.

 

[teen]

what do you mean by copper purge?

 

[rainmkr07]

I had 4 emeralds, the biggest tore the legs/claws off 2 of the smaller ones. I returned him to my LFS. So yes, it is my opinion that a bunch of the same-sized small emerald crabs together are fine, but when you have 1 of the large ones with other emeralds, he will attack them.

 

[donald]

they can fight if their are too many and not enough space. I have two in a 55g and they rarely meet but when they do the little one moves like lighting. I have one huge one and one regular one, It didn't take them long to figure out who runs the show. I would think that several of the same size would cause fighting, but if one is huge and the other small all they have to do is look and they can tell who's in charge. It works in my tank. Also both of mine are male

I'm looking for a female, hint hint