Emerald crab size

[WhitePanther93]

So recently I’ve seen threads about emerald crabs becoming a problem once they hit a certain size.(usually after about 1.5 inches)

usually the problem is that they start attacking sleeping fish.

anyone here have any experience with this?
I’ve also read that emerald crabs usually stick to algae and detritus unless there’s a shortage of food.

Im just a tad bit worried after reading this information because one of my crabs has reached quite a decent size. A bit over an inch by estimation. And that’s just the body I’m measuring.

I think he was fighting his own reflection in this pic.

what do you guys think? Too big? Or am I just paranoid? I mean so far he’s been nothing but helpful.

 

[Sharkbait19]

I’ve never heard of them going after fish - any healthy fish can get away if it takes a swipe.
Coral and other inverts are another story, but keep it well fed and it will be okay.
You definitely have a male so I’m sure it’s gonna get even bigger.

 

[Mr. Mojo Rising]

same as above, I've not heard of them going after fish

 

[glb]

Will they go after LPS if there’s plenty of bubble algae to eat? I’ve also heard that females are better behaved than males but I’m not sure if that’s so.

 

[Sharkbait19]

Keep them well fed and it should calm them down. Crabs are unpredictable though.

 

[moz71]

I would remove if have corals. Mine ate a large chunk of my clam. Watched him do it and quickly removed. I can see them attacking a healthy fish though. Unless dying or dead

 

[WhitePanther93]

I would remove if have corals. Mine ate a large chunk of my clam. Watched him do it and quickly removed. I can see them attacking a healthy fish though. Unless dying or dead

Your clam may have been sick and dying, or your crab may have been a particular *******. Neither of my emeralds have touched my clam as for corals the closest I’ve seen them to bothering my corals is picking some algae off some frags. My big guy actually likes to use my hammers as cover.

 

[moz71]

Your clam may have been sick and dying, or your crab may have been a particular *******. Neither of my emeralds have touched my clam as for corals the closest I’ve seen them to bothering my corals is picking some algae off some frags. My big guy actually likes to use my hammers as cover.

No clam was fine and recovered nicely. It was a big dime size chunk he ate. Like all things in tank it’s a hit or miss on their particular appetite. If I didn’t catch in act probably would eat to death. This is why I wouldn’t take chance anymore. I am not claiming all will do it but fully capable. never again for me!!!

 

[bnord]

I sex the Emeralds and only add females - males left in store or in hte sump if they make it home
have watched them work over mini-goni colonies but am sure they are cleaning algae, as the coral is flourishing - heard people swear they attack zoas, but I have never seem it
AND only have bubble algae on places the crabs cannot access

so i like my system, but will not deny others’ concerns

 

[revenant]

That's a biggun. I too was a little worried about them going after sleeping fish but read they don't do that... also to keep them well fed and they should pretty much leave everything alone (reef safe)..

I have (had?) 5 emeralds in my 100G with a TON of LR and loads of algae to eat.. I have tons of bubble but the bubbles are very tiny so I assume the crabs and tang+foxface are keeping it trimmed back to only tiny bubbles.. the crabs were living in a very porous rock (lots of caves, tunnels) that my GSP has taken over but I haven't see them in months.. well, I did see one female about three weeks ago.. they NEVER are out during the day and I only see one sometimes at night with the red flashlight. I have tons of cloves, zoas, and palys and some LPS.. at this point I would welcome them pruning the cloves for me lol. I have no idea how many are left though..

 

[mcgallagherc]

Was looking at tank tonight and lights shut off, my firefish has his sleeping hole under a particular rock. Tonight 1 of my emerald crabs I just put in tank was in top of little cove fish sleeps in, fish headed in and was immediately attacked and came running out. It eventually got the courage to go back in as quick as possible and turned around to watch the crab(it always sleep tail end pointed out) was quite interesting to watch

 

[Goaway]

Was looking at tank tonight and lights shut off, my firefish has his sleeping hole under a particular rock. Tonight 1 of my emerald crabs I just put in tank was in top of little cove fish sleeps in, fish headed in and was immediately attacked and came running out. It eventually got the courage to go back in as quick as possible and turned around to watch the crab(it always sleep tail end pointed out) was quite interesting to watch

This is kind of funny, the emerald crab took over the firefish's home and kicked the firefish out?

Any update @WhitePanther93 on how yours is doing?

 

[SPS2020]

I had one even larger in my DT. One night, I watched him break off a tip of my red table acro. I thought either I saw it wrong or he mistakenly broke a piece off...until he did it two more times. He lived out his life in the refugium.

 

[WhitePanther93]

This is kind of funny, the emerald crab took over the firefish's home and kicked the firefish out?

Any update @WhitePanther93 on how yours is doing?

My emerald is still doing fine hasn’t caused any issues that I’ve noticed so far.

 

[alton]

The ones I have had I could see them eating algae everyday, never go after a fish. And clean up on the larger bubble algae that comes from the Atlantic, but never eat the smaller bubble that plagues every ones tanks. Now the crab pictured belong took out three fish in two years before I was able to locate and catch him. I gave him away to another reefer who had one and thought it would be nice to keep two, his crab didn't agree and killed mine.

 

[WhitePanther93]

The ones I have had I could see them eating algae everyday, never go after a fish. And clean up on the larger bubble algae that comes from the Atlantic, but never eat the smaller bubble that plagues every ones tanks. Now the crab pictured belong took out three fish in two years before I was able to locate and catch him. I gave him away to another reefer who had one and thought it would be nice to keep two, his crab didn't agree and killed mine.

What kind of crab is that?

 

[mcgallagherc]

This is kind of funny, the emerald crab took over the firefish's home and kicked the firefish out?

Any update @WhitePanther93 on how yours is doing?

Lol crab has evicted that spot and moved on with its life somewhere else