Emerald Crab, Are they AGGRESSIVE

Z

zues2006

New member
Hello,

I've had an Emerald Crab for about 3 months now. I think he's a great addition to my tank. I've got a 30 gallon now. I've had a few different fish in the tank with him over time. A clown fish, a damsel or two, and a watchman goby. There's never been an issue with him and the fish in the tank. But, he's almost doubled in size since I've gotten him. Just this weekend, I've added a Coral Beauty to my tank. Within 30 minutes of letting the Coral Beauty free in the tank, the Emerald Crab took some swipes at the Coral Beauty and it looks like the Crab did a little damage/scratched/wounded the Coral Beauty. Have any of you guys known Emerald Crabs to be aggessive towards fish? I love the Crab, but if he's going to attack my fish, I'd have to part with the Crab. I've got lots of live rock for the Crab, and maybe I could set up my rock better, so that the Coral Beauty wouldn't swim so much through the rock (the crabs domain). Let me know your experiences with emerald crabs.

thanks,
 
I've got an emerald crab that does the same thing. Crabs are opportunistic. When I first added mushroom coral and green star polyps, the crab taste tested them a few times. I was worried at first, but after a few days he settled down. So far anything I add to the tank the crab is curious about it for a little while. I'm not sure if rearranging the rock will help, but you might try it. If it works let me know please.
 
The crab was just protecting it's turf.
And I have a very large one also and never had a problem.
The CB was new and didn't know where the crabs territory was.
That will change....
 
I was thinking of rearraging my rocks anyway, so we'll see if that helps things at all. I'd hate to lose my fish over a $10 crab
 
Do you need the crab? In other words, do you have an algae issue you are trying to deal with? Personally, I don't add crabs of any type to my system unless they are to serve a purpose. As gws76 stated, they are opportunistic feeders, and from what I've heard, can be hit or miss as far as problems are concerned.
 
<a href=showthread.php?s=&postid=11877841#post11877841 target=_blank>Originally posted</a> by dja1980
Do you need the crab? In other words, do you have an algae issue you are trying to deal with? Personally, I don't add crabs of any type to my system unless they are to serve a purpose. As gws76 stated, they are opportunistic feeders, and from what I've heard, can be hit or miss as far as problems are concerned.
Click to expand...

I don't have an algae problem, that I can see. I do enjoy having him in my tank though, he is a cool critter, that is untill he keeps attacking my fish. I'm going to keep a real close eye on the situation for a few days and see what happens. I was going to rearrange my rocks anyway, so I'll just do that sooner, rather than later (probably tonight). Crafy had given me some suggestions on how to orientate my rocks better. I'll try that and see what happens. If the crab wounds the fish again though, I'll put the crab in the other tank I've got untill I can get rid of him. We'll see what happens.
 
Scott, you SHOULD be allright, but as has been said, they are oppurtunistic and I don't like having them unless they are living in an acro. If you need to get rid of it, give it to beefy, his tank is full of crabs ;)

Have you moved your rock around yet?

I pulled out 3 pumps you can borrow, so stop by anytime...and I hope you are saving up for a MH fixture!!!

Keep an eye out for used equipment in this forum:

Used Equipment & Drygoods Selling
 
.......mine has been a model citizen..personally i like them they just look cool when they are visible...
 
I had one that attacked and killed a royal gramma shortly after introducing it and ate all my snails. That was the last crab I have ever put in my tank. I'm a member of the crabs are evil club!
 
Sounds like more people say that their crabs are not a problem, but after looking closer, everyone that said the crab was not a problem had a 40 gallon or bigger tank. I wonder if the size of the tank makes a difference. The crab might think a high percentage of the tank is his territory, and since the CB has less space to swim through, he is forced to swim through the crabs territory. I think I'll rearrange the rocks tonight and see what happens.
 
I had mine in my tank for about a year and he was good(he was 2.5 inches wide when i got him), recently i saw him eating my zoos. Sooner or later yours will do the same, but they usually only come out at night so that might be the reason many people think they are doing ok in their tank. Throw him in the sump.
 
I have a coral beauty that had wounds, nicks on her a few weeks ago. Freaked out thinking she was sick. After lots of info here, we thought maybe my clarki nipped @ her or maybe the frogspawn stung her. She has healed, although, I noticed a fresh nick on her side this a.m.
I have spent alot more time watching my tank & the clarki & frogspawn are not the problem.
I have a sally lightfoot (that I have seen grab @ my yellow tang, but only when she swims by her territory). I also have a mystery crab that hitch hiked in on a piece of live rock. He is purple w/ one HUGE claw that almost looks like a stone crab
::eek2: I have a feeling he is the culprit. Have tried to catch him, but he is way too smart :mad2:
I have heard as long as the crabs are well fed, there is usually not a problem. But their appitites get bigger as do they.
In my opinion, crabs in a reef tank are not a good thing. Do some research on the net & you will see.
Best of luck!
 
<a href=showthread.php?s=&postid=11885818#post11885818 target=_blank>Originally posted</a> by blumarlin
I have a coral beauty that had wounds, nicks on her a few weeks ago. Freaked out thinking she was sick. After lots of info here, we thought maybe my clarki nipped @ her or maybe the frogspawn stung her. She has healed, although, I noticed a fresh nick on her side this a.m.
I have spent alot more time watching my tank & the clarki & frogspawn are not the problem.
I have a sally lightfoot (that I have seen grab @ my yellow tang, but only when she swims by her territory). I also have a mystery crab that hitch hiked in on a piece of live rock. He is purple w/ one HUGE claw that almost looks like a stone crab
::eek2: I have a feeling he is the culprit. Have tried to catch him, but he is way too smart :mad2:
I have heard as long as the crabs are well fed, there is usually not a problem. But their appitites get bigger as do they.
In my opinion, crabs in a reef tank are not a good thing. Do some research on the net & you will see.
Best of luck!
Click to expand...

So you let a hitchhicker crab ruin your day,but all crabs in a Reef tank is bad news?
Me thinks you need to catch the hitchhiker crab.
They do have traps for that sort of critter.
 
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