emrald crabs - how dangerous are they?

[Reef Goalie]

I have a 75 gallon tank and have three emerald crabs in it. This seems to be a good number as what bubble algae I had is gone and has been in check since I added them. They vary in size from quarter to half dollar size. The big one is curious but has not eaten any of my polyps at all. They do occasionally walk over them but no real damage. I got some red mithrax, cousin of the emeralds, with live rock I put in the tank. They have picked at my yellow polyps and were promptly removed to the refugium. I still have some reds in the tank. I monitor all their behavior but for the most part they are OK. They do get big though and from all the mixed reviews I have read, I watch to make sure they are not doing any damage.

 

[beerbaron]

so would you guys say that they are usually free roaming during the day to the point that i would be able to pull them out? or do they do like my rock crab which never comes out of the rock, even at night?
BB

 

[Diatomic Bomb]

I had a bubble algae problem in my tank and bought a couple of emeralds several months ago. I have never once seen them eating bubble algae, yet interestingly enough I no longer have any bubble algae in my tank. It took a month or so for the algae to finally be gone. They're almost constantly picking at the rocks even when there doesn't seem to be anything there to pick at. I think they're eating the algae just as it starts to grow on the rocks, before it's even big enough to see, which is why I never saw them actually eating it.

They don't cause any problems with any of my corals or fish. They're almost always in sight, are often walking slowly across the sand, and are fairly brave (meaning they don't skitter away when I approach them) so they'd be really easy to take out if I needed to.

Here's a pic of one of mine shaking his fist at my pygmy angel.

[/img]

 

[ReefRian]

For those of you who do not think emerals work, and for those of us that cannot remove all the rocks with bubble algae to scrub them, what do you suggest we do? The only way I know how to remove them for me is to pick them off with my fingernail. If the algae is small enough and my nails long enough, then I have no problem removing them. Occasionally I will have one break on me, but those are normally the ones that are bigger and fully imbedded in the rock.

Rian

 

[Will C1]

basically if you want to get one go ahead and get one you can allways remove it later even if you have to remove all the rock or wait a week for him to get comfortable with the tank and start moving around more freely. you can get it out if need be, but what if it takes care of youre problems and is a great addition to your reef? then you dont have to worry about it. :lol:

 

[Anonymous]

Ok.........I changed my mind....my next critter is goin to be an Emerald Crab.

 

[Chris Witort]

That's okay, maybe you brained your damage.

 

[beerbaron]

Ok.........I changed my mind....my next critter is goin to be an Emerald Crab.

boy your easily persuaded(sp). well i got one last night, ill see how it goes and if it starts working and nothings missing, ill get another if need be.

thanks for convincing me everybody
BB

 

[MandarinFish]

"Listen, rummy, I'm gonna say it plain and simple. Where'd you pinch the hooch? Is some blind tiger jerking suds on the side? " - Rex Banner
---------------------------------------------------------------------------------

Its been 8 months Beer Baron - do we have to send Rex Banner to catch you and beat a confession out of you? What is the result?

You're not the only one with valonia problems and mithrax/emerald crab concerns and considerations, you selfish bastard.

How has it worked?

Spill the beans.

:wink:

 

[mooner]

I have one and he has been very helpful. I have seen him eat bubble algae many times. So far he has been a good boy but he is getting quite large now so I watch him.

I say try a small one and watch him close. If it works out keep him if not take him back to your LFS.

 

[hillbilly]

I hate crabs of anykind in a reef! Even the hermit will kill your snails
to take the shell!

 

[Anonymous]

I wont ever have one in a reef of mine again. I tried it twice and they munched xenia and other softies. They were hard to catch, and the valonia seemed to grow anyway.

I suggest a pair of long tweezers or hemostats to remove the bubbles from the rock.

 

[Anonymous]

Another option is to suck the bubbles out and into a bucket with airline tubing. My emeralds don't touch valonia and so I vacuum the few that show up every couple of months.

 

[MandarinFish]

The weird thing is some people have great luck and some do not - this leads me to believe the idea that there are different species being sold as mithrax/emerald crabs.

I hate crabs of anykind in a reef! Even the hermit will kill your snails to take the shell!

I have the same concerns. Crabs are, by nature, opportunistic more than other orders of animals.

I have had a lot of snails that were wiped out in a tank collapse, so I have numerous old shells from nassarius, turbos, and margaritas that are spare.

My left-hand hermits have been able to scavenge their choice of shells without resorting to killing a snail within. Not that they wouldn't, but they don't have to. I imagine this helps keep my snail mortality down.

 

[Anonymous]

Any crab in your tank is a risk. They are all oppurtunistic feeders, and if the easy food is gone, the will go to the next easiest. Crabs are always a risk.

 

[cdeakle]

They are easy to catch!

Just get a chopstick and put a piece of sheet algae on it. Place the tip of the chopstick close to the emeralds and they will go nuts and go for the algae. My emeralds always grab onto the chopstick and I can simply pull them out of the tank.

Either that or I wave some algae in front of them and make them chase it to the top of the highest rock in the tank and simply scoop em up.

I had a sally lightfoot and that little iatch took an hour and a half to catch! Had to get her out because she would go after my smaller fish and nip at them.

Emeralds are cool, wouldn't ever reccomend getting a sally lightfoot though!!

 

[Anonymous]

One last pipe in...I have an emerald...and he is awesome...Very, Very peaceful...and it is a very good cleaner of algae...



8)

 

[beerbaron]

here i am, been away for some time, the emerald is basically not there. i never see him,,well rarely. he doesnt eat anything he isnt supposed to, that ive noticed, the bubble algae went away, but i think that was due to water conditions. now onto my new problem... flatworms...

 

[ReefRian]

You have to remember crabs are animals and have their own personalities, that's probably why some people have luck with them and others hate them with a vengence. Myself, I've never had any problems with my hermit, microhermits, or emerald. Just know that if you get hermits or crabs you need to make sure they have food and shells to move into, then they won't need to go on killing sprees.

Rian

 

[beerbaron]

yup what he said