Emerald crab...friend or foe to the reef?

[Chaloupa]

I have a 65g tall hex reef with assorted mushrooms and a couple of corals....I have a mandarin, kole tang, pygmy angel, maroon clown, yellow watchman and bi color blenny.....(yes I know a lot of fish but I have a good skimmer and a good maintenance program so please no concern with my fish) I do have a bubble algae problem and have heard that they are good with dealing with it....is this true or are they more trouble than they warrant? Oh and I have a coral banded shrimp...your help with my question is MUCHLY appreciated!

[Blown 346]

They are supposed to be good with bubble algae but most of them dont even care about. They wont hurt anything in the tank, they will pick at algae.

[Ti]

They MIGHT pick at corals.
I've heard of it happening.
Mine used to scrape my coraline off the rocks faster than the coraline grew back.

[Chaloupa]

What would you all suggest for dealing with the dreaded bubble algae? I am just dealing with a nasty case of hair algae and have bubble on top of that....is my best bet to just go ahead with using Phosban and a reactor?

[TheBimbo]

Do not break open the algae in your tank, it will become worse as you're releasing the spores into your system and it will spread like crazy... I would remove your rock and pick them off, scrub them off, rinse and rinse and then rinse them some more with RO water... Emeralds will eat at it, but I'd try the remove and scrub method tooo... We battled HA, it destroyed our tank, it's just now healthy again... Lost alot of things b/f of the bad water, we didn't use RO water from the beginning, boy did we make a mistake...


TheBimbo:rollface:

[LTJGAlex]

I have to disagree with them not hurting anything. Very much disagree.

I put one in my 5g and immediately it began snapping ravenously at my clownfish. Then it got tired of that and proceeded to climb my feather dusters and start to rip their tubes apart and eat them. He was quickly removed and returned.

However, I haven't heard any other horror stories. Just be careful. I think the trick is to buy them small.

[my2girls]

Like thebimbo said, manual removal of BA sometimes is necessary. If you can't take the rock out, you can pick the algae off with something sharp and siphon it out at the same time. Try not to pop the bubbles. FWIW, I have never had and problems with emerald crabs.

[Madoktopus]

They Will Stab you in the back. they start of nice and small and harmless and then in a few moults time they are huge destructive aggresive and want to be hand fed nori or they will tear apart your favourite coral.

[brad23]

What about Salleys?

[LTJGAlex]

Even worse. At least mithrax are "often" said to be safe when small. Sally lightfoots are simply bad for reefs. First, they don't really eat all that much detritus, they mostly eat living things. They're known to catch and eat fish. Plus they hide all the time, you'll never see them.

Why buy a crab that will hide constantly and kill your friends when it can. :-(

[TheBimbo]

We had an arrow crab for a long time... It got sooo big, it was really neat to watch and I kept it well fed, but it eventually went back to the store...


TheBimbo :)

[LTJGAlex]

Yes, arrows are the single worst crab out of the usually-sold LFS crabs. I was convinced to buy one for my 5g nano by one of our more money-hungry LFS and it was immediately evil.

I bought him his own 1g where he speared and ate every damsel I tried to put in, killed all the pods he could, and harrassed a flame scallop. He molted once and doubled in size, he became enormous. He died before he could molt again, I think just from being moved to several different tanks a few times.

I'm really into inverts, that's why I know about these crabs. I've tried them all. Here are my findings so far:

Bad:
Mithrax (when big)
Sally lightfoot
Arrow
Sponge decorator
Blue legs (they grow and kill snails)

Good:
Porcelain anemone
Porcelain
Fiddler/red

On the fence about spider decorators. I have one in my 12g and he has never attempted to hurt any fish or inverts, but he does lumber around and loves to climb everything, so he's often walking through various corals and making them close up. He hasn't decorated at all either.

[brad23]

I know 2 guys who have sallys that are quite big and have neverr had a problem with them in a 75g reef and a 90g reef. There very active and always moving around.

[Dolfan0925]

Never had any problems with emerald crabs, I have about 5 or 6 in my 55g. I have no idea how many blue legs i have in my tank. I have a friend who has a 15g reef with lots of coral, two clowns, and the biggest sally lightfoot I've ever seen. I've heard bad things from people about sally's, but never really from someone who had them personally.

[techigirl78]

I'd also give thumbs up to the porcelains. Most trustworthy crab I have ever owned. It doesn't harass anything and is awesome. But, they don't clean up bubble algae.

I had emerals and never trusted them. As others have said, manual removal is usually the easiest way to get rid of bubble algae. Also, phosphate removers seemed to help me in the past.

[ihavfishues]

I read in a thread yesterday where one lady "siphoned" out the bubble algae... In the opinion of those replying to this thread, would any siphon/vaccum work?

Sorry if this seems to be a silly question, but I'm just learning about all this... :reading:

Thanks!

[Dolfan0925]

If you have a crazy outbreak of bubble algae maybe, but if you've just got a small infestation I would rather go with emerald crabs. I like them in the tank anyway, they're a nice addition.

[MiddletonMark]

I've had Emeralds for 2+ years, no significant problems at all.

Even with manual removal, I couldn't have defeated my bubble algae without them.

[Trekkie]

Mine's been fine, I've had two for over a year, they haven't gotten that big and just wander around scraping algae off the rocks.

[anabolic_1]

Just adding my 2cents. As said before blue legged hermits are muderers, they constantly kill my snails for their shells. I have had a problem in the past with BA and I added 3 emeralds 3 years ago and all BA is gone, but they seem only to come out at night. (same with peppermint shrimp, they ate all the aptasia anemones but you never see them) So far I have pulled out of my LR 3 very ugly (IMHO) red crabs which went tinto the QT tank, now they are huge and one looks like godzilla. I think all crabs are hit or miss, you can have one that will never touch anything and others that will think its a sunday brunch. Try the emerald for the BA if it becomes a problem, take it back to LFS and get a diff one. My current problem is hair algae, I have a sea hare now and I will see if he does a good job, I will post on his/its progress or lack thereof, BTW his name is Doodle, for obvious reasons.
GL
Mike.

[dhnguyen]

Actually to be on the safe side, ALL crabs should be avoided in a reef setup. All crabs are opportunistic omnivores meaning they can and will eat everything.

D.

[skippy2]

I have a little bit of bubble algae so I got an emarld crab. I caught him literally swinging on my kenya tree. Now I can't catch him.

[TheBimbo]

Originally posted by skippy2
I have a little bit of bubble algae so I got an emarld crab. I caught him literally swinging on my kenya tree. Now I can't catch him.


That's not good thing skippy :( ... On the bright side you can now call him Tarzan :) j/k...


TheBimbo:rollface:

[skippy2]

HAHA!!! Actually, Christy now I do.

[BriSape23]

Since I have had one in my tank for 3 months now...thought I would add something to this thread.

I had also heard that Emeralds can be predatory...but just like any crab they are opportunistic feeders. But I seem to have plenty for mine to pick off the rocks. I had a bubble algae problem as well and is the reason I got an Emerald crab. Took about a month...but then she started attacking it and now, no more bubble algae. :-)

I have not seen her pick at any corals. But there is pleny of other items to keep her busy. If you have a good LFS, I would recommend getting one. However make sure they give you a female. The females are less aggressive and also will not get as big as the males. The females will have a flap on the underside where they carry the eggs. Males will not. Your LFS should know the difference.

[LTJGAlex]

LOL, to make light of all this a little...

I should have related my emerald removal story. On the day that I put him in there and saw his evil behavior, I reached my hand in to pull him out. Well, he clung to a rock and it took me 30 angered minutes to pry him off, with a lot of grunting, complaining and curses. Unfortunately, I was on a second date with a girl with whom I seemed to be doing very, very well. After that day she broke up over the phone because she said I'm too impatient and frustrated!!!

Oh well. Score: Hobby: 1 / sex life: 0. :)

[TheBimbo]

:eek:



TheBimbo:lol:

[Madoktopus]

my emerald was perfect at first small and nice. then he was huge ond day (claws bigger than him nearly!) and jus sat on a toadstool so it wouldnt come out and picked at various soft coral polyps. i had o hand feed him nori to stop this behaviour but that didnt stop him from attacking the fish. took 2 hours to catch him which led to a rockslide and a complete re aquascape. "hulk" promtly went back to my lfs where they gave me £6 for him. good riddance!

[TheBimbo]

Originally posted by Madoktopus
my emerald was perfect at first small and nice. then he was huge ond day (claws bigger than him nearly!) and jus sat on a toadstool so it wouldnt come out and picked at various soft coral polyps. i had o hand feed him nori to stop this behaviour but that didnt stop him from attacking the fish. took 2 hours to catch him which led to a rockslide and a complete re aquascape. "hulk" promtly went back to my lfs where they gave me £6 for him. good riddance!


Atleast they took him back... I know we used to take fish, and such back all of the time... Has anyone seen the red ones??? We've had atleast 2 of those b/f along with the green ones...


TheBimbo:rollface:

[LTJGAlex]

Yes, they are identical in terms of behavior and temperment.

[MCary]

My Coral Beauty seeks out my Emeralds and lets them clean her just like a cleaner shrimp.

[ACBlinky]

Originally posted by BriSape23
...If you have a good LFS, I would recommend getting one. However make sure they give you a female. The females are less aggressive and also will not get as big as the males. The females will have a flap on the underside where they carry the eggs. Males will not. Your LFS should know the difference.
Just wanted to second this - I had a (pink) male who matured very quickly and started showing too much of an interest in my corals and taking swipes at passing fish. Now when customers come into the LFS where I work weekends looking for emeralds to add to their reef, I catch them a female. Those with FOWLR tanks get males - there may be no basis to my theory that the girls are more reef safe, but I figure it can't hurt.
Here's an article (http://www.saltcorner.com/sections/guest/marineworld/Friend%20or%20Foe%208.pdf) I found on crabs that shows a nice picture of the underside of a female teddybear crab - to me, emerald crabs look like they have a 'six pack'; males have a point dividing the two halves, females don't.

[Thorndunes]

I put 2 in my tank with my janitor crew. After 3 days, 1 was dead in the morning. Don't know for sure but I think the other one is guilty.
The other one lasted a few monthes then died himself, could be they were doomed from the start. I bought them mail order and I lost a good portion of the order.

They NEVER bothered anything though as far as I saw.

[R33f3r]

I have owned several in the past, luckily they never ate any coral or harmed any fish, but they did eat tons of coralline and green hair algae. Never touched the valonia. All of them died within a year.

[Amy83820]

I've had my emerald crab for about 7 months and he seems to be doing fine.... no coral casualties!