So i decided to pick up a emerald crab about 2 weeks ago. Last night I was looking in the tank when lights were out and noticed the crab hangin around my palm glove polyps...not sure if he was eating them or picking at the polyps directly but he was shifting them with his claws. I purchased it from the LFS and was told they are good for clean up and are reef "safe" but after reading from some sources that they have been known to eat corals, ive become worried that i might start losing corals. I dont really have an abundance of coral yet since the tank is new, but i will definitely know if he eats one of the polyps. The crab is about 3/4-1" and im wondering if i should take him back or leave him in the tank. Any suggestions?
Emerald Crabs safe?
- Thread starter k2bordr03
- Start date
BoomerD
Well-Known Member
Depends on your definition of safe. The last one I had tried to dismantle one of my serpent stars, so the crab got banished to the sump. Crabs, even emeralds, tend to be very opportunistic feeders. I had a Sally Lightfoot crab in my 90 that I watched catch and eat a baby Bangaii cardinal...that was it for that crab too...After that, I got rid of all my hermits except the scarlets...even the blue legs tend to be pretty opportunistic, and are well known for killing snails to take their shells...
bummer 
I'm new to the sw hobby and trying to get my bearings still. I just put 6 corals in the tank and really would hate to lose them to a $6 crab. Its not like i have any missing that i have noticed, but I'm not so sure it was a smart purchase after I read more on emerald crabs.
I'm new to the sw hobby and trying to get my bearings still. I just put 6 corals in the tank and really would hate to lose them to a $6 crab. Its not like i have any missing that i have noticed, but I'm not so sure it was a smart purchase after I read more on emerald crabs.
framerguy
Well-Known Member
IME when emeralds a smaller they are good algae eaters. As they gain age and size they tend to shift to a more meaty diet..like fish and coral. Use them when they are small and ditch them when they get large. If you notice them pulling polyps it's time to get rid of them.
Witfull
Well-Known Member
^you musta read my manifesto~
http://www.reefsanctuary.com/forums.../8010-crab-manifesto.html?highlight=manifesto
http://www.reefsanctuary.com/forums.../8010-crab-manifesto.html?highlight=manifesto
framerguy
Well-Known Member
Hey, that's pretty cool. No I hadn't read that but it's dead on with what's been happening in my tank. I bought some little guys, they ate algae just fine. Then they got bigger and one day, whammmmo, they're eating clove polyps as fast as they can. In the fuge they go. Got some more little ones, eatin' algae as we type! I've got the fuge ready and waitin'...
SaltwaterGeek
Member
I once had an emerald crab that must had been fed gun powder at the wholesalers!..LOL.
After a week of getting his barrings, he first started bullying some coral... Then went on to shred some Nassarius snails, and then gutted a small horseshoe crab I had. Needless to say I won't have one of them again.
Chris
After a week of getting his barrings, he first started bullying some coral... Then went on to shred some Nassarius snails, and then gutted a small horseshoe crab I had. Needless to say I won't have one of them again.
Chris
Tru2nr
Well-Known Member
mine are gettin big and do a great job eating algae but i have a feeling they're not gonna stay that way for long i found one who was eatn' some algae off of my star polyps but he looked up to something considering everytime i looked close to the tank at him he ran and hid which is new for him so i think he knows hes doin somethin wrong
BEELZEBOB
Well-Known Member
most risks pertaining to mynthrax crabs ive heard is from them attacking like snails stars conches and other mobile verts.
i think they're given a "reefsafe" title most likely because they are not in the genius of crabies the feed on corals.
but you never know.
especially if some uber reefer like WIT says they're nasty
i think they're given a "reefsafe" title most likely because they are not in the genius of crabies the feed on corals.
but you never know.
especially if some uber reefer like WIT says they're nasty
lauralarue2
New Member
I recently added an emerald crab to one of my tanks too. They are indeed good for eating all kinds of algaes... but I have noticed it picking on my precious corals. In addition, it moves around some of my lighter pieces of live rock too. I wake up in the morning to find small white scratches all over my newly reconfigured nano-tank. I love the beauty of my coralline algaes and corals to much to sacrafice them to a nocturnal crab. I have found the best way to catch or "get rid" of them is to net them during the night when the lights are out (this can be made easier if you have blue light spectrum which adds the "moonlight" effect). Best of luck crabbing!
sandygarden
New Member
Added an emerald crab, arrow crab, and staghorn crab. Within 48hrs the emerald was observed nibbling on a green clove, xenia, and strongly suspected of nibbling on and knocking off kryptonite green coral, and seen on turbanaria-whatever he was doing there. However much good they do I'm not sure it's worth the worry and constant detailed observation for damage. Like the ump says "you're outa there!!!!!"
