emerald crab vs. coraline algae

[beginnermatt]

Since adding the crab to my tank the coraline algae has been picked off the LR. Is this a bad thing? It visually makes the rock look bad. Thanks for any thoughts.

 

[footbag]

I don't think that the emerald crab ate your algae. Has the coraline rock been recently added? Maybe it's bleaching. My emeralds eat algae, but not the coraline or else they wouldn't be in there.

 

[saltymom]

I have two emeralds in my tank..they pick it at the coraline, but Ive only noticed it spreading..not disappearing. Its even on the back glass alittle bit now, in a few spots. My tank has been set up since 11/03

 

[new_noob]

actually your emeralds are helping you, when they walk across your rocks the brisstles on thier legs scratch your coralline causing the sporse to come loose and get released, and when they pick it off, they dont mean to, they are just eating the algae, but agien thats helping the coralline spread.

 

[buzz]

I'm not so sure the hairs on their legs are removing coralline. I had a few emeralds, and could sit and watch them strip the coralline from the rocks. They use their claws, and feast on it. It isn't necessarily a bad thing, but I hated the way my rocks looked. What did I do? I no longer have emerald crabs...

 

[new_noob]

the legs aren't "removing" it they are just helping release the sporse, like if you brush your rocks with a hard bristle tooth brush, that releases the sporse and spreads the coraline "seeds" so to say, dont know what elge to call it...

 

[thomas712]

Take a good look at those claws. They were meant to do exactly what your talking about. I did have one in my 55 that practically stripped the live rock. This was years ago when I was not adding additives at all for calcium and alkalinity. Then I went to the B-ionic and the coralline came back. With my experience I saw that he would scrape the coralline and eat it but he was also spreading the spores around helping to regrow the coralline. I have never had another active coralline muncher as I did with him.
Thomas

 

[litmus]

I've noticed that both my hermits and my emeralds will pick at the coralline.
You might want to try target feeding them. Take a sheet of seaweed selects or nori and place it on the liverock. Use a small rock or some other method to hold it in place (otherwise it will blow around the tank). The crabs should find it.

 

[nm reef]

Emeralds may be guilty of picking at coraline algaes but the ones I keep have never caused extensive enough damage to convince me to remove them. They also will pick/munch many other types of algae(including young valonia) so in my opinion they more than earn their keep and if they munch a bit of coraline from time to time thats part of the package. Besides if there is a healthy coraline growth and the system is stable/mature I don't believe a few emeralds will severely reduce the growth/spread of coraline algaes. In my reef they'd have to have some seriously healthy appitites to reduce the growth/spread of coraline. But in all honesty the emeralds I've kept seem to prefer much more tender and readily available types of algae.:thinking:

 

[reefsoe]

Take note that there are a few ( MIthrax ) crab species
Check the joints on the arm where the elbows would be because ive seen NO coraline damage from my mithrax with the red elbows and remembered my mithrax without red joints peeling it off rocks...