Sally Lightfoot Crabs?

[yeldarbj]

What's the general concensus on the sally lightfoot crabs? Reef-safe with all types of corals - polyps, LPS, SPS? Good algae grazers? Or pests?

I had to get rid of my Foxface because he was starting to nip at some corals and taking apart some clove polyps & pipe organ polyps. Now I realize what a good job he was doing at keeping algae in check on my rock.

So now I'm thinking about adding some green mithrax and sally lightfoot crabs to help control little pockets of algae. I've had a green mithrax that did a good job, but it's been MIA for a couple of months. A couple of Porcelain crabs went MIA too.

I've got plenty of snails and scarlet hermits, but they aren't doing much on the algae.

[Dubbin1]

They are considered to not be reef safe.

[Sk8r]

Go back, it's a trap.

The sallys are wonderful to watch when young, but if you're unlucky and they thrive, they get the size of a dinner plate and, I'm told, develop a taste for fish. We used to get them all the time, but tanks weren't that good back in dino days, and they wouldn't last more than a year or so. Now, with better tanks and better understanding of these creatures, the chance one would live long enough to be a problem is fairly good.

What types of algae are you having? There are some fairly good ways to reduce this without using critters, and some critters that are pretty good generalists.
1. if you have algae, you have a glut of phosphate bound up in it: it won't test as present, but any time something that eats it poo's it's going back into the tank to feed more algae. To get phosphate OUT of the loop, you need:
a. a good skimmer
b. dripping kalk can help it precip out, esp if you have the kalk drip aimed right at the intake of the skimmer. [kalk is said to take out: strontium, magnesium, and phosphate. Two you put back: phosphate you are glad to have gone.]
c. a refugium in competition for nutrients---not a magic cure, but a big refugium can help, plus add oxygenation and generally help water quality.
d. phosban, etc., an iron compound that sops up loose phosphate when it's in the 'free' state. As aforesaid, hard to get it liberated from the algae so something like phosban can grab it.
e. RO/DI: if you aren't using ro/di or if your cylinder's getting depleted, you're probably inputting something that's feeding the algae.

THings that eat algae: the lawnmower blenny eats anything that sticks to rocks.
Caulerpa-eaters: rabbit, tripneustes gratilla urchin, and one variety of sea hare [poisons tank if it dies: I prefer the algae], or a purple tang --- this is individual with them: test fish before buying.
If it's halimeda or bryopsis, there are ways, but I don't know them.