is there really a reef-safe crab?

The friendliest place on the web for anyone with an interest in aquariums or fish keeping!
If you have answers, please help by responding to the unanswered posts.


Aquarium Advice Activist
Jan 11, 2004
Found this:

claiming that Emerald crabs and sally lightfoot crabs are reef-safe. I've recently evicted a red stone crab when I put my first corals in (well, it _looks_ like an emerald except it's red), and we kind of miss the little guy (lots of personality). Will either of these crabs (in the link) leave my xenia and zoos alone?

Sanity check, please, and thanks.
I had 6 of those red mithrax crabs. They tore up a yellow polyp colony I had. Just mowed it down. So sad. I tore every single one of those out of my tank (the last of which is still sitting in my QT tank, the others had been put in witness protection)! I DO have 5 emerald crabs and they haven't touched a single coral polyp in my entire tank. They're fun to watch and are eager at feeding time, often running into the sand to grab a morsel. I can't speak for the Sally Lightfoot because I don't have one of those but the Emeralds are a peaceful inhabitant in my reef.
this is still a topic of debate. From psonal experience, I have found my reef hermits, porcelins and emerald crabs to be reef safe. I have never witness any of them bothering my corals and I spend a lot of time looking at and inspecting my tanks.
The only type of crabs I have found to be reef safe are

Bang did you have an Emerald go after your corals? Please elaborate!
I had a black stone ??? crab that i just got rid of. One day I had yellow poylps, and pulsating xenia, the next day nada!! :evil:
i have had an arrow crab and an emrald crab with polyps and zoos with no problem along with blue leged hermits. The only thing about the arrow is it did eat my bristle worms, but never touched the feather duster (although i have heard they do from time to time eat them)
Phyl said:
Bang did you have an Emerald go after your corals? Please elaborate!

I suppose it depends on your definition of "Reef Safe". I've had large ones eat Peppermint Shrimp and attempt to catch fish. I've never seen one harm a coral though.
I've had large ones eat Peppermint Shrimp

Wow. I can't even imagine... but then mine are still around the body size of a nickle.

Very cool -- thanks Everyone!

SOoooOOOoooOO? What have you decided? Do tell!
Oh, sorry, Phyl. Not sure yet -- need to talk it over at home. The red mythrax is in QT right now. The kids really like him (active with lots of personality), but I really want some basic soft corals to brighten the tank up a bit. Sounds like the emeralds will fit the bill all around. I'll probably set up the red dude in a small nano (1 gal) for either the office at work or somewhere else in the house. The only alternative is to put the red guy back in the main tank (keeping it FOWLR), and start a proper nano (eg, JBJ 12 gal) for reefing -- but that's more than I want or have time for.

Thanks again for everyone's help!
Top Bottom