Do Emerald Crabs eat Xenia?

[rrasco]

Yesterday I noticed my Xenia was gone. It didn't slowly die and it didn't get knocked off, I can still see the base of it there, I think so anyways. I'm assuming my Emerald Crab ate it, or at least destroyed it. I have seen him pull at a zoa or two, but then he left it alone, I always presumed a case of mistaken identify as he was eating algae around them at the time. I saw my Xenia at least 2 days ago so it was something recently. The tank is starting to get slim on algae, so maybe he's looking for alternative food sources? Maybe it's time to start supplemental feeding for him.

Any idea what else could have happened?

[Cammed_02]

I have pulsing xenia and the crab has never touched any of it. Any other culprits you can think of?

[rrasco]

Not that I know of. There are two crabs, one emerald and one 'red' one that 'is just like the emerald but a different color', so I was told. Other than that, there is a blenny, pair of false percs, and that's it. The only hitch-hikers I've seen were bristleworms and a few astrea stars (I pull the stars when I see them).

[StevenSeas]

That is odd as far as the xenia goes. I would be very doubtful that a mithrax (either red or emerald) would eat xenia as it can put off some pretty nasty toxins. I would check your other water parameters as soon as you can. Don't want to ask a dumb question but are you sure that the xenia isn't just closed up all the way? If you do think something killed off your xenias I would replace your chemical filtrant (carbon, chemi pure, etc) and if you have a protein skimmer start skimming a little wetter than normal to prevent a buildup of toxins in the tank.

here is a little more info on that red crab of yours, (from sea life inc.)

Red Mithrax crabs, Mithrax ruber, are very close relatives to the green emerald crabs, Mithrax sculptus . The red mithrax crabs tend to be more of an offshore, reef dwelling crab, so I think they are actually more suited for a reef tank than the green crabs, which tend to be more of an inshore, non-reef dwelling crab. Both crabs will clean bubble algae, and hair algae, and both will clean other unwanted fleshy macro algae from your tank. You can mix them freely with the emerald crabs and they will get along fine. Maximum size is about 1 ½"" carapace width, and we prefer to ship them at about ½"" to ¾"".

[rrasco]

Thanks Steven. I guess it is possible it's closed up, maybe it will be open when I get home today. It sure looked like it was gone though. This tank has hit a rough patch though as it's approaching 1 year and I don't dose anything, I think it's beginning to kind of plateau. I'm trying to increase water changes to keep the nutrient levels up. I don't run chemical filtration. Also, my skimmer pump died a few weeks ago so this tank has been skimmerless and I have not been able to replace or fix it. I would put an emphasis on that, but I have a new tank that is *almost* ready to go with a lot better equipment and maintenance setup, so I'm really hoping to get everything moved over there before I take the 'next step' on my reef.