Emerald Mithrax... anybody else have issues? (pic)

[ReefEnabler]

Hello,

A few nights ago I spotted one of my Emerald Mithrax crabs perched inside my Millepora coral. Didn't really see him doing much. Here's a photo:

http://www.worstkind.com/aquarium/crabmilli.jpg

I posted the observation in my build thread (red house if you want to see), and some guessed it was probably just passing through, and that if it was picking the Mille, that it wouldn't likely cause harm.

The next day the crab was gone and the coral looked fine so I didn't think much of it.

So last night while feeding my LPS I noticed not one, but all three of my emerald crabs perched in the mille, and this time I could clearly see them picking at the polyps.

I didn't think they would actually gang up on a coral like that... I got worried and used my TomAquatics Aquatic Gardener (long plastic grabber tool) to capture two of the Emerald crabs and banished them to my refugium for now. The third crab dissapeared....



I know most people will say these are reef safe, and that they will eat algae if there is any. I do notice them eating plenty of algae; most of the day they feed on hair algae. I do have little bits of hair algae here and there, but its far from being a "hair algae problem". my tank is only a couple months old so its to be expected (water params great, 0 nitrates according to API).


I am just curious if others have had... trust issues with their Mithrax?

Also curious how big they get. I've had them about 3 weeks, and one of them has already grown considerably.

Thanks,
Ryan

[ScooterBlenny]

Occasionally I'll catch mine picking at a coral. They get "spanked" with the feeding tongs, and then go along their merry ways. They haven't really hurt anything, and I don't catch them doing it often, but they definitely can pick at corals.

[plateboy3293]

An emerald killed one of my plate corals a while back. Just kept picking at the tentacles.

[nattydread]

No corals yet, but they stripped off all the coraline.

[stlrams88]

took mine back yesterday because it was picking all the "fuzz" off my fuzzy shrooms. My buddy that lives down the hall had his pick at some pretty expensive zoas so it went back too.

[Don-Coraleone]

i usually catch mine picking at my zoos.

[Rae C.]

Mine was a good two inches before it croaked. It occasionally rested in my SPS and nibbled a bit, but never actually harmed it. i think there was some algae starting up in it's branches.

The crab did enjoy hunting down snails at feeding time and ripping them out of their shells. Especially after the algae was getting thin.

[Gwynhidwy]

All crabs are opportunistic as far as I know and in my opinion, not to be trusted. I think they are great fun to watch, but I don't have any crabs in any of my tanks for that reason.

[Capt_Cully]

I used to love them until I witnessed one tearing tentacles off of my prized "todd's torch" a highly sought after coral in our area due to it's ultra neon color.

Let's just say I don't have ANY mythrax in my system anymore.

[ReefEnabler]

thanks for all the input guys.

theres only 1 emerald left in my tank since I couldn't find him, but I think I'll just keep a close eye on my corals at night time to see what he does before putting him in the fuge too.

but I assume that the other two will do just fine in the fuge. theres plenty of cheato algae, which I think they will eat?

this is one benefit of a refugium, a place to put guys like this in time out until I can figure out if they are a threat :)

[Capt_Cully]

ha ha, my fuge has been used for various solitary confinements and "time outs" over the years.

[spleify]

Ryan I have a emerald that has made his home in a millie also. It kind of freaked me out at first and I actually tried for about a week to pull him out of the tank as I was concerned he has going to eat the coral. Been about 3 months now and he has done no damage and moves all over the coral. It does seem he irritates the area where is is at that particular time but has done no damage.

JME

HTH

Spleify

[TheORKINMan]

My emerald has always been a model citizen, he picks startup algae growth from around the rims of my LPS and picks algae off of the SPS, never seem him actually pick off a polyp

[rampantmarine]

<a href=showthread.php?s=&postid=13559862#post13559862 target=_blank>Originally posted</a> by out
The crab did enjoy hunting down snails at feeding time and ripping them out of their shells. Especially after the algae was getting thin.

Maybe that's why I have all the snail-less shells???:confused: