Unknown threat to zoas

Top Shelf Aquatics


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Mar 20, 2020
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I have an emerald crab in my sump because I watched him pick a polyp off of a clove polyp and eat. Mine never ate zoas, that I know of, but after seeing how quick he ate the clove polyp I wouldn't be surprised if they could clean off a frag plug in a night. If you have forceps emerald crabs are easy to grab if you ever see them out in the open, or at least mine was. I chased it all over the tank with my hands and then I picked it right up with forceps.


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Aug 6, 2020
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Something is happening to my zoas. At first I noticed some recession on the colony of fire and ice zoas I have on a rock that I'm using to build a zoa garden. Then I had a 1 inch frag plug totally covered in the same fire and ice zoas that overnight was halfway completely cleaned off. I asked the owners of 2 different LFSs near me about it and neither of them could think of anything specific. These issues did start occuring after I added an emerald crab, but they said an emerald crab likely wouldn't have eaten them that quickly, especially just one. Now here's the kicker, I just got a small frag of rasta zoas a couple days ago and now after coming home from work there's nothing but a tiny bit of flesh left of them. It was only 2 polyps but still VERY frustrating. Any ideas of things to check/look for? I havent noticed any sort of pyramid snails, that's what one owner told me to check for. All these colonies and frags are either on the sand bed or close to it so I asked if my current spaghetti worm infestation could have caused it and they said not like it's happening.
I've had emerald crabs eat coral and my starfish i had cleaned plugs of mushrooms in one night.


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Dec 19, 2019
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I have a blue hippo tank that has been in my tank for 1 year with all types of coral. Then all of a sudden he just started eating all my zoas and once I removed all remaining zoas he started to go after the polyps on my acros. So keep an eye on your tang. Also I have seen videos of I thing there big Medusa worms eating zoa polyps also.
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