eating zoas

I got a new piece of live rock with a couple of colonies of zoas the other day. Now they are all gone. Nothing seems to be bothering my other zoas. These were all "young", small, and I placed them on the bottom of the tank, but there were a couple of others close by that didn't seem to get hit. What could be doing this. I have reef safe fish, so shouldn't be them. I do have a couple of sand eating cucumbers (brown with white spots) that are supposed to be active at night. I never see them moving during the day. I have a potter angel, coral beauty angel, green coris wrasse, tri color wrasse, blue tang, spotted rabbitfish, two clowns, a few firefish, lawnmower blenny, and mandarin dragonette. Any ideas?

 

that colony had zoa eating nudibranchs..... unfortunatly they will probably go after your other zoas now

 

do u have any urchins?

 

My first guess would be zoa eating nudis.. I just found out i have some and going to treat the tank with "Flatworm exit".. seems like it's the only thing that really works

 

Rabbit fish, Coral beauty, possibly the potters but the other two more likely, all three of them are know to nip at corals and clams and almost every thing you can find on them say "reef compatible with caution" . Nudis would be a good answer but not that fast, they would take more that a couple of days to eat a bunch of zoo's. I also say this becasue even if they eat them there is still some evidence where if its was one of the fish the Zoo's would be gone.

 

I do have a tuxedo urchin. I thought the green coris wrasse was good at getting rid of little pests that come in on live rock.