What is irritating my zoanthids- Hydroids ??

[fvandijk]

I posted this in the zoanthid forum as well- but will post here in the hopes that a different group may read this forum.

Some background:
I am in the midst of setting up a new aquarium (Solana) to replace my 12 gallon nanocube. I had bought some live sand collected here in Florida. This had been in my aquarium for several weeks. Lots of pods, and a handful of Cerith snails and Nassarius snails that came with the sand were the only creatures in the aquarium until I added a small frag of some zoas I had a few days before I received my order from you. All parameters that I measured (nitrates, nitrites, ammonia) were undetectable. The "livestock" was doing fine.

I had placed an order for a few zoanthid frags from a reputable source. After the routine dip and inspection (which was negative) I decided that rather than putting the order I received from you in my regular quarantine tank (which has a crappy light and crappy circulation) or in my main tank (where my other zoanthids are that I was planning on moving to the Soland) I figured I would just put them in the new tank for a week or two until I am ready to add the live rock.

Initially everything looked great, but after a week or so I noticed that a few polyps were not opening up completely. Upon close inspection there were these little translucent "polyps" that seemed to be irritating the zoas- I am assuming these are hydroids, likely introduced with my live sand?? I am including a picture (best I could do) that I think shows them pretty well. It also show how the zoa is not opening up completely in response to the irritant- these are on three of my frags and in all cases, the adjacent zoa seems p*ssed off.
Does anyone have any better thoughts as to what these may be and how to best get rid of them? Is this something peppermint shrimp eat?

Thanks in advance,
Frans

 

[GoingPostal]

Look like possible hydroids to me, I would try scrubbing them off with a toothbrush or picking off with tweezers, they are pretty hard impossible to see out of the water however so it may take a couple tries to get them all off your zoos. I have some similar that are a pain in the butt, they seem to go in waves though, a bunch appeared out of nowhere and now most are gone.

 

[fvandijk]

Thanks going postal. That's exactly what I did last night- and as you say they were impossible to see out of the water. Someone in the zoanthid forum had suggested covering the spots where they were with superglue, but this included the base of the polyps, so I decided against that for now. Will keep everyone updated.