Why are my zoanthids wilting?

[trilinearmipmap]

Some brown zoanthids came in on my live rock a few months ago.

They did well at first and propagated nicely.

For the past week they look sickly, the tentacles are thin and wilted, the body of the zoanthids look flaccid.

My parameters all test out OK: temp 80, pH 8.2 to 8.3, zero ammonia/nitrites/nitrates. The rest of the tank inhabitants are healthy (assorted soft and hard corals, crabs, 2 clownfish).

I have narrowed down the possibilities:

1. Too much light -- they are high up on the rock under fairly intense T5 lighting.

2. Lack of nutrients -- the tanks is fed sparingly so far due to low fish load.

3. Depletion of trace elements -- no water has been done yet, I had really ought to do one.

4. Allelopathy -- I don't know is this concept is for real or not.

Any advice on this would be helpful, thanks.

[Invigor]

I'd try a good water change, see what happens -- Something like 25-50%

Maybe lower your temp if you can a few degrees.

[DEAD_BY_DAWN]

lack of water flow over them ? mine look 100% better when theres a nice current of water blowing over them .

[Quinn]

Allelopathy in aquaria is real, although I'm not sure it's called that in this context. I don't think it's likely, but what corals do you have nearby?

[trilinearmipmap]

Flow is moderate, they are 6" laterally displaced from the output of a Tunze stream.

Other corals and things in the tank include: a few different kinds of zoanthids, bubble coral, colt coral, trumpet coral, blue mushrooms, green hairy mushrooms, montipora digitata frags, clove polyps, and unknown yellow polyps. But nothing is too close to the zoanthids except the montipora, and it was introduced after the melting of the zoanthids started.

[Beverly]

I was having a few of my zoo colonies not opening fully for the last couple of days. Today was turkey basting day so I can siphon out crud from my BB tanks on water change day tomorrow. Lightly basting the zoos opened them up nicely. Don't think I have a water flow problem as there is moderate movement throughout the tank. Or at least, that's how it appears to me.

[Bob I]

A little bit of advice from a person who grows a lot of zoanthids. those brown polyps may be something you don't want in your tank at all. I have some, and I have found they grow where you don't want them. I have tried to scrub my LR to no avail. I am hoping the introduction of a Pearlscale Butterfly, which someone does not want because it attacks polyps will help me get rid of them.

[trilinearmipmap]

Thanks for the advice.

I don't even like the brown zoanthids because they are ugly. I was just concerned to make sure there is nothing wrong with my tank causing them to wilt. Anyways it looks like they are dying off whatever the cause.