Zoas closed up

[Grant]

I've noticed that for the past week or so, one (out of the three) zoa colonies in my tank have remained mostly closed up. Every now and then a few polyps will open, but for the most part they're closed up as if I was turning the lights on or off, changing the water, or something else that would "bother" them. The strange thing is that the other two colonies are fine, and are right next to (and slightly intermingled with) them:

[attachment=0]zoas.jpg[/attachment]

The closed up are some watermelon variation. Next to them are RDE and some Purple Death. Both of them are fine.

Any idea what would make just one type of zoa close while the others are fine? No new additions to the tank in a long time (since I'm out of room!). I did a check for ammonia, nitrites, and nitrates. All were 0. Salinity was slightly above 1.026 (less than 1.027 though), which I'll take care of with a water change today hopefully. I'll do phosphate, calcium, PH, and the rest of the tests this evening after work, just in case. But everything else in the tank seems happy and healthy.

 

[Ben]

Sometimes they just close up. Can try doing a ph and temp identical freshwater dip with 5 parts fw to 1 part hydrogen peroxide for 5 minutes and that should kill any possible predator that might be disturbing them.

 

[khoff]

Any change in lighting or flow? That may send them into a tizzy. Have they been "happy" in that location for a while, and then started closing? I wouldn't use other colonies as an indicator for much other than water quality... each zoa will have a different "personality" and spot that it likes.

It may also have it's own special predator that likes to only munch on one specific type of zoa. Any signs of nudibranchs or asterina stars on them?

 

[Zoa_joc]

@khoff wrote:

+1,000,000

 

[Grant]

@khoff wrote:

No changes in lighting or flow for almost a year now. That's the spot they started in, when they were just a few polyps on a frag plug (the plug is actually still underneath them). The only change has been the tank temperature has gone up slightly since the weather got warmer (from 78-79 up to 80-81). But those temps were the same last year and they didn't seem to be bothered.

I do have an asterina or two, but the last time I saw them they were in the back chamber with the heater. I haven't seem them in the display in months.

 

[khoff]

You might check with a flashlight, or even turn the blues back on, an hour or two after lights out just to be sure nothing is snacking on them...

I would recommend some sort of dip just as a precaution. I use CoralRX as a general dip, FWE for nudis, peroxide if they have algae growing on them, or fish flex if there's a sign of a bacterial infection. I'll often mix CoralRX and fish flex with no ill effect, however I couldn't say if one somehow neutralizes the other.