Originally Posted by
Sir Patrick
Zoas not opening- there are many reasons for this to happen. I will go through a few-
Aclimation- zoas can be very sensitive to new tanks/parameters/flow/lights. Until they are aclimated, when newly added to a tank, they can at times take a very long time to open.
Predators/irritators- zoas will close when being bothered. If your zoas close up, and dont open, take a really close look at the cosed polyps for nudis, flatworms, asterinas, spiders, bristol worms, algea, vermitid snails, and fungus. Also includes hermits and snails that have traveled through the polyps. Pretty much anything that could be touching the polyp, or brushing against it to make it close.
PH and alk and temperature swings- All of these are known to bother zoas and somtimes close them up.
Fungus, bacterias and zoa pox- Look for any kind of sponge or paste material in your polyps. Also watch for white bumps/lesions on the stalks of your polyps.
Light shock- it can close up, and also bleach, polyps if time isnt taken to aclimate them to new, higher output lighting.
Nipping/perching- Some fish (along with many considered reef safe) might develop a tendancy to nip/eat polyps. Some of these include- Tangs, rabit fish, butterflys, and angels, and also sally lightfoot and emerald crabs. All have been known to develop a taste for polyps. Not saying they will, but can. Others have the tendancy to perch on polyps, causing them to close up. Some of these include- Blennies, dragonettes, and hawkfish.
Stray voltage- This will irritate zoas into closing up.
Any of these sound right?