Following on...
I transferred these to my frag tank a few months ago, it's a shallower tank and they shrunk down and the umbrella issue stopped... For a while at least.
Since then, in my highly unstable frag tank, I've seen them do it again, also my Krak gods, Tyree Orange Rainbow and a few other, as yet unnamed morphs, have also followed my rainbow blues by taking on an umbrella shape.
As I can not rest until I can figure out exactly what causes this I have vowed to myself to figure this out.
So far I have noticed the following circumstances where this "phenomenon" has reared its ugly head and IMO it's all down to negative lighting changes and clarity.
Chemicleaned tank, turned lighting intensity down by 15%, within a week low lying Zoa colonies displayed umbrella syndrome, all Zoas on racks at the side of the tank seemed mainly unaffected.
Had a Krak God arrive from a friend who had his high up under Radions, within a month I saw umbrella shape to the polyp but it still threw out babies and they were all fine and fragged fine and spread well also.
Removed UV lamp from system, few weeks later sunny D's showed umbrella shape.
Did a water change, to reduce light shock from low water height, I used a plastic storage box lid to shade the corals, umbrella syndrome appeared within a few hours and is in the process of, hopefully, recovery.
In this scenario I had to consider sudden extra lighting as I had to remove the plastic lid after the water change, although I still believe it was from removing the intensity suddenly.
Made a change to the lighting, turned the intensity up a little, saw some Zoas expelling zoox so turned back down. Umbrella effect noticeable on other Zoas shortly after.
I have also noticed another effect, but in this case it is positive and seems to remedy the situation, or at least it has for me.
I have a Hydrogen peroxide reactor, a söchting oxydator. I was using this to aid in marine velvet (all fish are now immune
). After I removed it from my frag tank a few weeks later some polyps started to take on the umbrella shape, I believe from me doing a water change during lights on and dropping and raising the water level. A while later I re installed the reactor and the umbrella syndrome reversed and they went back to normal within a day or so.
I am now starting to think the umbrella syndrome is caused by a oxygen defficiency from the polyps suddenly not receiving the light they were used to / or were trying to adjust too and this causes them to get 'stuck in motion'. I also believe this is why the h202 helps as it both improves clarity and makes additional O2 available to the polyp for it to be recieved directly. I agree this theory is Extremely anecdotal at this time though
In each of my circumstances there would have been a period where the lighting was increased at some point also so I can not entirely rule out it being from the additional lighting although I believe in each scenario the actual reason for the umbrella shape to occur is from the subsequent removal of intensity as IMO if it was just from the sudden increase the palys would just bleach and expel zoox, I believe palys are very good at doing this (one reason why they don't get Zoa pox). Also I see it mainly happening to palys, candy reds, rainbows etc but it's also happened to my tutty fruity Zoas, I would have expected these to bleach or melt if it were from the additional light scenario.
I'm still in the process of verifying this so please be cautious with h202 and your Zoas.
I would suggest not changing the lights settings or doing anything to interfere with the normal tank lighting during the day cycle, as this seems to have an almost instant negative effect.
I'll also note that in almost all cases that I've experienced myself with umbrella syndrome appearing, all Zoas affected would take on a stretched look until they either slowly shrunk and turned in to little white lumps, shrunk way down then regenerated, or just shrunk down a little and suddenly appeared "normal", the latter being what I've experienced with the peroxide.
