What the heck is wrong with my zoanthids!?!

fishwhisperatx

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I can not figure out what in the world is going on with my zoos. I have had them for 8 years with no issues. They have grown into colonies of hundreds. About 8 weeks ago 1 or 2 heads wouldn't open. It's slowly got worse. It went from some not open to a bunch curled up or not open all the way. And now they are looking terrible. Some of them look like they have cottage cheese on heads. Please see pictures.
I am not new to this it's actually my profession which is what is so frustrating about this. I have never run into this issue. I have already dipped them in iodine based reef dip and coral rx. There are no bugs no flat worms no spiders no nudibranchs and it's definitely not zoa pox. My parameters are perfect as always.

Kh 8.5
Cal 450
Nitrates 5
Phosphate.05
Magnesium 1350
Temp 78

17451089263945144711467796366249.jpg 17451089921992652130806395616013.jpg 17451090141891755663463575993363.jpg PXL_20250413_194954672.jpg
 

william Lutman

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I can not figure out what in the world is going on with my zoos. I have had them for 8 years with no issues. They have grown into colonies of hundreds. About 8 weeks ago 1 or 2 heads wouldn't open. It's slowly got worse. It went from some not open to a bunch curled up or not open all the way. And now they are looking terrible. Some of them look like they have cottage cheese on heads. Please see pictures.
I am not new to this it's actually my profession which is what is so frustrating about this. I have never run into this issue. I have already dipped them in iodine based reef dip and coral rx. There are no bugs no flat worms no spiders no nudibranchs and it's definitely not zoa pox. My parameters are perfect as always.

Kh 8.5
Cal 450
Nitrates 5
Phosphate.05
Magnesium 1350
Temp 78

17451089263945144711467796366249.jpg 17451089921992652130806395616013.jpg 17451090141891755663463575993363.jpg PXL_20250413_194954672.jpg

Did one of your fish get a taste for Oas?
 

liddojunior

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@VintageReefer He can vouch that the starfish can become zoas predators
 

VintageReefer

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I happen to be online and saw I was just tagged

It is possibly the asterinas.
There are many species of these, many look nearly identical, and most are harmless. But there are a few that are zoa predators. And they seem (for me at least) to only go after higher end zoa

I was Reefing 20 years and never encountered the bad ones. Until one day I was losing exospheres. Turning to mush and vanishing. I must have got one of the bad asterinas introduced to my system unnoticed. Isolating the zoa colony (well what was left of it) immediately stopped decline. And then it started recovering. I got a harlequin. I couldn’t determine good from bad asterina. So they all had to go. Issue hasn’t returned
 

ReefQuestCorals

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I think I spy with my little eye astrina starfish literally eating your zoas in the photos.

edit: You can clearly see them on the zoas that are closed and some are in the zoas polpy going to buffet town

I saw the same in that pic. I can say iv never dealt with this issue, but have known others that have.. Little boogers can munch down on some zoas
 

VintageReefer

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Dip the colonies to kill any starfish mixed in them. Get a harlequin asap.
 

VintageReefer

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Just a correction/addition

I must have got one of the bad asterinas introduced to my system unnoticed.
…And then it multiplied blending in unnoticed with the rest


FWIW the ones that eat zoa had red backs. And when I had the problem start someone told me to look for ones with red backs. These ones seem to be higher risk
 

TangerineSpeedo

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I was a "not alarmists" about asterinas . But then I saw a couple on some of my zoa polyps. So I am conflicted... Some of them are a great member of the CUC... But obviously some went rogue... Or did they? Were they in a situation like George Micheal and being an opportunist? "It's not what it looks like, I was just sucking on some algae" Well it doesn’t matter, your making my zoa uncomfortable... You gotta go...
 

VintageReefer

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I was a "not alarmists" about asterinas . But then I saw a couple on some of my zoa polyps. So I am conflicted... Some of them are a great member of the CUC... But obviously some went rogue... Or did they? Were they in a situation like George Micheal and being an opportunist? "It's not what it looks like, I was just sucking on some algae" Well it doesn’t matter, your making my zoa uncomfortable... You gotta go...
Good read
 

eqbal9947

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If there are no pests, id do an antibacterial dip.
Sometimes i have my higher end corals close up and i KFC dip them.
More often than not, they recover
 
OP
OP
F

fishwhisperatx

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Thank you so much for everyone's replies. I noticed the star fish but from my experience in the past they only attack corals that are already distressed. I have had the stars for 8 years and no issues but I guess I got a hitch hiker on a corals recently, because the population has exploded recently. Special thanks to Vintagereefer! That was a great read. I'm now convinced it's the star fish and will be getting 2 harlequin shrimp. My only concern is I have a flame hawk. Do y'all think he will eat them?
 

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