Zoa decline

[Han]

I have a 60 gallon tank thats approaching 3 years old. I could grow zoas so fast it was crazy for the last 2 years or so, but in the last couple months they’ve been steadily declining. Just kind of disappearing, sometimes whole colonies overnight. No changes in water quality (other than a gradual decline in nitrates, which now hover around 5), stocking, equipment or anything so it’s really baffling. On the other hand all my sps (which i’ve had trouble with in the past) are booming and
experiencing tons of growth.

This is a picture of the tank from February, all of the zoas are now almost gone except for the green palys (they don’t seem affected for whatever reason). Clove polyps are gone too, gsp has been declining as well (not that I really care). My goniopora has also become quite bleached though that may be related to being abused by my clowns Thoughts?

 

[Bfragale]

I had same issue. Couldn’t figure it out. Then I saw a damsel fish eating a zoa. Got him out and never had the issue since lol.

the damsel fish is not known for eating corals and in ever suspected him until I saw it happen.

by any chance anything that could have developed a taste for zoas? The palys have higher toxin so fish may ignore them and go after zoas.. just my thoughts.

 

[fishguy242]

hi,possible zoa eating,nudis/spiders?? they tend to avoid palys,freshwater dip one see if any thing found? hope not

 

[Han]

I had same issue. Couldn’t figure it out. Then I saw a damsel fish eating a zoa. Got him out and never had the issue since lol.

the damsel fish is not known for eating corals and in ever suspected him until I saw it happen.

by any chance anything that could have developed a taste for zoas? The palys have higher toxin so fish may ignore them and go after zoas.. just my thoughts.

I don’t think so, no new fish have been added in about 2 years. I have a longnose hawkfish, 2 clowns, midas blenny, royal gramma, and melanurus wrasse. I did lose some of those ugly brown palys (thankfully) so I’m really confused why the green ones are doing fine.

 

[Han]

hi,possible zoa eating,nudis/spiders?? they tend to avoid palys,freshwater dip one see if any thing found? hope not

That was my first thought, I’ve tried freshwater dips and revive but didn’t see anything out of the ordinary. I did have a problem with zoa eating nudis when I first started the tank but haven’t seen them in over 2 years thankfully.