Zoas turning brown, closed and melting

[sapphireminer]

Have an island of zoas, most of which are doing well for the past 2 week I've had them, but some are starting to close and look like they're melting along with browning on the side of them.

Today, I noticed a small, brown wormy scurry back into the zoas. I didn't get a good enough look at it to ID, so I can't be certain. I'll try to see if I can spot it this evening. I also have hydroids in another area of the tank, but I haven't seem them on these guys.

Parameters are all great...calc, alk, mg, NO3, PO3, sg, temp, you name it. All other corals are happy.

Thoughts?

 

[blaxsun]

"Walk without rhythm and you won't attract the worm..." I'd probably dip that coral if you can.

 

[vetteguy53081]

Have an island of zoas, most of which are doing well for the past 2 week I've had them, but some are starting to close and look like they're melting along with browning on the side of them.

Today, I noticed a small, brown wormy scurry back into the zoas. I didn't get a good enough look at it to ID, so I can't be certain. I'll try to see if I can spot it this evening. I also have hydroids in another area of the tank, but I haven't seem them on these guys.

Parameters are all great...calc, alk, mg, NO3, PO3, sg, temp, you name it. All other corals are happy.

Thoughts?

I never place mine on sandbed as they are easily irritated by sand that may land on them.
There are a number of factors why zoas close up. Some are water movement/flow as zoas do not require the consistent high flow conditions that SPS corals do. I would consider a moderate flow environment ideal but Zoanthids, like most corals, can adapt to low or high flow. In high flow, you will typically see polyps grow closer to the rock with shorter stalks. Another is lack of feeding and food as infrequent feeding and ultra low nutrient conditions can lead to entire colony meltdowns. Target feeding is not a requirement as Zoanthids are photosynthetic. I have found that target feeding Zoanthids always provides mixed results, when a food particle falls onto the polyps.

Back to parameters, good water quality is a must.
dKH: 8.0 - 10.0
Calcium: 420 - 440
Magnesium: 1300 - 1350
Iodine: Maintained via regular water changes or manually at small dosages
Temperature: 78-79 degrees
pH: 8.1-8.3
Phosphates: .02 - .06
Nitrates < 10

Asterina stars, little tiny tiny spiders and nudibranchs also will make them miserable to point of death as will aptasia, worms like spinoids or vermetid snails. A few things to look for. Hope this helps

 

[sapphireminer]

Not worried about parameters — all within range, except for higher calc (480) and mag (1500). PO3 at .06 and NO3 at 4.86 yesterday.

It's a nano tank (15g) so flow is moderate even at the sand bed with my directional return. The other softies (GSP, Xenia) on the sand bed seem to be fine. They aren't that close, so not too worried about irritation. Zoas were in the bed for about 2 weeks without issues. Added a few other LPS a few days ago and started noticing the zoa issues shortly thereafter...which leads me to believe hitchhikers, see below.

I dipped the zoas today and 6 or so worms came scurrying out. Maybe amphipods? See attached.

Harmful (and causing the issue) or helpful (and I need to look elsewhere for problems)?

Video: