Odd Acan behavior?

[NanJ]

There are three Acans in our tank scattered in different spots. They have been in the tank for 4-5 months, all have put out babies around the bottom and the babies have grown. Until about two days ago they followed a predictable behavior: get big and fluffy during the day with tentacles extended then shrink in the evening as the light intensity decreased. But for two days now they are tightly drawn in. All three did this at the same time. No other corals in the tank have changed their behavior. No tank parameters have changed.

Attached are photos of one of them the last two days versus how it has looked for several months. This particular Acan usually gets so big and puffy we call it the "elephant ear". Now it is tightly shriveled. Does anyone know if Acans go through maybe a resting period or hibernation type behavior? We thought it might be a fish or CUC picking on them but that seems odd - 3 of the same type at the same time.

Thanks for your thoughts.

Top: Fluffy and happy. Bottom: Tightly shriveled.
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[Travis Stewart]

mine do this from time to time and really look like something major is wrong. For me, it’s just a coral having a tough day. It also happens about the time I need to do a water change. Then a couple days later back to normal. Usually just one or two colonies that do this at a time. Hope this helps!

 

[NanJ]

mine do this from time to time and really look like something major is wrong. For me, it’s just a coral having a tough day. It also happens about the time I need to do a water change. Then a couple days later back to normal. Usually just one or two colonies that do this at a time. Hope this helps!

It does! Always good to compare coral behavior with other people.

 

[Tahoe61]

Have you added any new products like GFO?
Changed lighting?
Is a fish or invert picking at them?
Need basic chem values to trouble shoot.

 

[NanJ]

Have you added any new products like GFO?
Changed lighting?
Is a fish or invert picking at them?
Need basic chem values to trouble shoot.

No system changes, lighting schedule verified to be sure intensity, etc, didn't get accidentally changed. Tank parameters are maintained at recommended levels with Apex DOS/Trident. Nutrients checked weekly and remain steady.

A couple of months ago we had to re-home a large Hippo Tang because it took a liking to corals. It took several weeks to catch him in the act. Hope the Acan issue isn't from another fish!

 

[Travis Stewart]

Are you doing regular water changes?

 

[NanJ]

300g DT: daily 2 gallon AWC, once a month about 20-25%.
Next monthly water change is in a week but this is the first time the Acans have behaved like this.
Never a shortage of "Why??" in this hobby.