What is this? RTN?

[claudiojr]

What is this? What should i do? This is a new piece in my aquarium, i´m afraid this thing goes to my other corals.

 

[benihana]

Not sure if it is RTN (rapid tissue necrosis), but is sure does look like some type of tissue necrosis. I would frag off what you can and put them in a different tank if possible. Just make sure to frag a ways away from the dead tissue

 

[Constrictor6090]

Almost looks like it may be AEFW since it's losing the tissue underneath the branches more towards the base, maybe.

 

[scottwhitson]

I would guess it was caused by a large shift in parameters from the tank it came from compared to yours. I second benihanas advice, you should frag it to hopefully be able to save it. Also it appears that there may be an aptasia on rock that the acro is mounted to.

 

[bboudreaux]

That looks like a maricultured piece. If so that is what usually happens to me when i try one of those.

 

[Greg11]

Looks like wild colony to me,its hard to keep them and hard to color them up, I would cut off as much as you can and move it lower for couple of days

 

[claudiojr]

It is indeed a maricultured piece. Are they harder to keep than the wild ones?
About that thing, its not an aiptsia. I´m not sure what is it, but i´ll put a pic of it later.