Dying Acan?? Help!

[Arielneedscoralsanon]

I was gifted this cube tank I think is about 12 gallons, about a month ago from a friend who had it for about 5 years prior. The tank is super stable and water quality is stable. It’s got a solid fan head but has been running off natural filtration(sand, rock, etc) since it was started.
Water as of Friday tested by lfs 8/22: salt 1025, ph 8, kh 8, nitrates I don’t have the number but it was also in good standing.
Last week I noticed one side of my beautiful bright orange Acan was browning. Nothing crazy but noticeable and not happy looking. Tank friend as well as lfs said to increase lighting on the side that’s not looking good and maybe feed it. I will admit I haven’t fed yet just because I wanted to try the elements one at a time and see if it picked up. Plus like I said there’s not an actual filtration in this bad boy so it’s been fed by the hermits and crabs and what not for most of its life and I don’t want to risk nuking it.
Any who, since I first noticed the browning, it’s gotten much more colorful but not in the way I thought it would go. Now it looks almost rotten and I don’t know how else to put it. The heads in the darker side are now yellowy/blackish/greenish like a bad wound or something. But everyone so far I have asked says the polyps are fluffy and good, tentacles are out and look healthy, it’s just this horrible coloring and the fact the heads on the dark side have gotten deeper and not so round.
I started moving the light over to the side of the tank so it’s directly on that side for a few hours a day and I do think it’s gotten slightly better but I am not convinced. I am at a loss. And I’m terrified it’s going to start dying and crash the whole tank so any ideas or advice is greatly appreciated. Everything else in the tank is open and doing fine. The only thing a little pissy is my lepto jack o lantern but that’s a very new addition to the tank and I’m working on placement for it.
The only known possibility of irritation is I had a couple huge emerald crabs in there for a few weeks that would just abuse and pinch and pull on the corals. They are now returned to the store and swapped for little babies but I saw it specifically target this Acan a good few times.

 

[Arielneedscoralsanon]

TLDR since I didn’t realize how awfully long the post is:
Inherited a stable 12g cube tank (5+ yrs old, natural filtration). Current parameters (8/22 LFS test): salinity 1.025, pH 8, KH 8, nitrates in good standing. Acan coral started browning on one side → now turning yellow/black/green like rot, though polyps/tentacles still look fluffy and healthy. Tried adjusting light but not sure it’s helping. Worried it’s dying and might crash tank. Possible cause: past irritation from large emerald crabs that were picking at it (now removed). Everything else in tank looks fine except a new Jack-o-Lantern Lepto still adjusting.
Need help figuring out possible cause and if it needs to be removed from tank or anything else.

 

[project1004]

You should never adjust your whole light just for one coral…. You can move the corals to somewhere else would have been much better option.
Maybe One acan is not doing good but you taking over the tank (small one at that), and only have one coral problem is a blessing. It could get worst. So I would not make too much changes too fast.

The acan wouldn’t nuke your tank but if you like, put tiny activated carbon for assurance. That Acan maybe stressed but it’s not dieing.

I would try to do as least as I can because your tank is so small, it’s easy to make it worst by doing little things.

 

[Arielneedscoralsanon]

You should never adjust your whole light just for one coral…. You can move the corals to somewhere else would have been much better option.
Maybe One acan is not doing good but you taking over the tank (small one at that), and only have one coral problem is a blessing. It could get worst. So I would not make too much changes too fast.

The acan wouldn’t nuke your tank but if you like, put tiny activated carbon for assurance. That Acan maybe stressed but it’s not dieing.

I would try to do as least as I can because your tank is so small, it’s easy to make it worst by doing little things.

Thank you for the advice! Luckily the light just swivels and bends to different positions so it goes right back, but I will hold moving it anymore and leave it over top where it typically is.
I know moving the Acan itself would be best, however it’s very much attached via the cap being glued flat to the rock by previous owner, and I wasn’t sure cutting it off would be smart to do while it’s angry. Should I bite the bullet and cut and move it or wait it out? Also should I feed or wait until it bounces back?

 

[Arielneedscoralsanon]

You should never adjust your whole light just for one coral…. You can move the corals to somewhere else would have been much better option.
Maybe One acan is not doing good but you taking over the tank (small one at that), and only have one coral problem is a blessing. It could get worst. So I would not make too much changes too fast.

The acan wouldn’t nuke your tank but if you like, put tiny activated carbon for assurance. That Acan maybe stressed but it’s not dieing.

I would try to do as least as I can because your tank is so small, it’s easy to make it worst by doing little things.

Also I’m giggling at you mentioning the size of my tank a good few times, and yes it is smaller so no worries I get your stress because I have it too lol, but the bozo at the LFS is the one who said move the light for a few hours a day and said to start feeding and/or adding fish. Fully had some clown fish and goby picked out for me. I’m like dude my tank is slightly over stocked with coral already with no actual pump please f**k off it’s maddening how wrong of advice comes from different places so I really appreciate you giving it to me straight

 

[dball711]

I don’t think that acan really looks too bad at All. Maybe take it off where it’s mounted and leave it on the sand bed and see how it does down there, but again I don’t think that acan looks bad at all.

 

[Arielneedscoralsanon]

I don’t think that acan really looks too bad at All. Maybe take it off where it’s mounted and leave it on the sand bed and see how it does down there, but again I don’t think that acan looks bad at all.

Okay gotcha thank you, it’s just the sudden bizarre coloring that had me flagged, it was all orange and suddenly was yellow and green just on the one side. So just to make sure: sudden color change can be normal? I didn’t know that so it’s fascinating

 

[project1004]

Ya your acan looks really okay. They do get stressed from things like light changes, temperature fluctuations, water nutrient or parameters changing to rapidly etc.

I don’t think it is necessary to move the scan since it’s been in that same spot with same light and was adapted and adjusted...

Keep things as is for sometime is probably a good idea.