It doesn’t look like Ick to me. Looks more like a wound. Could be a bite from another fish, but there are some bacterial or fungal infections that could cause that as well but I’m not an expert and couldn’t point you to what it could be.
If it was me, I would observe for a few days and see if you can see it either getting better or worse. If you see improvement then i would guess it’s just some kind of injury. If you see it getting worse I would look into issues that could cause similar symptoms like a bacterial or fungal infection.
Sorry I don’t have more of an exact answer. Hope this helps. Take care and happy reefing.
As was said, that's not ich. As @Bfragale said, it bears watching closely over the next few days. It is most likely a bacterial infection from an injury and it may heal on its own. Watch for a lack of appetite or rapid breathing or an expansion of the lesion . If you see that, you will need to act, otherwise, probably best to just observe for now.