I've had them for over 10 years, never managed to eradicate them, only keep them in check. Here's what I've tried.
Peppermint shrimp: I've added peppermint shrimp from different sources many times over the years, I've never seen one touch them. Maybe they keep them from spreading and I just don't notice, but they don't work for me. That being said, they are cheap and nice to look at.
Aiptasia x: Works good, just gotta make sure and use enough to cover the foot. If you don't cover the whole thing it will be back in a week. I know there are other brands and DIY recipes but I've never tried them.
File fish: I've had 2. The first ate all visible aiptasia but when it died after about a year, they came back. The second file fish is still in my tank after about 2 years, he's never touch the stuff.
CBB: The first one I had was awesome. Eradicated the stuff and grew huge and gorgeous. Had him for years until he passed for no obvious reason. Again, when he died they came back. Basically, I've learned if you get a fish to eat the stuff, they will never get them all. The ones deep in the rocks, overflows etc will still be there. I tried CBBs twice after that and they were short lived, so I've given up on them for now.
Berghia nudibranches: Expensive. Tried them twice. I carefully acclimated them, put them near aiptasia, and never saw them again. Maybe I didn't buy enough, but like I said they're expensive. I was considering a 3rd try and I called one of the vendors that bred them. He said in a tank where there are only a few and spread out to not bother. It's only when there is a huge infestation does he recommend them.
My current routine is just to kill them with aiptasia x one every couple of weeks when I am doing maintenance. It's important to completely cover them so they don't come back and don't spread. I don't think it's worth restarting a tank over them. Just part of reefkeeping for many of us.
