Her rbta was recently moved to the tank it's currently in because of an ammonia spike in the tank it was in (there's a thread on here).
The sure sign of death is the anemone physically coming apart and starting to melt away + a very bad smell.
I'd have to see it but if it's really really looking like it's going to die, then I would go for the doxycycline dip-
Here's a quote from the thread:
"Used to have bad luck with them and other anemones till we quaranteened them which consisted of the following procedure. Without it, we were 0/8 on new Heteractis magnifica (now the accepted name, until they decide to change it again)
Upon arrival, all bag water is removed so you're left with a bag full of almost only anemone. The anemone is then added directly to a bucket of good quality tank water and aerated. If the water fouls or gets too much mucus, then discard that water. The anemone is then added to a 5 gallon bucket of good quality tank water which has been previously mixed with 10mg/gal of doxycycline. Most capsules available are 50mg, so a 5gal bucket works nicely. Water is gently aerated for 24 hrs mindful of keeping temp acceptable, which is done by floating the bucket in a sump or larger container of heated water, you don't want the heater in with the anemone. After 24 hrs, remove most of the water and refill with another 5 gal of good quality tank water with 10mg/gal of doxycycline. Leave for another 24hr then remove the anemone to a tank that is large enough to keep them for what could be a long time.
With this procedure, we were 6/8 and that was over 2 years ago and they're still here, with the largest now almost 30" in diameter.
As with any medication, especially anti biotics care must be taken not to overuse.
Joe"
RC Thread
Hope this helps. I've never done this before but someone says in the thread that it saved their anemone from an infection. Since it looks like it's getting ready to die now you have nothing to lose trying it.