It doesn't look bad to me. I'd do one of 2 things.
If you really think it's dying, pull it out and put it in a small container (tupperware, beer mug, bowl... whatever). Then every morning and every evening dump most or all of the water down a drain and refill it with water from the tank. I've kept a pair of anemones like this in an old peanut butter jar for 8 weeks and they did just fine.
The other option is you are overly concerned. Anemones can act weird and look bad for hours and even 2 or 3 days and then go back to being perfectly normal.