I have had a couple of anenome in my time and am pretty strong on the subject. They need strong INTENSE lighting for long term success. The metabolism is so slow for these creatures most do not realize why thier anenome die after a few months and attribute it to something else.
I have had successes and many more failures, (seen above is an earlier failure I keep to remind myself), and commend you for accepting such a challenge. Hopefully you will learn how to care for these complex creatures and do not take it lightly.
They get a lot of thier energy from zooanathelle and the remaining from their ineffiecient digestive system. By overfeeding regularly you CAN keep one alive under less than T5 or MH lighting, but I think it just draws out the inevitable and they slowly starve which is the cause for most of the losses.
They are an advanced level of care creature despite its abundance in LFS and low cost. A lot of the losses are from shipping stresses. My latest Sebae is a bleached out rescue that I have been able to color up and double in size. I think the Sebae are the better than BTA and do not move around as much. I don't expect you to take it back, but if it starts to wander constantly, bleach, doestn't eat or hide......you may want to consider doing so. I have had great luck with mine eating PE mysids which is meater, but smaller compared to the silversides most feed.
Getting yours to eat and eat regularly should be your biggest concern now.
Yes there are eceptions and there are people who have kept anenome under bic lighters and never fed them only to have them colorful and split a hundred times......but those are few and far between and ON AVERAGE and what usually is true, Justin is correct. If it is a relativly new tank and you are a new aquarist, that also draws an eye to it. They are sensitive, but not as to where the are the proverbial "canary in the coal mine" as Xenia is which cause and effect can be readily seen, the symptoms of distress are slow and once seen it is commonly too late.
But I was once in your shoes, I only hope you will succeed with your new creature.
Please do not hesitate in asking questions about behavior or care. As Justin said, we only want to save you the frustration we went through and see you succeed.