Sick Bubbletip Anemone

[linzld]

I have been having trouble with my bubbletip anemone and i'm not sure if there is something I can do or if I just shouldn't have an anemone in my tank, despite what my LFS that sold me all my equipment said...

I got him in April and for a few months he was doing great... and my tomato clown loved him. Then he started to shrivel up and has really faded out. He still eats whatever I feed him but just doesn't look good. I have a 40G tank with 4 X 24W T5 lighting and he is usually relatively close to the top of the tank. Does anybody have any advice or suggestions about what I can/should do? I have been feeding him PE Mysis and silversides.