Sebae question

[kuatto]

I decided on a Sebae anemone and found one.After accimilating it all seems fine,except I noticed it spitting out brown colored crud from its mouth.Is this waiste or it's insides?It isn't completly white(bleached)still shade of tannish white with purple tips.I've read everything from they're the most difficult to keep to they're real easy,so I don't know what to believe.
I've placed it near the surface under mh with a gentle current and fed it some blended fish and a small piece of clam meat(which it spit out later).

Jim