Preferred cuisine for the BTA would be silversides and raw shrimp. Size of the pieces fed would depend on the size of the nem. Small nem = small food, etc..
In answer to your question, don't kow for sure, but I don't think it will hurt the BTA. What will, however, is putting an anemone in a tank not seasoned for 6-8 months. Water parameters are just not stable enough for them to survive. If I have mispoke about your tank, forgive me. It's just that sooo many people don't do the necessary research before adding creatures they don't know enough about.
I hope yours survives without problems, but probably won't in an unseasoned system.
An excellent research tool for the clownfish/anemone is Joyce Wilersons's book "Clownfishes". Excellent reference material if your interested in Clowns and nems and a very easy read.
Good luck and remember in reefing patience is the master of a successful reef system.