I think your angler will be fine. I can't imagine a snowflake eating a tang unless the tank is a month old. I know it is situation but my snowflake never touched anything living including shrimp,crabs and snails. I also never feed him live food to get him in the habit. I had him in a tank with with small fish such as firefish, gobys and clownfish for 7 years never had an issue. Now he's at my dads with sharks and another moray no problem.
He is the biggest fish I have owned and problaly the least noticed fish. When ever people came over I had to point him or they would of never known he was there.
[video=youtube;mvSHsaE1O7M]http://www.youtube.com/watch?v=mvSHsaE1O7M[/video]