[Delphinus]

I have a mandarin in with 3 BTA's, no problem.

Generally, BTA's are not aggressive predators of fish. In a sense, they're very peaceable, ideal reef tank inhabitants. The description I would use is "opportunistic scavenger." They are content with already-dead food that happens to fall on them, they don't seek out the food and they certainly don't make much of an effort to make live things become dead food. Basically, you can go by the amount of stickiness. It would take a very ill, or already dead fish (of just about any kind), to not be able to pull away from them. Besides being not sticky, it takes a least 30 seconds to a minute to swallow something, and if you're a fish thrashing about trying to avoid becoming a meal, that's usually a very long time.

There was some guy on RC last week claiming his BTA ate his .. tang or something, I can't remember. It seems very unlikely to me though, it's quite a fantastic claim in my opinion. Perhaps he has mis-ID'ed his anemone or perhaps something we don't know about happened to his fish.

Anyhow, my $0.02, hope this helps.