I think Dr Bill speaks words of wisdom - know the animals, their habitats and habits, and respect them accordingly!
It's the Titan, or Moustached Trigger (Balistoides viridescens) you have to watch out for. They can be a substantial sort of a fish - 2 1/2 feet. I'd dived happily with them on many occasions in the South Pacific and they really didn't seem to give a toss if I was there. It was through an account in an Oz dive magazine that I became aware that they posed any potential threat to divers, as one victim described having been hit out of the blue by one.
Later, when visiting the Red Sea, diving literature and anecdotal evidence suggested that they were certainly a factor to be considered during their breeding season (from July through to September, and especially September). Hardened DMs who didn't bat an eyelid at the areas oceanic white tips warned us in the strongest terms about getting away from nesting Titans. Mostly they'll go after fins, but they will also target the eye and facemask area. A good thwack on the head with one of these at full pelt and you'll be lucky to escape with just a bleeding scalp - some have had face masks cracked and have even been K.O.d (never heard of a fatality!).
We were specifically warned when diving the Brother Islands in August that a Triton was hanging around one particular area and was, it was suspected, looking for a nesting site. When we ran into it, it was apparently settling in. We kept a wary eye on it from 10 metres above and finned rapidly to get past it. Nothing more than a bit of eyeing off from the trigger, and no charge.
When pursued by a Triton, the only course is to get out of its turf as quickly as possible. This should be by swimming sideways rather than up, as their territory apparently extends in a sort of cone shape, from the nest to the surface.
