As a rebreather diver on Bonaire with 3461 kills (along with my open circuit wife Berit) I can assure you it's not that easy to "sneak" up on them. They are either "uneducated" or "educated" and the rebreather makes no difference when the educated fish see you coming their way!
I'm always looking for a rebreather buddy; email me the next time you're on the island!! mpement@aol.com.