that tank is a bit small for a trigger IMO, you could keep a dwarf lion in there just fine. An full size would be to big for the tanks depth (front to back)
only issue with most of the predatory fish like puffers, triggers, groupers, etc, is they get large, and a 36 inch tank is just not long enough for there active nature. Puffers with the exception, but most should not be kept in anything under 150 gallons.