Triggers (Balistidae) are opportunistic feeders. They will eat what is most readily available. Many species prefer crustacea, but most species will feed upon what is present.
I used to be a commercial collector of "ornamental" marine invertebrates in the Lower Keys (FL). I would be followed by Queen Triggers (B. vetula) on a regular basis. These critters are quite intelligent, and recognized me/us, and our equipment, as "the humans who lift up the rocks" (collecting Mithrax/Emerald Crabs, Brittle & Serpant Stars, etc). It was obvious that the triggers (along with snappers, grunts and hogs) prefered Mithrax sp., but would readily feed on Percnon sp. (Sally Lightfoot/Nimble) crabs, Gonodactlus sp. (MANTIS) shrimp, and Alpheus sp.(Pistol/Snapping) shrimp. I found it odd that Brachyura sp. (Arrow, Decorator, etc.) crabs were largely ignored. Echinoderms (seastars, urchins and cucumbers) were NOT targets, contrary to scientific and hobbiest findings.
I want to clarify that I was not dealing with the 6-8" Indopacific Mantis Shrimp, but I have personally seen one species of trigger- Queen/Baliostoides vetula- feed upon mantis shrimp multiple times in the wild.
PS- FOR EVERYONE ON SWF.COM... It is rare for me to INTENTIONALLY start a flame war. When I am adament on my point of view I often come off as a troublemaker. Reefer123, I am not attacking you, I simply want to clarify WHY I disagree with you. Please don't take it as a personal attack.