Over the years I've basically kept every trigger that is considered "reef-safe" and a couple that aren't like a huge black durgeon and I wouldn't add one one again because of several factors.
In my earlier reef-keeping days I never took a long term approach to planning. I loved the look and idea of providing as natural of a habitat for my animals as possible and at the time fish were my the primary focus while corals and inverts was secondary. I would "experiment" with all of the iffy reef safe fish like Angels, butterflyfish, and of course triggers. This was over the course of about 10 years and I experienced some short term success with keeping these types of fish with various corals and inverts but I wouldn't consider any of these "successes" long term as I always found myself changing tanks, aquascaping, and inhabitants thus not allowing for any real assessment of long term behavior of my ecosystem.
A few obvious observations that I made with keeping triggers in my reef tanks were:
1. Triggers eat a lot and can cause bio-load problems. In a softy or LPS tank it may not be an issue but if you have an SPS dominated tank triggers can create a higher maintenance regiment in order to keep nutrient levels low enough for the corals to thrive.
2. My current definition of a reef tank is much different than it was a few years ago. Back then I figured that having coral made it a reef tank but now I view a true reef tank to be a more balanced ecosystem with corals, snails, crabs, worms, pretty much everything you would find on an actual reef that will work in a closed system like our aquariums. Having a trigger can keep you from achieving this type of setup as they will more than likely eat your snails, worms and crabs, and eventually may eat your shrimp. I also like to have smaller fish like gobies, blennies, dartfish, etc. in my reef tanks and keeping triggers will also more than likely cause problems as they may eat the smaller fish. One other thing that I observed is if you have any fish that are docile and timid like some Anthias, the presence of a trigger may add undo stress and these fish may stay in the rock work more and eat less.
3. Triggers can be destructive to coral and rocks. Many of the "reef-safe" triggers do not eat coral but they can and often do rasp on hard corals and live rock in order to keep their teeth worn down. The two big crosshatches that I had loved doing this. They also loved shooting water from their mouths into the sand looking for inverts to much on. Once they learned that the food came from the top of the tank they would shoot water out of the tank thinking food was going to appear.
4. Agressive - Triggers have big appetites and can be aggressive during feedings. Over the years, I lost a handful of fish due to being accidentally bitten by a trigger during feedings. I eventually started feed them separately with a turkey baster and would wait until they were full before I fed the rest of the tank. They are very smart fish and would put their mouth right up to the opening of the baster and sucked the food right up.
Triggers are amazing fish and have always been a favorite of mine but I no longer see the any real upside to keeping them in a reef, they limit your options too much over the long run.
