Just to chime in...
I disagree with the majority of the posters on this thread. The clown trigger, while aggressive, can be housed for a long time with suitable tankmates. IMO, two together is actually a pretty good combination (relative to other potential tankmates). While I have never had a clown trigger for 25+ years (their lifespan), I have had them for several years at a time and never had one killed by any other fish including other triggers.
Ophiura is right about something, though... if you get one you do have to be ready to accept tankmate casualties along the line. But like I said, two clowns together, especially if added close in time, are probably as close to ideal tankmates for these guys as you can find.