The 3 or 4 that I've stocked readily ate mysis, brine, krill. Not really picky at all. They were very shy at first and only grabbed pieces that came near their hiding spot. Also they seemed to become much bolder when they had some larger active tankmates (tangs, angels etc.)

Try some live ghost shrimp (saltwater ones if you can find them), not too many triggers can resist those. Some of the FW ghost shrimp will last a day or so in saltwater, others die pretty quick.