I have a niger trigger for a year and half that is 100% reef safe. Does not touch my clam, shrimp, coral, snails etc...but he eats like a little pig
very sweet fish! very gentle and no aggressivity with other fish, even new introduction.
But...there is a but...all fish have their own personality and some other niger trigger are said to take bites out of fish and eat shrimps etc...mine is not like that. When I chose, I chose the gentle fish that are a bit shy and not the bold dominant fish of the tank.