I got a 4" Miniatus(similar aggression to a blue-line) and a 3" Clown Trigger in the same tank (120), along with a 22" Snowflake eel. The Miniatus has never bothered the Clown, and vice-versa. Groupers are "flash" feeders; they sit fairly still until food is in the tank; at which point they make a flash attack toward the food. I try and feed the Miniatus first(different food) and then the Trigger.