Any trigger fish will attack an invertabrate if you do not follow a special techique.
I keep 2 niger triggers and 1 Humu-humu trigger with hermit crabs, snails, and seastars. Yet my triggers never attack my invertabrates. Do you know why?
First of all, trigger fish love eating! However, they do not like finding there food. Therefore if you feed your triggers often, they might just not even bother attacking your invertabrates.
Another method is to put the invertabrates into the tank before your put your triggers in. This works since a trigger fish always has the idea that he is king and he gets to eat anything he wants. If you put the invertabrates in first, your trigger fish will notice that he is not king since occupants have already taken up space in the tank!