I have a juvi Niger and Humu in a 100 gallon with a 5" Lunare Wrasse, but went in knowing I will be moving one of the Triggers to a 125 when they get bigger. When buying fish, always know what their max size is and go by that when stocking your tank - it's easy to think "hey, he's only 3" long now...", but in 1 year he'll be 10"! The Triggers especially are very active fish and need plenty of swimming room and territory. Although both the Niger and Humu are considered "smaller" Triggers, both can easily get over 10" (usually 12-15") and when you have a tank thats only 19" wide your cutting it kind close. Like keeping a German Shepard in a closet
The Humus also get very mean when they get older...