I've provided enough hiding spots but the little 3 bar never hides, he's front and centre 24/7 patroling "his" tank, lol. As a result the Black Ghost Knife hides all the time and I never see him. Now that the BGK is back in the 175g Angel tank I get to see him calmly cruising about.
Since my 3 bar is so stable and outgoing I plan to keep him alone in the 144g with a 10" Royal pleco, which he ignores, and grow him out into a Monster. When the time comes the 175g will be his.