Chromis adjust their own numbers to fit the tank. My experience is 1 per 100 gallons will thrive and bother nobody else.
The Fiji blue devil is actually a fairly mild fellow.
Two to avoid: one-spot dascyllus or the damsel that has a white and an azure stripe on a black body. The dascyllus grow huge fast---I had to rehome one the size of my palm and unless raised from infancy with other damsels will attempt to kill them all. And succeed. The azure stripe damsel while beautiful is the meanest of a tough lot.
The Fiji blue devil is actually a fairly mild fellow.
Two to avoid: one-spot dascyllus or the damsel that has a white and an azure stripe on a black body. The dascyllus grow huge fast---I had to rehome one the size of my palm and unless raised from infancy with other damsels will attempt to kill them all. And succeed. The azure stripe damsel while beautiful is the meanest of a tough lot.