i have a female thats just over 4" long in my 75g... pair of clowns, scooter blenny, leopard wrasse, snails hermits longspine urchin... got a school of chromis and a couple tangs... melanarus doesn't bother a soul. wakes up early, bout an hour before the blues even turn on, active throughout the morning and then hangs out the rest of the day swimming in and out of rocks, asleep and hidden by about 5pm