I bought mine at 6" and it was always aggressive since. I don't remember it ever being shy back then. It was always swimming back and forth whether or not the lights were on or off.
It never jumps out of fear unless I try to catch it.
They are very fun to feed and watch when they are not shy. Mine was/still is very aggressive to the point where it would always rub its face against the glass and try to bite whatever that is in front of the tank. It still does it til this day.