One of my percula used to attack the hand every time. In this case, it was just a phase.I put a fox face in a 75g tank years ago and it was the most aggressive fish I’ve ever had, I had to take him back. Any time I worked on the tank or put my hands in, he would rapidly swim left to right, stir up sand storms and attack me. I understand it’s not the norm…but I’ve experienced it.