I've had the same 2 percula's since I stared this hobby 12 years ago. They survived multiple moves and some pretty bad mistakes. Over the past month or 2 I've noticed the female harassing the male more so than usual. Today I noticed the male is starting to get pale. As I was checking it out the female bit the other ones tail. Whole damn thing in her mouth, I thought it was over for him. So what gives. The only thing that's changed is they are in another new tank. They've been in there for the last 6 months though and this just recently started happening.