Relentless Percs

[aquarius]

I introduced a pair of false percs (Brady and Moss) into my 20G in December and since then they have gotten along perfectly fine. Just this weekend, the female (Brady) flipped a switch and has been relentless on the smaller male (Moss). For the past two days she has not left him alone, chasing around the tank and nabbing at him every chance possible. She's pinned him behind a filter and in the liverock and won't let him near any food. His fins are now torn up and his scales are scraped up a bit. After watching this, I went in and pulled him last night and put him in my 40G. I need to get him eating again and rehab him, but is there any chance I'll be able to reintroduce him to the 20G? Why after 6 months would this happen out of the blue? The percs were paired up when I purchased them at the LFS. Should I take the female back to the LFS and try another?

 

[lexluethar]

My guess is they were not 'sexed out' until December. Were they both the same size when you first purchased them? If so then while one is changing to female it will try to gain dominance over the male (smaller one like you said). Although it can get a bit rough i would let them be, unless you want to prolonge them fighting for dominance.
If they were already mated and a pair (one larger and one smaller) then i'm not sure why they all of the sudden started being aggressive.

 

[rinercl]

Okay, so I am no expert but I will have to agree with Lex.
I have two Percula clowns that I bought as babies about a year and a half ago. They were as happy as can be up until about two months ago. Since then they have been fighting pretty hard with each other. Neither has managed to do too much damage to the other, but they go at it pretty good sometimes. They will circle each other and bite each others mouths and chase each other around the tank.
It is my understanding that this is all normal. When they reach maturity they will start fighting to establish dominance. One will eventually win out and become the female. The other will be male. Then things will be much more peaceful and everyone will move on with their lives. My bet is that they hadn't yet made the change to a true male female pair. How do you know for sure one was already a female?
The thing I am not sure of his how much fighting is too much. I am not sure if anyone has ever had one clown kill another, but I would think it is a rare occurrence. I am just planning on leaving mine together unless one looks like it is about to die.