Agressive Girls

Question
I have had 2 female rats for over a year now, Elvis and Yoda. One has always seemed to suffer from mycos, and is slightly slimmer (yoda), yet her appetite, energy and general quality of life never seems affected.

For the second time in around 6 months, I have had to separate the 2 of them because their fighting was scaring me. They usually play fight and squeak a little, but these two times I have been kept up at night worrying. When I check on them it always seems to be Elvis chasing and attacking Yoda. Elvis is definitly the dominant rat, but I dont want to wake up to a dead or injurd Yoda. At the moment Yoda is in a cardboard animal carrier in the bath with food and water.

Cold they both be in heat or just purely fighting for dominance and am I doing the right thing separating them?

Thank You.

Answer
Usual rule is if there is no bloodshed all is well. The longer they are seperated the harder it will be to put them back together. All rats fight, sometimes viciously, but as I say, no blood, no problem. Rats go in heat every 5 days for 12 hours at a time, so doubt its that.