I bought a lovely little blue female rat last week. She was pricey ($14!!) but she was so pretty. Kept her seperate and watched for sneezing, no problem, so yesterday I dropped her in with my solid male and his harem. Watched all afternoon, all seemed well. They were curious, but no fighting.
Well...Went in to do morning feeding today and found this.
It's hard to tell in the photo, but that is one of my original females standing gaurd over approx 30 very DEAD baby rats. Pretty gruesome, and not even ONE left alive.
I suspect the new little blue girl. That is an established tank that has been steadily and reliably producing for me for a very long time now.