I've always kept several roosters, sometimes hatch mates, sometimes not. They figure out the pecking order pretty quickly and so far with minimal violence. The only problem I have had is when I have more than 2 out at a time with my ladies. When the second or third roo tried to mate with any of the ladies, one of the others would knock him off. So my fertility was compromised. Since then I keep only 2 roos out at a time. The others are in a bachelor's pad. I rotate their play time. It works fine, as long as my King Roo is always out. I love my roos!