my boys wont stop fighting

Question
hi, i have two male rats around about 6 months old. i got them from a rat breeder and they were not from the same litter, one was 5 weeks and one was 8 weeks. the first few months i had them they got on fantastically, however lately i have been having problems. the bigger older male keeps bullying the other, he will pin him down and bite his belly, the little one will lie with his front arms in the air and his mouth open, there is always loud squeks coming from the cage. i have recently found lots of sore red marks which look to be bites on the little ones back and top of his tail. they have a very large cage with countless toys, beds, hammoks and tubes, treats and food, i just dont know whats went wrong, they both get out for exercise and playtime everyday. the bigger one is a very friendly confident rat however the little one is very shy and likes to hide from me. what can i do to try to stop them. i have thought about taking one back and just keeping one also seperating them or keeping one and introducing a young baby, what advice do you have? thanks for any help
melissa.

Answer
The bigger male maybe establishing dominance because they are both now sexually mature. Here is what I would advise, Separate them for a few weeks, about a month. Let them grow up and get past this phase and then start to reintroduce them. This time away from each other will also let wounds heal. The Problem sometime with introducing a young baby is that the older rat may beat up on it. I had a friend that did this and came back an hour later an the baby was dead so I would not adive getting a baby while your rats are in this adolescent phase.

Best Wishes

Emily