I have a 6 1/2 month miniature bull terrier crossed with something I believe he may be crossed with a pitbull... He's over all a pretty good pup but he has shown major signs of aggression.. Never towards adults or very small children but he has nipped at my niece who's 6 when she was running which I corrected but passed off as play biting but today he got in a fight with my cousins dog which is a stafforsire terrier and also my moms dog which Is an older beagle but both dogs were aggressive towards him first and he just grabbed them with his jaws by the neck and wouldn't let go... It was scary but he's fine with more dosile dogs... I just don't know what to think about this one... Is it a matter of being a dominate male and an unfully trained pup? What do you guys think? Will he be better once he's nuetured? Or is there something I'm not doing right?