Toenail color is determined by genetics and is not breed-specific. Just like humans have different hair and eye colors, dogs can have different toenail colors.
Pit bulls, like any other breed, can have toenails of various colors, including black.
It's important to remember that a dog's breed does not define their personality or behavior. Instead of focusing on physical characteristics, it's best to judge each dog as an individual based on their personality and temperament.