A Pearl that would nip the fins of a fish to the point of death is highly unusual, in my experience. As I, and others have stated, Pearls are pretty shy fish which keep mainly to themselves and tend to leave other fishes alone. I suppose even amongst shy species, it is possible to have a rogue specimen which will terrorize other fish to get what it wants: more space, more of the food, the available mates, protecting it's territory, etc. However, that is a very rare and extreme situation, and it is highly improbable that you will end up with a Pearl that will be such a holy terror. They aren't fin nippers, and tend to be extremely peaceful.
During a breeding cycle, the beauty of the Pearl is hard to match, especially in the male. They develop a deep coloured body covered in pearly white spots which is probably how the Pearl earned its name. The male develops a firey red/orange thorax/abdomen...very stunning.