New Fish In Tank

So my brother, Ian, thought of getting a new fish. It's the same kind of fish as the old one in our tank, aggressive, wants to rule the tank, rude, bossy, fish. Our blue fish (the old one) follows the new one (Jewel) and nips at its tail. I'm so sorry for that little guy. The blue one thinks she is the queen of the tank (Witch she is since she is the biggest) but shes not a nice queen, shes a aggressive queen. I hope they get along some day. My brother would be very very sad if his fish, Jewel, died from my fish, diamond.