Welcome to Pet Talk. I agree with the others. Please get your 3 year old cat neutered. This will help to calm him down. Good luck and please keep us updated.

BTW my cat Storm,8 years old, and my cat Cirrus, almost 2 years old, also fight. Storm doesn't like Cirrus and chases him until he hisses and growls at him. Luckily Cirrus is very afraid of Storm so he doesn't fight back. All 4 of my male cats are neutered. Sometimes cats will never be friends and only tolerate each other.