Livebearers
I have a male fancy guppy named "Zippy" in a tank with 2 mollies and 3 platys (he had a guppy friend once upon a time). He is ALWAYS chasing the platys (all male) around the tank, especially "Argo" who is twice his size, and nipping at his size.
Is this normal fish antics or is my guppy a bully?