guppy bully

Hey guys, I have a 10 gallon tank (20" L, 12" H, and 10" W) that has 6 guppies, 2 male 4 female. 2 I have had for a while and the other 4 are relatively new. The 2 I've had for a while is a male named Enzo and a Female named Gretta. Gretta is currently pregnant and so I had gotten more females...