My cory cats and fancy guppies are my favorite schooling fish. You have a tank big enough to have a large school of male guppies and help eliminate some of the aggression problems. They're absolutely stunning in a school and you can have a lot of variety in color pattern.
Edit: Do not buy female guppies unless you want fry. They are live bearers. Therefore, they are much more prolific. Also, even with no males, the females are almost always sure to be pregnant unless they have NEVER been exposed to a male, as females store sperm for long period of time so they can repopulate when no males are present.
Edit: Do not buy female guppies unless you want fry. They are live bearers. Therefore, they are much more prolific. Also, even with no males, the females are almost always sure to be pregnant unless they have NEVER been exposed to a male, as females store sperm for long period of time so they can repopulate when no males are present.