I've had my female salvini in a community 110 galon tank for a while no with no issues. Fish in my tank:
Nic (Male): 8"
Nic (Male): 3.5"
Nic (Female): 3"
Cuban (Male): 3.5"
Salvini (Female): 4.5"
Silver Dollars x 3: 3-5"
This is actually a very peacefull tank, the small cuban tries to run it but obviously doesn't try to push around the big nic and salvini. I've had agression problems with most of my salvini, but this female is very mild mannered. I think you just need the right combination and have them together from a very small size.