I noticed the firemouths in the background, do they tend to get along? And how slow of growers?
I've always mixed firemouths and salvinis. This tank is a 6' 150g which helps reduces aggression. But I've never had an overly aggressive salvini. Usually the firemouths and their boisterousness end up doing the bullying. Especially when you have a group. Salvinis are a shyer fish. But if I had a salvini pair defending fry, the firemouths would not stand a chance.
I have also found female salvinis to be much less aggressive than males.