Will my tank be Overstocked?

Uhhh...I think the fish will be okay with one or two more fish, as I have 5 parrot cichlids (which I'm trying to tell my dad that need to be upgraded soon as the biggest dominant male is bullying the other fish for food...) in a 55 gallon, and the biggest one is at LEAST 8 inches long (had most of the cichlids for 15 years, before I was born, as I'm only 13 now...)