Probbaly a little too full already. Add some kind of dither fish to keep your cichlids more at ease and be ready to start thinning your current stock when problems arise.
Agree
It may appear to not have enough fish at the moment, if they are all juvies now, but......
as adults, I would consider the tank overstocked. Well kept severums get the size of small dinner plates
What you could add now, might be some geographically smallish dither fish like tetras, hatchet fish, or depending on the size of your current cichlids Nanostomus (pencil fish) and cory cats.
These would add movement in different areas of the water column, and help keep the cichlids remain calm, distracted them from harming each other because the territory of a 75 is quite restricted.
Most small dither species have abbreviated life spans (unlike cichlids) and by the time the cichlids out grow the tank, the dithers will have lived full lives and expired, or eaten by the cichlids.
If you want more cichlids, I'd consider a 6 ft tank, over 100 gals.
I keep acaras (Andinoacara coerleopunctatus)and started with a dozen in a 180 gal tank, within about a year, the alpha male had reduced the group to 4, himself and 3 females as an acceptable (to him) tank population.
