It would overstock the 75g in my opinion. The aggression level would be outrageously bad, more than likely resulting in the death of most of the fish. If you got baby oscars, jds, and parrots the pictus would pick them off as they "slept" at night, if it is large enough.
I would leave the numbers to 2 oscars, 2-4 bristlenose plecostomus (they stay under 8 inches), and the pictus.
The oscars will pick on the bristlenose if they are small enough, so you may want to get the biggest bristlenose(s) you can find rather than going with babies of them, unless you were to put baby BN in 6 months or so before the oscars.
It is so refreshing to see someone do their research BEFORE buying the fish! Thank you!
