I currently breed my ancistris in a 55g tank - 4' long x 1' wide.
Just one breeding pair, and at one point probably over 100 little offspring (multiple ages/sizes).
Right now I'm probably down under 50 one-inch fry.
(I slowed the bristlenose breeding down a bit because some dwarf cichlids in the tank also started breeding)
I found that this tank got pretty crowded as a growout tank for 100-150 fry (pleco and dwarf cichlids) - and got very messy.
Lots of water changes
And that's just from one nice pair of ancistris - 10 pair are going to be hard to keep up with !!!
As to the black ghost - I know when I had a nice sized one (10 inches or so) he used to eat pretty big earthworms and also suck the eyeballs out of platies - I wouldn't have trusted him with baby plecos (and I would have worried that he'd get one "stuck in the throat" trying to swallow it)