I aggree with the guys.
One O will be enough bioload with the 2 plecos, especially if you give them all the love they need...food that is!
Your tank will seem smaller in no time, once your oscar grows into his environment.
btw I'd love to see some pictures of the plecos!
Pseudacanthicus have my special interrest and are my favorite plecos.
They grow slow but will become BIG eventually.
How long have you had yours?
My pleco-dealer had one specimen that took 12 years to grow to adult size, and he had him for 15 years after that...
Keeping a fish for 27 years is an incredible job, if you ask me.
One day, maybe...