yeah maybe a delhezi, and i think an oscar will work because the only other middle dwelling fish youre gonna put in there are the ctenopomas, and maybe a knifefish.
plecos dont try to eat the slim off of fish, they only do that if they are super starved. many people believe that plecos will just eat the scraps and do not give food to their plecos, which is why the plecos resort to trying to eat the fish slime.