I have both otos and corys in my community tank and both seem to live seperate lives.
Corys are all down in ht ebottom snarfling in the substrate, while the otos are hanging on a leaf on on the tank glass snarfling algea.
Have six of both, but very seldom do I see all at one time. Corys I can spot if I do a diligent search( they hide/live way down in the roots and such), otos are so small and also hide in the plants a lot.
Only reason I'm normally sure of their numbers (besides thats how many I've bought!) is when i tore down the tank a month ago to make room for the new/used 55, thats what the census was. At that time, also found some fish I thought I'd lost!
Neat fish!