the gouramis alone will over stock the tank(6in each x 4 =24) plus 3 in for each cory and 2 for each oto
6in x 4 = 24
3in x 3 = 9
2in x 2 = 4
=2.3125 in per gal....as for the oto u might be able to squeeze 1 more in so u have a mini school of them= 2.4375 in per gal....not a big difference....just make sure its cleaned regularly