It doesn't matter how much they see each other, it matters how many of them are in a group. 4 pygmy cories in a 10 gallon won't be any happier than 4 pygmy cories in a 50 gallon tank.Okay the only ones that really matter are the ones with the Bettas. The ones that interest me are #1-4 modified to have a Betta. I think 4 Pygmy Cories would do okay in a 10 gal considering they'll see each other more often compared to 4 in a 30gal. But I could have 1 Betta, 5 Venezuelan Pygmy Cories (Salt and Pepper Cories) and 3 Endlers. That seems like a nice stocking with fish on the Top, Middle and Bottom.
a lot of pygmy cories swim on all levels of the tank, not just the bottom.