I have 11 pygmy corys, They tend to live in and under the plants rather than on the substrate at the front, They are quite shy. Lovely little fish tho, mine often look like a flock of birds sitting on the leaves of the stem plants. I'm hoping to increase numbers soon.
I love these - I had 6 in my PFK cube, they then bred, died etc, and from the 6 originals I have 7 in my 15-gallon.
I do think they prefer larger numbers though - they tend to be a bit nervous for me and often hide, but in a larger group they should fare better. To the extent that if I'm passing the LFS anytime (a 40 miles round trip for me to get to a decent LFS) I will get another 5 or 6. They behave much like their larger relatives