Having stripped about half the biomass out of my plant tank, I became reacquainted with the pygmy corys. I started out with ten in the tank; I'm not certain how many of them survived, but I'd say there's a minimum of nine. When they were first forced out into the open they became very skittish, but they seems to be settling down a little. So the thought of getting them to breed crossed my mind. Unlike Macropodus, I suspect there's a market for these fish - I have only seen them once at local pet stores. While I may not be able to sell them, I suspect I could get the one independent store to trade some.
I googled breeding pygmy corys and got several promising hits. While they all agreed that the fish weren't difficult to breed, they differed markedly with respect to their thoughts on the idea setup. Ian Fuller at Pets Parade ("Britain's Biggest Petshop") says he uses four males and two females for breeding. However, he is writing about all five "pygmy" species in the article (Corydoras cochui, C. gracilis, C. habrosus, C. hastatus, C. pygmaeus and C. xinguensis), so that may not be the place to look for something overly specific.
Writing at AquariumFish.com, Mike Hellweg gives a very detailed description of C. pygmaeus breeding behaviour. He notes that, although they spawn in a group, each male "stakes out" a specific female and breeds only with her. Consequently, he goes for balanced sex ratios in his breeding tanks. On the other extreme, Kaycy Ruffer at PlanetCatfish recommends "at least one female to six males".
There's a wealth of fish keeping advice online, but the problem is that people simply say what works for them. All three of these appear to have successfully spawned pygmy corys. None of them given any indication that they have experiments with different setups, and only Mike Hellweg explains why he made the decisions he made. It's like reading testimonials for "alternative medicine". Sure, people took the product and got result x, y or z. But how do you separate coincidence from successful practice? Therein lies the problem.