The Pandas are especially delicate fish, for some insane reason, and are really sensitive to not only water quality but water quality changes. We had three Pandas kick within two days a few months back, after they'd been in the tank for well over a month. Nothing changed, and the water chemistry was all good (though the pH was around 7.5). It looked like they basically starved, as they spent most of their time hiding. OTOH, the remaining three Pandas have always been more active and social and have eaten like pigs, and are still doing well. They shoal with the Corydoras julii, and one Panda in particular seems to have a major crush on one of the Julies.
The Peppered Corys (Corydoras paleatus) do a lot better in much cooler water, according to the Big Boys and Girls Who Know More Than I. They want a top temp of 24C, or they get really stressed. Seems a bit weird for such substantial-looking fish, but they apparently over-rev and basically burn themselves out in warmer water. I saw this info in three separate sources, so guess it may have some credence. That's the only reason I don't have any, and went with the C. julii instead.
Good luck, and if you're looking for another good small Cory the Julies are tough little cusses. Top out at 55mm, though mine are all more like 45mm.
HTH
Glen