I don't really know, but as mentioned, I've heard stories of some of the more ancient cories living 'til 20. Probably more like 11-15 in god conditions, maybe longer if they're **~ideal~**
I also have 2 emerald corys that have benn in a 10gal. and then moved to a 55gal and have lived at least 16yrs so far, and I just got 2 more young ones! They are very hardy fish!My sweet emerald cory, Snuffleuppagus, is somewhere in the neighborhood of 22 years old. We know this because we got him within 2 years of our 24 year old iridescent shark, Jaws, also his tank mate. We have made mistakes in these many years of fishkeeping, he is with others of different species, but not his own for example, and the tank is not large enough at 55 gal. to accommodate more fish at this point (his adopted siblings are huge.) But we try our hardest to keep things clean, feed them well and nutritiously, and let them know they are loved. It seems to be working. Most fish, if they survive past the acclimation stage from the store, live in the neighborhood of 11 years with us. I wanted to post this not only because I'm proud of my babies, but also to say sometimes doing your best with what you have can be enough. We don't all have the funds or room (or floor load capacity) for 300 gallon tanks I'm afraid.