Those are my favorite kind of cory cat, but they are very expensive here. They also get quite large. I hope you can get a larger tank and more of them soon!
they are cheap here, don't remember how much, too long ago. I had him with some panda cory's a while ago, but i had a tragic fungal infection and his friends died. Him and a zebra danio were all that survived.
Those things are more likely to happen in crowded tanks. That cory must be very hardy as they are generally very sensitive to water conditions. Be sure, when you get a larger tank, to start the cycle with all the stuff from the smaller tank so he doesn't have to go through large ammonia and nitrite spikes.
I wish I could trade him, i feel so bad for him. But I don't know anyone locally that has a tank like 'us'. He's atleast 3-4 years old, so maybe nature wil work, that sounds bad. He doesn't act stressed to be alone (although they don't like to be). He hangs out with the snails hehe.
They can live for 10-20 years, and I hope he manages to. If you have room for a larger tank, you can probably get one fairly cheap if you look at used ones. Most larger cities have on-line classifieds and the one near me is full of good deals on tanks of all sizes.