I've been meaning to post this for a little while but haven't had the time. I have 3 corys in my largest tank (and one twig catfish, fish, and snails). One I've had for about 3 years and last month I introduced 2 small corys after others passed away. The 2 newbies, from completely different shops and different types (peppered and San Juan), like to school together and swim around the tank a lot! But my older guy hasn't been social with any other corys in years. Is it just his personality that he doesn't ever want to make friends or come out with the light on?