Pictus is certainly an option. I should probably clarify though, I put 40g as the absolute maximum size for a tank I could get. I was honestly hoping for something more in the 15-20g region, or even smaller if possible. One that came to mind was one of the smaller species of bumblebee cats?
Thoirny cats are a bit too big and a bit too ugly. I'll be setting this up in a college apartment, so kind of looking for fish that the ladies might think of as "cute"...