I actually just added a con to my tiger barb tank. My father in law had 3 in a tank and 2 of them were picking on the 3rd terribly. I couldn't let them kill it, and the only tank I had room in was my tiger barb tank.
Funnily enough, the barbs "adopted" him and their shoal follows him around like he's their leader.
Its only been a week, but so far so good.