3 Odessas and 4 tigers. And I know you're going to roll your eyes at me, but I have the nicest tiger barbs in the world (He has shared tanks with tigers for well over a year without any incident). The only fins they nip are their own. They spend most of their time swimming around in a mega school with themselves and the 5 clown loaches.
This isn't really fin-nipping though. He has been tormented by a few fish in his day (he's only in this tank to begin with because the fish in the larger tank were picking on him - it was this behavior that made me decide to just turn the big tank into a monster tank and brought me here!) and the results were much different. Tattered fins, etc. But not this clamping/rotting/redness issue I'm seeing now.