Columbian Tetras (South American) are a larger size tetra, yet don't get too big, a nice school of 8 or more looks fantastic, beautiful blue shimmer to the body with red finnage, once mature their colour is fantastic!
I keep my 4 Dumerilli Angels with our Discus, till fish shed complete. However, the Dumerilli are very placid, aren't aggressive like Scalare I have found. Some people have had great success keeping angels with Discus (healthy of course) and yet others don't like the idea. I agree with sharn, Discus can pack some punch, mine can be devils :lol: