Here I have some interesting information. In China there is a line of checkerboard turq that has a pretty decent % of 5th bar (some with both 5th and 6th bar) offspring, and this line has been maintained well for many years just simply by inbreeding. I got a chance to talk to the earlier breeders who "created" this line, and what they told me really surprised me. They have never crossed this line with Heckel nor any other wild discus. They happened to get some fry with the 5th bar in a couple of spawns of a pair of ordinary turqs, and then they bred these 5th bar turqs and this is how this line was created.
Xiaofei