In Europe "US Blue Gularis" are recognized as a strain of SJO much in the same way in the US the German dwarf red strain is recognized.
It's always been true that in the US certain strains are known to have above average size, color and finnage. It would be a rare fish indeed from the wild that lucked out and got genes this a good and was able to grow them fully out.
Yet it is possible, and much more so likely in a fishtank than in the coastal waters of Nigeria or in a small stream in Cameroon. That is, the selective breeding if the US blue strain preserves the best of what a Nigerian SJO can be in a strain that breeds true.
I would not really say it's an artificial tank bred man made creation of something that does not exist in nature, but rather it's a strain, tank bred, to represent the ideal Nigerian SJO.
The names of people in the US involved in this will be familiar to many: Paul Hoppe, Mikkelson, Bob Schwiegerath, Mike Epperson, Rosario LaCorte.