The gold barb is a sport of the green, (now Barbodes semifasciolatus). When I started, (1960's), the green was a regular, but they drifted out of fashion compared to the gold, ("Schuberti"), which largely replaced them. A good quality green is a great looking fish.
Another fish, Pethia gelius, is also called a gold barb, often with a "dwarf" added, another great fish. It has been bred to present several variations of the ground colour, copper, red, blue I recall, they are all vague variations on the basic fish, upped by marketing twits.
Things were so much easier when barbs were all "Barbus xxxxxx".