my memory is not perfect but here's part of the article:
L. caeruleus was first identified in 1956 by G. Fryer. He described this fish as normally being white, with a black stripe through the dorsal fin, which would become a pale blue cast in breeding males (probably the morph from Nkhata Bay, Malawi). Believe it or not, this species was named caeruleus (meaning "blue" in Latin) for this very reason. It wasn't until around 1980 that this xanthic color variant was discovered by Stuart Grant and his divers. Grant et. al supposedly discovered a small colony of "Electric Yellows" at Lion's Cove, Malawi.
Stuart Grant only collected a few specimens, but refused to mass-collect and export them because of the population's small numbers, fearing that they would be pushed into extinction. Then two Swedish collectors paying a visit to Stuart Grant noticed these beautiful, bright yellow mbuna in his tanks and requested that he collect and export some for them. The story is that when he declined, these two Swedes bribed some of his divers, who knew right where they were located. They then returned to Sweden with two yellow labs, unbeknownst to Grant
From what I have read, these two yellow labs were then given as a gift to Pierre Brichard, who was very impressed by them. This is where the story gets really interesting: Brichard then took them back to his fishing operation in Burundi, along Lake Tanganyika (of all places!) and bred some 20,000 fish, all related to that pair. Quite amazing. And he did this in less than six years time. Then, in 1986 he made them available to the public, selling them for a hefty price from what I hear. Brichard ended up making a good dollar off that pair, while Stuart Grant on Lake Malawi, who found the fish in the first place, was left holding the bag.
The story of the yellow lab doesn't end here, my friends. When Brichard put his yellow labs on the market in 1986, he called them "Labidochromis tanganicae", which caused immense confusion among hobbyists. Was this a Tanganyikan Labidocrhomis species, or had Brichard collected this "new" Labidochromis from Malawi and raised it in his ponds on Lake Tanganyika? Eventually the issue was settled, but it did cause quite a commotion. And to think, that most yellow labs in the hobby all descended from that single, illicit pair.
Stuart did capture 22 fish later on but had a bit of a spill and only a few were left. These were given to Gary Kratchovil in San Antonio, TX. You'll see him offer F1 stock from time to time. A couple of years ago, a friend of a friend bought some F1 yellow labs that had been pond-raised in Africa. Surprisingly, they were no better in quality than other good yellow labs that we have seen! There are plenty of bad strains out there - some with lots of black on the body and face. There is a morph with a whitish belly that is not as attractive. Don't be mislead into thinking that is a man-made strain. This is a naturally occurring morph that comes from Lion's Cove, along side the yellow lab we all know
link to full article: http://www.cichlidforum.com/articles/l_caeruleus.php