Wild caught can reach 80-90cm IN THE WILD.
Don't expect that in home aquaria.
But expect above 60cm if given a large tank, and healthy diet.
As for captive bred keeping their colors, right now there are two "breeds" of PBB.
Kamihata was the first (and best), and recently Indonesian breeds have hit the market.
These Indo breeds are SUPPOSEDLY bred from a wild caught Chad PBB mother and a captive bred Turkana PBB father (from a bunch of 12 Kamihata CB Turkana produced a many years ago)
Almost all the Indo ones are born with defective fin lets, most very bent.
The bigger fish stores here such as Big-In, Aqua-Art, Polyone and I think redden, refuse to sell the Indo breeds as there is talk of the mother fish actually being a Lapradei and not a PBB.
Looking at some of the juveniles, I can see this too.
Of the Kamihata breeds, they all come with a certificate, and there is 2 types.
Standard Kamihata come with a black cert, and "Premium" come with a white and red cert, and is numbered on the back with a signature at the bottom.
The "Premium" PBB usually come with 17-18+ fin lets, and seem to retain their colors much more.
There was a bunch of captive bred Turkana bred by Kamihata before, 12 hit the market. Never been bred since.
Troubles in the Ethiopian side of the Lake Turkana plus UN sanctions on fishing in the area (along with pretty dangerous wildlife, and even more dangerous rebels) have put a halt on any WC Turkana coming out of there.
I payed a stupid amount for a WC Turkana a while back from Kamihata's "Expedi Kenya" trip, and to be honest, there was not much difference between that and my WC Chad PBB.
If anyone wishes to buy this piece (one of only a handful outside Ethiopia) I sold it on to Aqua-Art, and I think it is still for sale there. Just expect to pay a crazy amount of money for it.