Barbel are only 'native' in a few rivers in the UK, those that flow out to the North Sea. This is because the Thames, Trent, etc. were all tributaries to the Rhine 25000 years ago when the sea level was lower. The English Channel did not exist then and the "mega-Rhine" flowed out to the north of what is now Scotland.

All UK barbel in rivers that do not flow out to the present-day North Sea are there as a result of stockings, mostly carried out since the 1950's, i.e. the Angling Times sponsored stocking of the Severn in 1956, but some were carried out by Victorian gentleman anglers. A large number of these stockings have been unofficial, the Ribble barbel population is widely believed to have originated from fish smuggled back from the Severn for example.