Looks like I’ve made a mistake Ron, so much for a Masters in Ecology? There are two species of Black Bass Large Mouth Black Bass (micropterus salmoides and Small Mouth Black Bass (Micropterrus dollomieu), which of these was found in British waters?
Interestingly the Bullhead belongs to the same order as Blenny and Goby, in which there are Siberian and four horned species, while roach and barbel species vary immensely across Europe and your polish barbell could have been a different fish than the English ones, we have barbus plebjus valenciennes (Italian), barbus meridionalis risso (Southern), barbus comiza steindachachner (Iberian) and barbus meridionalis petenyi (Semling), interesting stuff eh?
This is according to Muus Bent J & Dahlstrom Preben (1971)The Freshwater Fishes of Britain and Europe, more speciation has probably occurred since then though?