Ok, thanks for that, the reason I was asking this question was because of a wrong line of thinking on my part.
Many years ago the River Rother in East Sussex was twice stocked with Barbel. I was only told this but, I believe they were quite substantial stockings (I like a substantial stocking myself, pardon me, a Christmas one that is !). They were never seen again as far as I know, no one has ever caught one. This did not surprise me really as I thought the river is unsuitable for Barbel but, then I was thinking it is a good Chub river( I believe it held the record once). So, I was reasoning that as it seems on many rivers Chub and Barbel coexist very well on many rivers, if its good for Chub, why not Barbel.
However, I can see that Chub are far more catholic in there requirements whereas Barbel are a lot more particular so, it would not hold that just because a river is a good Chub river it does not mean it would also be a good for Barbel.
Mind you I do wonder if those Barbel have survived somewhere. A lot of this river does not get fished much in the out of way places but, it is predominately silty.
Cheers and a Happy Christmas to all members, past and present.