Back in the 1970,s when Warrington Anglers used to stock the Bridgewater canal regularly with imported Roach and Bream from the continent one batch circa 1973 was contaminated by European Brown Bullhead Catfish. I know because friends and I caught several around the Dunham and Lymm areas for a few years. These fish were smoothed skinned with prominent whiskers the fish were only small no bigger than 4 oz and they seemed to have vanished several years later, however on a carping session at Agden in the mid 80,s a friend caught one of around 2lb which was over 18 inches long. It is quite possible that these fish have survived and spawned and the fish you caught was a descendant of this initial unintended stocking.
TF_LolB.
