I don't think It was me who mentioned or suggested that 'big and greedy' barbel are the result of brain damage. Check who said that! My point was that some observed recognised barbel were once upon a time quite elusive to capture; but once they are caught, then some seem to be re-captured more frequently showing no or less sense of caution as before. As we have found, there are seemingly no scientific research papers relating specifically to barbel, only suggestions, personal experiences etc. However, if you search, there is scientific some stuff that relates to other species mentioning effects of being out of the water. As most knowledgeable barbel anglers know already, the longer barbel are kept out of the water, the longer they take to recover when returned. It’s the anglers that don’t know this or care that are the barbel's problem. Just because it is returned to the water and swims off does not mean it survives in the long term. You only need to go to some very popular barbel fisheries, especially in summer, to sometimes see a number of dead barbel, on or under the surface weed, etc. or floating down in front of you, dead, or belly up/side on gasping in air.