Paul's off to Aragon in northern Spain, halfway between Saragossa and Barcelona. He meets up with Martin Walker, who has pioneered fishing for Catfish in these parts. Martin takes Paul to the mighty River Ebro, a huge piece of water containing a large variety of fish, including the European Catfish, which can grow to over one hundred pounds in this river. It is here, in Catfish country, that Paul is introduced to clonking.