Having calculated roughly that the pike measured about 1m (3.2ft) long and the zander about 75cm (2ft 5in), with a combined weight of about 15 kilos (33lb), he threw them back in the water.
Though intended only for the morbidly obese (those with 45 kilos or more of excess weight), the surgery is attracting the attention of thinner patients who want a quick fix.