It is feeding time at the tank in East London. The shoal of young kabeljou swoops on their food, chasing down sinking pellets with their mouths wide open. The fish, the food and the water they live in are all scientifically managed. A UK website traces where the food eaten by each batch of fish came from. The Espadon Marine grow-out technicians monitor the fish, destined for plates in seafood restaurants, round the clock. Contented kabeljou put on weight, converting fish feed into fillets with a profit margin.

Kabeljou, also known as dusky kob, is favoured by seafood chefs the world over for its texture and mild taste. The Australians call the fish `mulloway’, Americans and Mauritians say `red drum’ for its feline purr when caught. It is called `meagra’ in the Mediterrean and `suzuki’ in Japan. In South Africa, wild-caught kabeljou is threatened, according to the Southern African Sustainable Seafood Initiative (SASSI) and the World Wildlife Fund (WWF). A land-based, water-recirculating kabeljou farm like Espadon Marine gets a green SASSI nod, however.