Nobu, the upmarket Japanese restaurant chain, is warning its customers not to eat its bluefin tuna dish because it is endangered, while still serving the fish on its menu. The company, which has two restaurants in Mayfair and 22 worldwide outlets, has added a notice on its menus in the UK saying that its £32 bluefin tuna dish is “environmentally challenged”. It also added a line stating: “Please ask your server for an alternative”. The move follows a five-year campaign against Nobu’s refusal to stop serving bluefin tuna, which is now on the brink of extinction. The publicised fate of bluefin tuna has led other restaurateurs including Gordon Ramsay to withdraw it from his restaurant’s menus.