The mainichi reports that the feed was created by a team at the South Ehime Fisheries Research Center of Ehime University, and researchers hope to have it on the market in two to three years.

A drop in stocks of fish used to make fish meal and expanding fish farming in countries like China and Viet Nam has pushed the price of fish meal to 200 yen per kilogram or around twice what it was five years ago.

The researchers cut back the fish content of the feed by 25 per cent, replacing a fourth of that with ground fly pupae. The rest was replaced with other ingredients. When the feed was given to sea bream, they showed improved colouring and resistance to disease.

The fly pupae are raised in pig dung by a company in Miyazaki Prefecture, after which they are ground up and pasteurised.

Professor Takeshi Miura, who worked on the research, estimates that at 74.5 yen, the new feed is 5.5 yen per kilogram cheaper than current feeds. "Aquaculture is increasing around the world, but in Japan it is declining, and some businesses have been forced to close. I hope that with efficiently grown feed, we can improve the situation," he told The mainichi.