For South African "eco-capitalist" Jason Drew, that's just the first step in a much bigger ambition - to replace the global use of fishmeal as animal feed with maggots, a virtually unlimited renewable resource.

Mr Drew, in Australia this week to attend the Asian Innovation conference, has done the maths, and the sums are compelling.

Each year about a third of the global fish catch is ground up to make about 6-7 million tonnes of fishmeal. About two-thirds of fishmeal is used in aquaculture and the remainder fed to livestock like chickens and pigs, or made into pet food.

About 85 per cent of global fish stocks are now being fished to their limit, or are already overexploited. Using fish to make chicken is becoming environmentally untenable, and in future may be impossible.

Enter the fly, a creature whose reproductive capacity is uncomfortably familiar to Australian farmers.

"While we have industrialised the production of our chickens and farmed fish, we did not industrialise the production of their natural animal protein - flies and their larvae," Mr Drew said.

"Instead we have overfished our seas to produce fishmeal for use in industrial agriculture."

Mr Drew's business, AgriProtein, is using abattoir waste to feed fly larvae, with plans to branch out into vegetative waste and eventually, human faeces.

Female flies can produce 600-1250 eggs in their short lifetimes. AgriProtein is looking to improve on this through an elite fly selection program.

Around 1.5-2 tonnes of blood can feed to production of 420 kilograms of maggots in 72 hours - a handy return on what is now a waste product.

Mr Drew is setting up a factory in South Africa which, when it is commissioned next year, has a planned output of 100 tonnes of maggots a day.

This will be dried down to 26 tonnes of animal feed that will be sold under the name Magmeal. In an analysis of the 18 key amino acids, Magmeal sits "within a few percentage points" of fishmeal in nutritional value, according to Mr Drew.

As AgriProtein grows, it will use different flies for different forms of waste. For blood, the house fly family. For meatier "carcase crush", blowflies; and for vegetative waste, the black soldier fly.

Residue from maggot production on carcase crush or vegetative waste - there is nothing left of blood - can be used as compost.

For anyone squeamish about Magmeal's origins, Mr Drew points out that a wild-caught freshwater fish has probably eaten its share of larvae, as has any genuinely free-range chicken.

Mr Drew had his epiphany about maggots as a replacement for fishmeal in 2008, while standing near a pool of blood behind a chicken abattoir at Worcester, on South Africa's Western Cape.

From there, he and his team have done a considerable amount of learning about how to harness the fly's reproductive cycle in an industrial system.

They learned that flies, which have a powerful need for moisture, drown with ease. Not just in the buckets of water they initially placed in the fly cages, but because they are hygroscopic - able to attract water molecules from the environment - they can even drown on a wet towel.

They eventually solved the problem by floating polystyrene packing balls on water.

Their testing has included 1000 chicken trials on measurements like weight gain and food preferences. "Not surprisingly, nine out of 10 chickens preferred larvae," Mr Drew said.

The Magmeal plant being built near Capetown will be the only plant operated by AgriProtein, and will be largely run as a research facility.

The larvae-producing technology will be licenced out to whoever wants to harness the abilities of what Mr Drew calls "nature's recycler". He said he has had expressions of interest from more than 30 countries.

Mr Drew's immersion in flies prompted him to write a book, The Story Of The Fly And How It Could Save The World.

Flies as saviours, rather than pests, have a long and illustrious history going back to Genghis Khan, he found. The Mongol leader wouldn’t leave home without a box of flies because their maggots were the ultimate wound-cleaner in pre-antibiotic days.