New "fishless" feeds could make aquaculture more sustainable


August 7, 2013

Prawns raised on the Novacq fish-free feed additive (Photo: CSIRO)

Prawns raised on the Novacq fish-free feed additive (Photo: CSIRO)

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When it comes to commercial aquaculture, a lot of people have some legitimate concerns – fish farms can introduce antibiotics, anti-algal chemicals and concentrated fish waste into the ocean; escaped fish can upset the local ecological balance; and wild fish still need to be caught in large numbers, as a food source for some species of farmed fish. While there have been recent efforts to address the first two concerns, the fish-in-the-fish-food problem is now being taken on in two different research projects. These are aimed at replacing the fish content in fish feed with more sustainable ingredients.

A diet of microbes for prawns

Traditionally, farmed prawns (or shrimp, depending on where you’re from) have been fed pellets that contain some fish meal and fish oil. These are included mainly to help the animals grow large, and to do so quickly. Scientists at Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO), however, have spent the past 10 years developing a feed additive that does away with those fishy ingredients. The result, known as Novacq, was officially announced at the end of last month.

Novacq contains marine microorganisms that have been bred in captivity, and which have been shown to play a crucial role in prawns’ growth process. In a large-scale field test, the product was mixed with an existing commercial feed (taking the place of the usual fish meal and oil), then used in ponds at an Australian prawn farm. According to CSIRO, the Novacq-consuming black tiger prawns grew an average of 30 percent faster than their regular-food-eating counterparts, plus they were healthier.

CSIRO plans to conduct more tests of the additive, and has licensed the technology to Australia’s Ridley AgriProducts. It is hoped that Novacq will be commercially available within about a year.

Turning meat-eating fish into vegetarians

Fish meal and oil are also used in the pellets eaten by carnivorous fish, such as sea bream and striped bass. Scientists at the University of Maryland Center for Environmental Science, however, have developed an alternative feed that consists entirely of plant-based ingredients.

Instead of fish meal, the experimental new feed includes corn, wheat, and soy. Taking the place of fish oil is a combination of lipids (fatty acids) from algae, amino acid supplements, and soybean or canola oil.

Dr. Allen Place (left) and Dr. Aaron Watson, developers of the vegetarian fish feed (Photo: University of Maryland Center for Environmental Science/Cheryl Nemazie)

Not only have test fish apparently thrived on the feed, but their flesh reportedly has PCB and mercury levels that are 100-fold lower than those found in fish consuming regular pellets containing wild-caught fish. According to co-creator of the feed Dr. Allen Place, this would allow consumers to eat striped bass twice a week, as opposed to the once every two weeks that’s currently recommended.

Sources: CSIRO, University of Maryland Center for Environmental Science's Institute for Marine and Environmental Technology

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

There has also been work on turning waste food into fish feed by allowing houseflies to breed on the food, laying eggs, waiting for the eggs to hatch then feeding the maggots directly to the fish. Sounds pretty much like a win-win situation.


I love the prawn food replacement. It always seemed silly to catch fish to grind up and feed to fish. Why aren't we just eating the caught fish?

But I have to take exception to the grain fed carnivorous fish. Processed grains and canola / soy oil are bad enough for humans, what will that do to the poor fish that should be eating other sea food? I'd have thought seaweed based oils and protein would be better. The problem with soy is much of it is grown using "roundup ready" soy which means farmers pour poison all over their crops and the ground to gain a bigger harvest. Monsanto can protest as much as it likes but that soy potentially comes with a does of roundup in it which goes into the fish and the water and into us. Canola industrially processed using all sorts of dreadful chemicals which end up being poorly disposed of. The clean process can also mask rancid canola oil which is a known carcinogen. Do we want to fee fish these things? Do we want to pour it into our oceans? Do we want to eat the fish fed on these things? Maybe it isn't so bad, but I have a feeling the questions aren't really being asked.


GMO corn? GMO soy? I hope not, then where does the GMO chain go? Right back to the grocer. Back into the belly of humans where it can possibly be proven to be harmful. However if not using GMO, that sounds good!

F Ed Knutson

of course its GMO soy. Something like 97% of soy is GMo based, so its likely if you're eating soy at all you're eating GMO stuff. I lik the idea of using plant based ingredients, but we really need to get off the monoculture kick. We have a variety of plants at our disposal. It isn't necessary to make any 1 do all the work for us.


The only way to be certain of avoiding GMO is to grow food yourself to bad they are outlawing that one community beautification law at a time. Can't let the public "see" desperation or avoidance of the mainstream culture. If they just use industrial hemp seed they could get food biofuel and industrial fiber in one crop instead of these joke crops that are good for only One thing at a time food OR fuel. fish canning waste can provide the food for fish farms and if they pumped the ammonia nitrate ladened water from fish tanks to algae growth tanks they could feed the algae to plankton to feed back to other fish or prawns or harvest algae for bio oil and then feed it into the system.

Joseph Mertens

Good to see that fish aren't fed to other fish. Biomagnification of mercury levels in fish is a real threat to our health. With all the mercury we're pumping in the air from coal, it will eventually fall into our oceans. And not to mention our lungs.

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