Sustainable Fish Feed derived from Urban Waste Streams

Project: AquaFeeds in a circular economy: Creating sustainable aquafeeds from urban waste-streams for urban aquaponic farming.

At Bristol Fish Project we are interested in circular economics – we think that waste from one process can be integrated as feed for another. Cities make a lot of waste. A lot of resources come from all around the world to end their lives in cities. This is particularly challenging in the area of phosphates and other finite or close-to-finite resources essential to food production, because it means here in our cities is where they get ‘flushed’ away or buried in landfill, and we can’t easily get them back again.   We need solutions to make these precious resources go further, and to recycle them when they have finished being useful in their current form. This has always been at the heart of our mission – to create an urban intervention that helps to close material loops and bring people closer together around food.

So three things are happening at the same time, that have influenced our desire to start this particular piece of research:

  1. Fish is becoming an important source of protein for people around the world. Fish farming, will soon surpass wild-capture fisheries as the dominant source of seafood (FAO, 2010). Farming of salmon and trout is the most significant economically in the EU. Globally the top spot is held by Tilapia – the most farmed fish and one we’ve undertaken pilots with. The main issues here are that the key ingredient in commercial fishmeal for aquaculture diets is (increasingly scarce) wild-caught fish.
  2. It’s all very well to do more fish farming, but the waste streams from fish farming can be bad for the environment
  3. In Europe vast quantities of food is wasted at the point of food processing – a phenomenal loss of energy and increasingly scarce nutrients like phosphate that are both valuable and essential to horticulture and aquaculture.

So what we are saying is that we think we can approach all three of these challenges in this one project. We are going to examine and put into practice opportunities to close material loops and turn commercial food waste into feed and responds to a call to increase food production sustainability whilst reducing waste in the food supply chain and limiting environmental impacts.

We already have undertaken research using the effluents from fish farming to produce edible plants via aquaponics. In this project we want to take the next step in our vision for an urban integrated farm, and look at single-issue solid commercial food wastes that issue from Bristol (for example spent brewery grain) and see if we can integrate these waste streams into our farm.  This allows us to redesign (an albeit small) part of the food processing chain in Bristol, closing material loops to improve resource efficiency.

Context of research question – can we create a fish feed based on locally available waste-streams and move away from dependency on unsustainable wild-caught fish-meal?

Research question for this pilot:

What can be the role of black soldier fly in the creation of a fish feed made from locally derived waste streams?

In this research we are using Black Soldier Fly – Hermetia illucens (a common fly of the family Stratiomyidae) in the larval phase to compost a diverse range of local food waste streams and generate with the prepupae a resource-efficient and high nutrient wild-catch fishmeal substitute that could have a significant beneficial economic and environmental impacts.

Black Soldier Fly Larvae (BSFL) as a feed have been trialled extensively on the small scale for over 30 years, and are found to be a compelling potential commercial feedstuff for other food-animals. When dried (for easy storage) the prepupae (BSFP) contain 42% protein and 35% fat. In combination with other ingredients, BSFP have been trialled successfully as a feed for rainbow trout and catfish achieving good growth and health results. Studies indicate that BSFP can replace >25% of a fish meal in a diet with no negative effect on growth in rainbow trout and in channel catfish. The fat content of the BSFP is the main challenge to increasing its concentration in a feed mix – however separating out the BSFP fat could allow for feed with 60% protein. The removal of chitin could enhance the digestibility of the feed and provide and additional value added product from commercial food waste.

Food safety and bacterial considerations for using this feed are so far favorable. In China, the USSR, USA, Mexico and Eastern Europe BSFP have been fed to poultry, pigs, shrimp, various species of fish, turtles and frogs. No adverse impacts have been recorded. Moreover anti-microbial factors were recorded reducing the chance of feed transmitting pathogens wherein BSFL have been shown to significantly reduced E. coli 0157:H7 and Salmonella enterica in hen manure.  The safety and traceability of this feed must be rigorously investigated during this project, but this does not detract from our view that the large-scale production this feed would absorb vast quantities of commercial food waste whilst also reducing other agricultural and environmental problems.

The Facility

We have set up a temperature controlled greenhouse within our farm.

Inside we introduced 9 vats (Ikea Sortera) so we can test 9 substances, or in the case of this research, 3 substances, 3 times (triplicate test).

We referred to The University of Stirling’s guide for raising Black Soldier Fly to establish the growing conditions for our research.


The Urban Waste Streams tested:

We found the following waste streams to be readily available:

  • Coffee Grounds from cafes
  • fruit and veg waste and scraps from greengrocers (but also prospectively food processing)
  • Waste bread from bakeries
  • Waste grain and lees from breweries


TEST 1 (Baptiste Grollier, Alice-Marie Archer, Sam Rossiter) October – December 2017.

Testing array:

A1-3 Spent Grain | B1-3 Waste Bread | C1-3 GreenGrocer Waste

Stacked 3 vats high under the worktop.

Heater with thermostat set at 30 degrees.

We also considered, how will we measure performance?

  • By wet weight?
  • By mass spectrometry with assistance from the university?
  • By weight of food-waste consumed?

And decided to go with wet weight of grubs, weighed in batches of 30 with the average of their weight recorded, at intervals.

We bought ~250 * 9 packs of tiny larvae from a stockist, and fed them the 3 feeds to see which test vat had the fastest growing grubs in it.


Average Weights of larvae / pupae after 20 days:

Spent Grain: A1 (top) 2.684g | A2 (middle) 2.021g | A3 (bottom) 2.244g

Waste Bread: B1 (top) – 3.10g | B2 (middle)  1.467g |B3 (bottom) – 2.157g

Green Grocer Waste: C1 (top) – 2.011g | C2 (middle) – 1.838g | C3 (bottom)  -1.743g


Difference in size increasing from bottom to top thought to be due to temperature stacking effects.

Although bread provided the largest grubs in the top vat (and the smallest in the middle vat?). It was considered to be undesirable to handle. Many colours of mould and fungus grew in the vat and the operative was keen to avoid breathing spores. Also seemed undesirable to have spores in the air on the farm in general.

Veg waste from the green grocer was the hardest and messiest to handle in terms of preparation and labour intensivity. It also left the greatest waste, which was sloppy, sticking and according to Beca Beeby’s at Humble by Nature research likely caustic.

It was apparent that in this test, spent grain from brewing provides the easiest to handle and an accessible waste=feed input for this research.

Conclusions / Decisions

We determine that we want to look more closely at spent grain – and test a full life cycle on rotation.

We also need to get our flies to reproduce and place eggs so this needs to be perfected.

We need to examine more closely how black soldier fly larvae might be blended with other ingredients to create a balanced feed for our eels.

We continue to examine our research questions:

How does this research fit with the wider context for the research (can we create a fish feed based on locally available waste-streams and move away from dependency on unsustainable wild-caught fish-meal?) – i.e. what part of a whole feed can this represent?

  • How is this different for different species?


How might this research be transferable to other cities?

What are the challenges with creating feeds from Black Soldier Flies?

What is the opportunity does the integration of urban waste into feeds represent for the sector?

Trial 2 begins in February 2018.


Newton, G. L., C. V. Booram, R. W. Barker, and O. M. Hale. 1977. Dried Hermetia illucens larvae meal as a supplement for swine. J. Anim. Sci. 44:395-399.

St-Hilaire, S., K. Cranfill, M. A. McGuire, E. E. Mosley, J. K. Tomberlin, L. Newton, W. Sealey, C. Sheppard, and S. Irvin. 2007b. Fish ofal recycling by the black soldier fly produces a foodstuff high in Omega-3 fatty acids. J. World Aquaculture Soc. 38:309-313.

Newton, L., C. Sheppard, W. Watson, G. Burtle, and R. Dove. 2004. Using the black soldier fly, Hermetia illucens, as a value-added tool for the management of swine manure. Univ. Of Georgia, College of Agric. & Environ. Sci., Dept. Of Anim. & Dairy Sci. Annual Report.

St-Hilaire, S., C. Sheppard, J. K. Tomberlin, S. Irving, L. Newton, M. A. McGuire, E. E. Mosley, R. W. Hardy and W. Sealey. 2007a. Fly prepupae as a feedstuff for rainbow trout, Oncorhynchus mykiss. J. World Aquaculture Soc. 38:59-67.

Newton, L., C. Sheppard, W. Watson, G. Burtle, and R. Dove. 2004. Using the black soldier fly, Hermetia illucens, as a value-added tool for the management of swine manure. Univ. Of Georgia, College of Agric. & Environ. Sci., Dept. Of Anim. & Dairy Sci. Annual Report.

“Research Summary: Black Soldier Fly Prepupae – A Compelling Alternative to Fish Meal and Fish Oil”

Erickson, M. C., M. Islam, C. Sheppard, J. Liao, and M. P. Doyle. 2004. Reduction of Escherichia coli 0157:H7 and Salmonella enterica serovar Enteritidis in chicken manure by larvae of the black soldier fly. J. Food Protection. 67:685-690.

University of Stirling How-To-Guide