Tilapia: Miracle Fish (Part 2)

The article “Tilapia - Miracle Fish (Part 1)” explained that “Market opportunities for green growth and special quality tilapia produced using sustainable intensification technologies should be viewed as an opportunity rather than a liability.” These green growth initiatives have been followed up in this article, Tilapia - Miracle Fish (Part 2) - it features an in-depth view in sustainable tilapia farming discussing aquaponic systems, hydraulic water-driven vertical farming systems and cage farming.

The sustainable seafood movement is gaining traction outside of North America and the EU markets in South America, the Middle East, Australasia, South Africa and the greater part of Asia among more formal markets, supermarket multiples and restaurant chains.

A common theme among seafood rating NGOs is the promotion of seafood consumer guides. These typically provide a list of best or recommended choices, best alternatives or lets “think twice”, and lastly an avoid list of fish species and/or sources guiding consumers away from unsustainable seafood choices. The “Seafood Watch Program” in the US and the “Good Fish Guide”, an initiative of the Marine Conservation Society (MCS) in the UK, have in addition embraced a more holistic approach in their seafood rating guides to include food safety and consumer protection, animal welfare and violations of labour standards through third party sustainably produced and responsibly farmed certification(s). The most prominent certification schemes include the Aquaculture Stewardship Council (ASC), Best Aquaculture Practices (BAP) and GLOBALG.A.P. Supplemented by Friend of the Sea add-on labelling.

Globalisation and a wave of negative publicity in the net pen salmon farming sector in Canada and Chile, i.e. stock escapes, habitat damage, water pollution and algal blooms, has spilled over affecting the ratings of tilapia cage farming in the tropics. The Good Fish Guides advisory to consumers in the UK, for instance, is to make sure the tilapia they buy are Aquaculture Stewardship Council (ASC) certified or originate from more sustainable Recirculation Aquaculture Systems (RAS). Sustainably forms the cornerstone of the “Good Fish Guide” guided by production methods which reduce negative environmental impacts (e.g. discharges, escapes, transfer of disease and parasites, habitat damage and water pollution or degradation) associated with other culture systems such as open net pen/cage culture and pond systems.

Similarly, farmed tilapias raised in Recirculation Aquaculture Systems (RAS) worldwide have been ranked “Best Choice” by the Seafood Watch, an initiative of the Monterey Bay Aquarium, which aims to help consumers and businesses make ocean-friendly seafood choices using science-based recommendations.

Conversely, tilapia originating from net pen or cage farms in pristine lakes whether in Indonesia or Guatemala ranks as “Good Alternatives” by the Seafood Watch Program. Although much of the best quality tilapia originates from net pen farming in pristine tropical lakes where the environmental costs are not counted nor passed onto consumers nor recovered by resident lakeshore communities, nor taxed by regulatory authorities.

What is evident is that a well managed cage-farming operation which may acquire BAP or ASC certification subsequently might not score as the best seafood choice by the Good Fish Guide or by Seafood Watch. Clearly, in recent times the globalisation of the sustainability movement has begun to reward more sustainable fish farming operations commanding premiums for greener tilapia derived from more sustainable farming systems.

Viewed either as a liability or opportunity, tilapia producers the world over, need to adapt to capture consumer trust and market share to access more rewarding local and international markets, or alternatively suffer relegation to less rewarding local informal markets in the developing world.

To counter the deleterious environmental effects of aquaculture growth, expected to more than double by 2050 from 2012 production levels, the World Resources Institute (WRI) in 2014 issued a plea for aquaculture development to abide by a set of directives in their report entitled, “Improving productivity and environmental performance of aquaculture”.

Increased investment in technological innovation and transfer, and the promotion of low-impact production systems are among the major themes advocated by WRI who first coined the term sustainable intensification.

Meeting the appeal of discerning local urban markets, and also highly regulated international markets, will increasingly require a shift on the part of producers to embrace “certifiable sustainable intensification” aquaculture systems such as RAS, Biofloc Technology (BFT), aquaponics technologies, Integrated Multi-Tropic Aquaculture (IMTA) and systems which include integration into irrigation schemes. Low impact “sustainable intensification” systems perform well across most indicators of productivity and environmental performance, ease resource constraints and can reduce food-miles given their placement flexibility capability.

Food safety is another concern. Tilapia produced using biosecure RAS at Blue Ridge Aquaculture in Virginia, US and large-scale BFT in Malawi by Chambo Fisheries have shown that it is entirely possible to raise fish without the use of antibiotics or hormones, and free of mercury (undetectable levels) and other industrial pollutants. Green growth opportunities in tilapia aquaculture present exciting opportunities across the globe, several of which are introduced here.

Figure 2: Chemical- and hormone free tilapia reared in Blue Ridge Aquaculture’s RAS in Virginia, US.

The freshwater production of tilapia either using a RAS or BFT system integrated into a decoupled aquaponics system for nutrient recovery offers green growth potential worldwide. This production philosophy enables water conservative chemical free fish and leafy green vegetable production either within or in close proximity to urban markets generating practically zero effluent.

A decoupled aquaponics system enables both the fish rearing and the vegetable production components to operate at their respective optimum water temperatures increasing placement flexibility into temperate climates. The bridge between the RAS or BFT includes an anaerobic digester to enable sludge digestion and mineralisation followed by the use of a Moving Bed Biofilter (MBB) to reduce nitrogenous compounds into usable nitrates and other plant nutrients for the aquaponics component.

Large-scale decoupled RAS aquaponics systems, using rafts, are being developed in South Africa (Figure 3) and elsewhere. Similarly, a collaborative US-Brazilian research effort published in 2017 compared BFT and RAS aquaponics. Results indicated superior leafy green vegetable production using waste streams from BFT over RAS for the production of three varieties of lettuce Lactuca sativa: red lettuce, butter lettuce, and crispy lettuce

Figure 3: Large-scale decoupled raft aquaponics system under development in the Western Cape, South Africa.

Figure 4: The Sky Greens NFT hydraulic water-driven vertical farming system in Singapore offers great promise for urban and peri-urban tilapia aquaponics around the globe.

In the next few years we are likely to see large-scale tilapia production using decoupled hydraulic water-driven vertical aquaponics systems such as those developed by Sky Greens for hydroponically grown fresh produce in Singapore in urban and peri-urban settings. Accelerated urbanisation, particularly in the developing world, will provide a ready market for sustainably produced chemical free tilapia and leafy green vegetables. Chemical free aquaponically grown produce usually attracts premiums in the marketplace offering excellent green growth opportunities for tilapia and vegetable production close to urban centres.

RAS and BFT tilapia production, due to their reduced waste streams and conservative use of freshwater, offers attractive integration opportunities where cropland irrigation is practiced in the tropics and warm arid regions replacing or reducing the use of chemical fertilisers.

Similar approaches to those being developed for decoupled aquaponics systems would allow for the inorganic extractive use of RAS and BFT waste streams via the production of a myriad of irrigated crops. The practice of using water for fish production followed by cropland irrigation has become widespread in arid Middle East countries, such as Egypt and Israel, offering a blueprint for commercial agriculture-aquaculture projects the world over.

Since the late 1980s, Taiwan has almost silently capitalised on the Japanese niche market for sushi-sashimi quality tilapia, one up on first grade exportable freshwater reared tilapia, also known as izumidai. The practice involves the movement of near market ready freshwater reared tilapia into marine net pens where they are finished in seawater for a month or so to improve flavour quality and rid fish of freshwater parasites. Taiwanese farmed izumidai tilapia is a prized product in Japan and commands a premium price which trickles down to good rewards for producers collecting on average US$12.00/kg of fillets over the last 10 years or so.

Apart from the Japanese market, favourable reports have emerged from studies conducted in Puerto Rico where Florida red tilapia, a complex hybrid reared in seawater, were marketed and by exploratory market feedback of sea water farmed hybrid tilapia in Gulf of Panama. Consumers ranked marine cultivated Florida red tilapia highly in terms of taste, texture, freshness and presentation equal to or better than silk snapper, Lutjanus vivanus, a popular marine food fish in Puerto Rico commanding similar market prices.

Work in South Africa on the development of pure breeds of the euryhaline species, Mozambique tilapia, raised in sea water in what is believed to be a project of strategic food security for the country is set to begin in 2018. Mozambique tilapia is indigenous to South African rivers and estuarine waters along the east coast and has shown to be the most salt tolerant of all the tilapia species.

International markets, apart from Japan and more discerning urban markets the world over, have for the most part been deprived of the opportunity to sample best quality sea water farmed tilapia as well as izumidai products for sushi bars. In fact, a second tilapia farming revolution is prognosticated following the development of tilapia breeds capable of performing well in full-strength seawater (35ppt) given their improved flavour quality and marketability. The Centre for Economic and Management of Aquatic Resources (CEMARE) scientists at the University of Portsmouth (UK) speculated that the development of vertically integrated large-scale operations coupled with low production costs at the higher technological end in tilapia culture may lead to the evolution of an industrial concentration similar to that witnessed in farmed Atlantic salmon. This may well prove to be the case in marine cultivated tilapia due to improved flavor and marketability.

The real prize lies in the use of Biofloc Technology (BFT) raising hybrid red tilapia, or Mozambique tilapia, which perform well in sea-water, within a land based IMTA raising valuable organic and inorganic extractive species specifically engineered and purposed for nutrient recovery (Figure 5). In a pioneering effort, work is underway to initiate a land-based BFT-IMTA industry raising Mozambique tilapia in South Africa.

Figure 6: Large-scale industrial BFT tilapia farming in Malawi by Chambo Fisheries.

Figure 7: BFT grow-out tank field at Chambo Fisheries, Malawi.

BFT capitalises on the apt filterfeeding ability of tilapias to recover microbial protein and nutrients via grazing on ‘heterotrophic plankton’ (collectively called biofloc) undoubtedly the perfect ‘miracle’ fish for BFT tank culture. Large-scale BFT tank culture in Malawi of both Mozambique tilapia (Oreochromis mossambicus) and Shiranus tilapia (Oreochromis shiranus) proved the merits of the technology. Results under large-scale commercial conditions were more than satisfactory. Using bioenergetic feeding rate models to establish optimum feeding levels the project realised Feed Conversion Ratios (FCRs) averaging 1:1 feeding a 20.2 percent protein ration which approximates Carbon: Nitrogen Ratios of 15.5:1 required to ensure a largely heterotrophic community dominance of the ammonia immobilisation pathway in BFT systems.

Table 1 illustrates the advantage of biofloc raised tilapia at Chambo Fisheries achieving impressive performance metrics notably 36.6 percent Net Protein Retention (NPR) and 20.9 percent Net Energy Retention (NER) on an edible meat yield basis. Biofloc tilapia production is then over 100 percent more efficient when gauged against Net Protein Retention (NPR) values of tilapia raised in a RAS system and 162 percent more efficient than lake cage culture as reported in Table 1.

Table 1: Product yield, energy and protein retention in edible parts of Atlantic salmon, tilapia, pigs, chickens and lamb

a Harvest yield is yield of gutted and blend animal
b Edible yield is ratio of total body weight that is normally eaten, muscle, body adipose tissue and liver, lung, and heart for pig Skin is excluded from all animals except in tilapia where skin has been counted. Harvest and edible yields for tilapia based upon the work of El-Zaeem et al. 2012 determined for 125 to 185g tilapia
c FCR = (kg feed fed)/ (kg body weight gain)
d Net Energy retention = (energy in edible parts)/ (gross energy fed) for all animals except tilapia taken at whole carcass energy content from Lupatsch (2012)
e Net Protein retention = (kg protein in edible parts)/ (kg protein fed) for all animals except tilapia taken at whole carcass protein content from Lupatsch (2012)
f FCR data based upon results achieved at Chambo Fisheries feeding 20.2% protein feed (C/N ratio = 15.5:1) feeding 127g to 147g Oreochromis shiranus
g FCR data from Chowdury eta al. (2013) feeding a 32% protein feed, GE of 16.7MJ/kg, DE of 14.3 MJ/Kg raising fish up to 220g
h FCR data based upon achievements in large scale cage culture raising 127/147g Nile tilapia (O. niloticus) on 32% protein extruded feeds
i FCR, edible meat yield, energy and protein retention as percentages of edible meat yield in beef taken from Smil (2002)
j Calculated from Diana et al. (1994). Supplemental Feeding of Tilapia in Fertilized Ponds. JOURNAL OF THE WORLD AQUACULTURE SOCIETY Vol. 25, No. 4 December. 1994.

Data from:

1) Bjorkli, J. (2002. Protein and energy account in salmon, chicken pig and lamb. M.Sc. Thesis, Norwegian University of Life Sciences (UMB), Norway for Atlantic salmon, pigs, broiler chickens amd lamb.
2) El-Zaeem et al. (2012) Flesh quality differentiation of wild and cultured Nile tilapia (Oreochromis niloticus) populations. African Journal of Biotechnology Vol. 11(17), pp. 4086-4089.
3) Smil,V. 2002. Nitrogen and Food Production: Proteins for Human Diets. Ambio Vol. 31 No. 2, March 2002
4) Unpublished inventory data from Chambo Fisheries (historical data in archives)
5) Diana et al. (1994). Supplemental Feeding of Tilapia in Fertilized Ponds. JOURNAL OF THE WORLD AQUACULTURE SOCIETY Vol. 25, No. 4 December. 1994.

These results would suggest that properly managed biofloc tank culture of tilapias is potentially the most efficient form of feedlot livestock production. It outperforms lamb, broiler chickens, pigs and beef steers as well as feedlot aquaculture systems raising Atlantic salmon in net-pens, and tilapia under typical lake cage culture, greenwater pond farming and RAS conditions in terms of protein recovery on an edible yield basis.

A comprehensive economic study based upon data gathered from Chambo Fisheries shows BFT farms at a scale of 800 tonnes per annum to potentially deliver significant production cost advantages. The farm gate production cost advantage of a BFT Shiranus tilapia farm over the large-scale lake cage culture operation, greenwater pond farm and RAS farm was 61.2 percent, 11.3 percent and 35.4 percent respectively.

Marine BFT raising Mozambique tilapia is seen as a strategic move to secure additional whitefish for the South African market to replace national supply shortfalls of Cape hake comprising two species, Merluccius capenis and Merluccius paradoxus. The Cape Hake fishery has been capped by quotas of around 150,000 tonnes in recent years, leading to national supply shortfalls requiring increasing deficits to originate from the adjacent Namibian Cape hake fishery. South African consumers have a bias toward marine fish where it is anticipated that the improved quality and image of more affordable marine cultivated tilapia will meet required flavour (free of flavour taints) expectations in the South African market place.

Marine BFT promises to revolutionise tilapia aquaculture industries globally. In fact, leading scientists believe that harnessing the flow of microbes to fish represents the next revolution in food production. Resource use efficient BFT represents a game changing technology which greatly shifts economic factors in the favour of producers, enabling reasonable profit margins in tilapia aquaculture, given typically less than desirable fish selling prices in more mature markets.

The combined productivity, economic and sustainability benefits of marine BFT, using a land-based IMTA approach coupled with improved flavour quality and marketability, offer intrepid and pioneering marine tilapia farmers in South Africa and elsewhere a pot of gold at the end of the rainbow.

Shifting market perceptions favouring sustainably and responsibly farmed seafood, not only in the North American and EU market, but also across the world due to globalisation of the sustainable seafood movement offers green growth opportunities for the tilapia sector.

Viewed either as a liability or opportunity, tilapia producers the world over require to adapt to capture consumer trust and market share to access more rewarding local and international markets for certified produce, or alternatively, suffer relegation to less rewarding local informal markets in the developing world.

Leading seafood rating NGOs the “Good Fish Guide and Seafood Watch” have rewarded more sustainable RAS tilapia farming operations with a “Best Choice” rating paving the way for premiums for greener tilapia derived from more sustainable farming systems. This was the needed ticket for green growth technologies such as RAS, BFT, IMTA, integrated tilapia farming and aquaponics operations to capture market share by distinguishing their superior quality produce and standards of higher food safety through branding and certifications in both more discerning local and international markets.

The author of this submission predicts that a second tilapia farming revolution will follow the development of tilapia breeds which perform well in seawater due to improved flavour properties and, therefore, market appeal of marine cultivated tilapia. Work has begun in South Africa to develop O. mossambicus for marine cultivation using BFT within an IMTA system to achieve zero-effluent discharge and, therefore, aims to set the bar for other aquaculture projects to aspire towards lending more credibility to sustainably and responsibly farmed certifications.

Green growth opportunities to capture consumer trust and market share to access more rewarding local and international markets exist in every country where tilapia farming is developing. Producers who go the extra mile, it seems, will not only be rewarded with premiums for their higher quality and safer produce, but will also demonstrate the pathway to a sustainable food future for humanity.