Fish is already a major source of protein and other nutrients for millions of people. With rising demand putting pressure on global supply, aquaculture and farmed fish are increasingly seen as the answer. As the world population expands and fish stocks decline, the world is turning to science to explore ways of improving the supply of food for resource-poor people. In the Philippines, genetically improved farmed tilapia (GIFT) have been introduced to increase the productivity of the fish industry.
The various species of tilapia have been of major importance in the fisheries of their native lands, in Western Asia and Africa. In terms of human nutrition, tilapia has long been recognised as an important source. But with greater emphasis on fish culture emerging in the twentieth century, tilapia became increasingly valuable to humankind. As early as the 1920s, experiments in tilapia culture were being carried out in Kenya. Tilapia had become an intercontinental traveller by 1939, when naturally propagating stock of Tilapia mossambica, native to the streams of Africa’s east coast, were discovered in Java. They made themselves at home and spread quickly throughout the island. Today it is found in almost every water body on the island, including stagnant ponds and ditches where few other fish can survive. This demonstrates the versatile nature of tilapia.
The Java tilapia was the first member of the genus Tilapia to come to the attention of large numbers of fish farmers and has remained the most widely cultured species. The other two major species are the Nile tilapia (Oreochromis niloticus) and the blue tilapia (Oreochromis aureus). These three species are the most amenable to aquaculture, due to their tolerance of a wide range of temperatures and salinity. During the past half-century fish farmers throughout the tropical and semi-tropical world have begun cultivating tilapia. Today, more than 90 per cent of all commercially farmed tilapia outside Africa are Nile tilapia.
All tilapia species are nest builders; fertilised eggs are guarded in the nest by a brood parent. They are also mouth brooders: after a short mating ritual the female spawns in the nest (about two to four eggs per gram of brood female), the male fertilises the eggs, and the female then holds and incubates the eggs in her mouth (buccal cavity) until they hatch. Fry remain in the female’s mouth through yolk sac absorption and often seek refuge in her mouth for several days after they begin to feed.
Tilapia are shaped much like sunfish (also known as crappie) but can be easily identified by an interrupted lateral line characteristic of the Cichlid family of fishes. They are thin and tall-bodied with long dorsal fins. The forward portion of the dorsal fin is heavily spined. Spines are also found in the pelvic and anal fins. There are usually wide vertical bars down the sides of fry, fingerlings, and sometimes adults.
The main cultured species of tilapia can usually be distinguished by different banding patterns on the caudal (tail) fin. Nile tilapia have strong vertical bands, blue tilapia have interrupted bands, and Mozambique tilapia have weak or no bands on the caudal fin. Male Mozambique tilapia also have upturned snouts. Colour patterns on the body and fins may also distinguish species. Mature male Nile tilapia have grey or pink pigmentation in the throat region, while Mozambique tilapia have a more yellow colouration. However, colour is often an unreliable method of distinguishing tilapia species because environment, state of sexual maturity and food source greatly influence colour intensity.
Tilapia ingest a wide variety of natural food organisms, including plankton, some aquatic macrophytes, planktonic and benthic aquatic invertebrates, larval fish, detritus, and decomposing organic matter. With heavy supplemental feeding, natural food organisms typically account for 30 to 50 per cent of tilapia growth. Tilipia are often considered filter feeders because they can efficiently harvest plankton from the water. In general, tilapia use natural food so efficiently that crops of more than 3000 kilos of fish per hectare (2700 pounds per acre) can be sustained in well-fertilised ponds without supplemental feed. The nutritional value of the natural food supply in ponds is important, even for commercial operations that feed fish intensively.
Optimal water temperature for tilapia growth is about 29 to 31ºC (85 to 88ºF). Growth at this optimal temperature is typically three times greater than at 22ºC (72ºF). Tilapia survive dissolved oxygen (DO) concentrations of less than 0.3 mg per litre, considerably below the tolerance limits for most other cultured fish. Although tilapia can survive low DO concentrations for several hours, tilapia ponds should be managed to maintain DO concentrations above 1 mg/l. Metabolism, growth and disease resistance can be depressed when DO falls below this level for prolonged periods.
Under good growth conditions, fingerlings are cultured in nursery ponds to 20 – 40 grams (1 – 2 ounces) in 5 to 8 weeks and then moved to grow-out ponds. In monosex grow-out ponds, and under good temperature conditions, males generally reach a weight of at least 200 grams (½ pound) in three to four months, 400 grams (1 pound) in five to six months, and 700 grams (1½ pounds) in eight to nine months. To produce a 400-500 gram (1 pound) fish, common practice is to stock 6000 to 8000 males per acre in static water ponds with aeration or 20,000 to 28,000 males per acre where 20 per cent daily water exchange is economically practical. After six months of feeding with good quality feeds, the first pond type can produce 2200 – 3100 kg (5000 – 7000 pounds) per acre. The other pond type can produce 8200 – 9000 kg (18,000 – 20,000 pounds) per acre.
Room for Improvement
Despite the resilient nature of tilapia, farmers in the Philippines have identified the poor growth of the fish as a constraint to aquaculture development. Research by the World Fish Centre identified that the stocks of Nile tilapia available in Asia were of poor genetic quality. According to the research, the farmers wanted a faster growing fish and an adequate supply of good quality seed.
The Nile tilapia was selected for the first efforts to improve the productivity of tilapia aquaculture in the Philippines. A project for the genetic improvement of farmed tilapia (GIFT) was launched to develop methods for producing improved fish breeds, using Nile tilapia as a model species. The project involved the intended beneficiaries (those engaged in aquaculture), advanced research institutions with experience in genetic enhancement research, and local organisations in the Philippines. The result for the World Fish Centre was that it was credited with the development of the first-ever successful breeding programme for tropical fish. In terms of aquaculture development, over a dozen countries have now adopted the same methods. For the farmers that now have access to this breed, they can generate more income to meet their nutrition needs and those of their families.
World Fish Centre
The World Fish Centre conducts research to improve the productivity and policies of national fishing programmes, while protecting the environment and saving biodiversity. This is achieved through research, partnership, capacity building and policy support. The Centre promotes sustainable development and the use of living aquatic resources based on environmentally sound management. The Centre’s programmes aim towards:
- Improved livelihoods of fishing and fish farming households;
- Reduced impact of fishing;
- Protection of the aquatic environment.
Through a process of crossbreeding and selection with African species, the GIFT project bred a strain of Nile tilapia that grows up to 77 per cent faster and has 50 per cent higher survival rate than other strains after six months. Research has also indicated that the GIFT strain is a neutral technology. This means that small, who often do not use enough feed and fertiliser, and larger farmers, who have access to high doses of these inputs, get the same overall benefit from the fish when they adopt the GIFT strain. The new breed captured 25 per cent of the tilapia fingerling market in the Philippines in only its third year of commercial distribution.
The profile of the genetic improvement experiment generated a great deal of interest, formalised through the formation of the International Network on Genetics in Aquaculture (INGA) as a global forum for fish breeding. The network facilitates continuous feedback and flows of information on the performance of the breed in different environments. The network serves as a mechanism for monitoring and reviewing the progress of fish breeding programmes in the various countries.
After six generations of selective breeding, the rights of the fish were handed over to the non-profit organisation GIFT Foundation International Inc. (GFII), which was set up to continue the research, market the fish, and use the revenues to generate further research on tilapia. GFII entered a collaborative programme with the Norwegian company GenoMar ASA. GenoMar then acquired all commercial rights to the GIFT strain and received a copy of all the latest families. Since then, GenoMar has introduced state-of-the-art DNA ‘tagging’ of the fish in their breeding scheme, which enables them to track the select the most successful genetic traits and wean out the less successful. While GenoMar has developed over 14 generations, the World Fish Centre only has access to the 9th generation for scientific research purposes.
GenoMar entered into commercial ventures using their trademark name, GenoMar Supreme Tilapia, in the Philippines, Brazil and China. Although the company is continuing research that began under GFII, the danger is that they are privatising a source of food and income that is needed by many resource-poor people. The World Fish Centre endorses the intellectual property rights policy of the Consultative Group on International Agricultural Research (CGIAR). However, these policies are often criticised for not fully protecting the livelihoods of the resource-poor. As Patrick Mulvany (Head of Policy at ITDG) maintains, “The CGIAR should not be involved in assisting the privatisation of common goods – such as fish stocks – removing them from continues free access by fisherfolk… As a public research body the CGIAR should insist that the products of its research remain in the public domain.”
Access to the genetically improved fish breeds needs to be kept available to the public, to benefit those who need it the most. Otherwise, all the advances made, all the improvements in productivity, will be available only to those who can afford them and the associated inputs such as specialised feed – but this will endanger the livelihoods of the millions of people in countries such as the Philippines who rely on aquaculture. If unconstrained public access to breeds such as the improved tilapia can be maintained, then these livelihoods may continue to flourish.
Gupta, M. V., Acosta, B. O., Dunham, R. and Gardiner, P. R. (2001). “Fish genetics research at ICLARM – The world fish centre”, in Gupta, M. V. and Acosta, B. O. [Eds.] Fish Genetics Research in Member Countries and Institutions of the International Network on Genetics in Aquaculture. ICLARM Conference Process 64. Pp 97-102.
Hardjamulia, A., Sukadi, F., Subagyo, and Gustiano, R. (2001). “Aquaculture genetics research in Indonesia”, in Gupta, M. V. and Acosta, B. O. [Eds.] Fish Genetics Research in Member Countries and Institutions of the International Network on Genetics in Aquaculture. ICLARM Conference Process 64. Pp 51-59.
Popma, T. and Masser, M. (1999). “Tilapia: life history and biology”. SRAC Publication no. 283. Mississippi: Southern Regional Aquaculture Centre.
World Fish Centre www.worldfishcenter.org
Donor and Supporting Organisations
Department for International Development (DFID) www.dfid.gov.uk
World Bank www.worldbank.org
FAO Fisheries Information Centre www.fao.org/fishery/topic/18057
Fisheries Global Information System www.fao.org/fishery/topic/18043
ITDG Technical Briefs answers.practicalaction.org
Other relevant Hands On case studies
Fishy Business – Peru
Small Fry, Big Catch – Thailand