SafeFish: Improving tilapia health using bacteriophages to optimize yields

Aquaculture is one of the fastest growing agro sectors in the world. Fish production provides nutritional, commercial, ecological and societal benefits to many countries including Ghana. However, fish health and management has not being fully exploited and understood for sustainable production. Most aquaculture farmers in Ghana are purported to have fish mortality as high as 75-85 percent after stocking with fingerlings (< 5 g). Fish disease problems constitute the largest single cause of economic losses in aquaculture (Sudheesh et al., 2012). In 2018, over 100 tonnes of farmed tilapia died on lake Volta within a month. With tilapia being the second most cultured fish species outside its origin in the world, the SafeFish Project had come at a good time, titled ‘Development of bacteriophage cocktails as disease biocontrol agents for improved aquaculture productivity, food and nutrition safety in Ghana and Uganda’ could be a pragmatic intervention to help minimize some the mass fish kills among cultured tilapia.

This project is a three-year research and capacity building program funded by the European Commission (EU) through the African Union (AU) Commission.  It is implemented by a partnership of institutions in Uganda and Ghana, with Makerere University as the lead, CSIR-Food Research Institute as the lead partner in Ghana, and CSIR-Water Research Institute as well as the University of Cape Coast (Dept. of Fisheries and Aquatic Sciences), Noguchi Memorial Institute for Medical Research (Dept. of Electron Microscopy and Histopathology) of the University of Ghana and University of Leicester (Dept. of Infection, Immunity & Inflammation) as the supporting partners. These institutions would work by complementing each other due to the vast discipline or specialties, laboratory infrastructure as well as experience needed for implementation of the various activities. The action will offer a chance to create a consortium of phage researchers; sustainability and implementation of similar actions will be ensured through inclusion of graduate students in both countries.

The fisheries sector contributes to development goals, specifically the 14th Sustainable Development Goal (SDG) that emphasizes the need for countries’ support in restoration of fish stocks to improve safe and diversified healthy diets. Fish offers high quality proteins, higher amount of lysine and are nutritionally rich in polyunsaturated fatty acids compared to other meats (Nahid et al 2014). Declining capture fisheries have been experienced globally but effects have mostly impacted the developing countries due to the limited capacity to fill up the gap. High levels of malnutrition especially among children under 5 years of age have been reported in sub-Sahara African countries (Akombi et al, 2017). Hence, government efforts in promoting aquaculture is envisaged as a key player in contributing to sustainable fisheries resources management; improve food and nutrition security and the livelihood of smallholder fisher folk and the general community (MAAIF 2015). However, there are challenges to fish farming, such as diseases, which are mainly managed and/or controlled through application of antibiotics. Not only will fish disease contribute to food insecurity, the community will miss out on a cheap source of animal protein.

Use of antibiotics in animal production systems has been associated with drug residues in the animal products as well as development of drug resistant bacterial strains, which may spill into the human population. Alternatives to antibiotic use exist but are not widely applied in the African setting. Bacteriophages, tiny antimicrobial entities that ‘eat up bacteria’, are specific to the bacteria attacked; and as disease-control agents, they are cheaper and safer compared to conventional antimicrobial drugs. Hence this project, which aims at developing phage products for application on the fish farms, will play a role in fish health management and ensure safe fish, since even drug resistant bacterial pathogens are susceptible to the bacteriophages.

Application of bacteriophages targeting the economically important fish bacterial pathogens will reduce disease incidences, contributing to improved fish farm productivity and availability of fish both for human consumption as well as export. Improved productivity and use of cheaper disease biocontrol agents will enhance profitability of the fish farms, which will reduce on farmers falling out of aquaculture business. Additionally, use of phages is not associated with presence of undesirable residues compared to antibiotic applications, hence, in this respect, the fish products will be safer. In addition to SDG 14, the project will also contribute to SDG2; that is “End hunger, achieve food security and improved nutrition and promote sustainable agriculture”.


Therefore, the aim of the proposed project is to isolate and characterize lytic bacteriophages and evaluate their potential for bio control in farm Nile tilapia against various pathogenic and spoilage microbes that will be identified in samples of the fish from selected commercial fish farms in the country. The extent of pathogen contamination in various culture systems (ponds, cages, tanks, reservoirs etc.) of the fish in selected farms throughout the country will be assessed.  Bacteriophage will be isolated, characterized and an in vitro experimentation will be carried out. Additionally, field trials will be conducted using the characterized phage(s). It is expected that a phage product will be developed for integrated pathogenic fish disease prevention, management and control. This will ensure good survival of culture fish, high fish farm production as well as increase in the profit margin of small holder fish farmers in the country. Hence, the use of   antibiotics by tilapia farmers in the country to combat pathogenic diseases in farm fish will be reduced and farmed tilapia would be free of high levels of antibiotic residues.

  • Fish farming is promoted as a solution to declining capture fisheries.
  • The fisheries sector is important since it provides employment and high-quality animal protein and foreign exchange.
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Facts About Bacteriophages / Phages

  • Are naturally occurring tiny antimicrobial entities that infect and destroy/kill bacteria
  • Are ubiquitous entities found wherever bacteria exists
  • Are the largest biological entities known
  • Are host-specific i.e They are capable of living solely on or in one species of host. For instance, a phage that infects E.coli, will not infect the bacteria that causes tuberculosis. Therefore phages can be used to specifically target disease-causing bacteria without disruption of commensal bacteria (bacteria which normally exist in the human/plant/animal)
  • Are self-replicating (multiply by themselves)
  • Are self-limiting (limit their own growth by their actions)
  • Have diverse biological properties

Advantages of Phage Application Compared to Antibiotic Use

  1. Phages have high specificity to the target bacteria. Chemical antibiotics mostly target the essential metabolism of bacteria, such that they eliminate both the natural normal bacterial flora (commensal bacteria) and the unwanted pathogenic bacteria.
  2. Phages are auto-dosing while antibiotics require continuous sequential treatment to completely eliminate the target bacteria.
  3. The cost of production of potential bacteriophages or bacteriophage cocktails is relatively lower than the cost of formulating and producing novel antibiotics.
  4. Phages are self-limiting and would not persist when their hosts (target bacteria) are absent, whereas antibiotics may persist in the environment and/or in the fish and may cause long-term negative environmental impact and food safety.
  5. Phage use can minimize the development of antibiotic resistance by pathogenic (disease-causing) bacteria. (Source: Matsuzaki et al, 2005)
Some approval by regulatory authorities in America, Canada, and Europe for phage use in food

Phages used against Listeria monocytogenes

  • August 2006, LMP-102 phage was approved by the Food and Drug Administration (FDA) as a bacteriophage-based food safety product for application on ready-to-eat food.
  • October 2006, P100 phage was approved as a generally recognized as safe (GRA) product by FDA for use in brie, cheddar, Swiss, and other cheeses.
  • September 2010, Health Canada approved LISTEX P100 phage as a processing aid.
  • March 2012, the European Food Safety Authority (EFSA) confirmed that the use of LISTEX is safe.
  • Phage used against other bacteria.
  • January 2011, Dutch CBG approved SALMONELEX for field trials (received temporary use exemption) against Salmonella typhii. NB: A lot more research and approval is being conducted and granted for phage use in phagetherapy, biosanitation, biocontrol, biopreservation.

 Expected Results

  • Bacterial pathogens of economic importance for farmed tilapia in Ghana and Uganda identified.
  • Broad host-range bacteriophages selected
  • Effectiveness of different phage combinations will be established
  • Phage cocktail products for fish farm application formulated
  • Production practices influencing occurrence of fish spoilage and pathogenic bacteria documented
  • Awareness and buy-in for the fish disease biocontrol agents in the respective countries created
  • Capacity in research and development of phage technology in the East and West African region developed.

Key Stakeholders:

Tilapia fish farmers and the local government production officers, especially the fish extension officers, and/or regulators/policy makers.

Target Beneficiaries

Fish farmers including women or women groups; Inland fisheries sector in Ghana and Uganda; Fish traders/exporters, Fish processors, consumers, Line Ministries for Fisheries and Aquaculture.

Implementing Institutions 

 Makerere UniversityCOVAB College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Uganda
 naro logoNational Research Organisation (NARO) – National Fisheries Resources Research Institute (NAFIRRI), Uganda 
csir logo 120x120 CSIR-Food Research InstituteCSIR-Water Research Institute
 Univeristy of Cape Coast logoDepartment of Fisheries and Aquatic Sciences, University of Cape Coast, Ghana.
 Nogouchi logoNoguchi Memorial Institute for Medical Research, Department of Electron Microscopy and Histopathology; University of Ghana, Legon. 
 University of Leicester logoDepartment of Infection, Immunity & Inflammation, University of Leicester, UK. 


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