Aquaculture: Put food on the table and earn a promising extra income

Aquaculture is enjoying unprecedented growth worldwide. For local farmers, it offers an opportunity to diversify profitably.

Aquaculture (fish farming) is not a quick fix to get you out of trouble but is rather a diversification that can help your cash flow if your main farming enterprise is taking strain.

Charles Marais, an aquaculture expert with 25 years’ experience, is currently the project manager of a new Mozambique tilapia farming enterprise between De Wildt and Brits in the North West province of South Africa. He believes that the fresh-water aquaculture industry is on the threshold of a major revolution in South Africa.

Charles Marais

“Aquaculture has the potential to achieve food security in the country on smaller pieces of land, while at the same time providing established farmers with a useful financial tool.”

This is consistent with a finding by the United Nations Food and Agriculture Organization (FAO). In its report entitled “The State of World Fisheries and Aquaculture 2016,” the FAO said that the production of fish has major potential to make a significant contribution to food security and to provide adequate nutrition for a world population expected to reach 9.7 billion by 2050.

The report points out that fish is one of the food products that trades the best worldwide. More than half of the fish being traded comes from developing countries.

The global supply of fish for human consumption has grown faster than the population growth over the past five decades. The growth rate in the supply of fish was 3.2% per year from 1961 to 2013, which is double the population growth rate of the world.

Together with this, world consumption of fish increased from an average of 9.9kg per capita per year in the 1960s to 14.4kg in the 1990s and to 19.7kg in 2013. In developing countries, the annual consumption of fish increased from 5.2kg per capita in 1961 to 18.8kg in 2013, while the consumption in developed countries was 26.8kg per capita.

The report says that in developing countries, where the consumption of fish is normally determined by what is available locally, consumption should be driven by supply rather than demand. This creates the ideal environment for local farmers to create a market for the products themselves.

Before people can be fed and food security can be established, there needs to be farmers who are making aquaculture systems work.

Charles has developed a system which is significantly cheaper than existing aquaculture systems and is also making it easier to manage aquaculture enterprises.

The layout of the aquaculture enterprise. Fish can be successfully produced in a space of 50m x 10m. A tunnel will ensure that the water temperature is kept constant.


“Building a hi-tech system can easily cost a farmer a few million Rand. In contrast, the input costs of our system are about R400 000 ($30 140) with running costs of R30 000 ($2 260) per month. A system that is too complex usually gives more problems and increases costs,” says Charles.

The system, which was installed on Frank le Roux’s farm, is a simplified breeding and growth system that produces fish weekly – these are destined for the informal market.

“Unfortunately, aquaculture is still seen as a quick fix when drought make things difficult for farmers. It doesn’t work like that. Farmers should diversify precisely when it’s going well so that the different farming divisions can support each other in difficult times, such as during a drought.

The two breeding dams in which the breeding pairs are kept. A Mozambique tilapia female weighing about 1kg lays around 1500 eggs every 20 days in summer.

“Aquaculture is not a quick fix. It takes six months before the first fish are market-ready. At a cost of R30 000 ($2 260) per month this means you have expenditure of R180 000 ($13 560) before an income is provided, but a potential income of about R80 000 ($6 030) per month, with a net profit of R55 000 ($4 144) per month is possible with this system,” says Charles.

Therefore, he says, farmers must build a system that works. “If you build a system that doesn’t work, you’re wasting your money.”

For the system to work, you need a dam that holds about 300 000 litres, lined with plastic, and covering an area of about 51mx 10m. The dam is equipped with nets to keep the bigger fish away from the smaller ones; this prevents the big ones from eating the young ones. Normally, Mozambique tilapias achieve a marketable weight of 500g within eight months. By heating the water, you also get growth throughout winter.

The farm breeds its own fish, but prospective farmers are encouraged to rather purchase fingerlings because it is a complicated division of the enterprise.

The biggest issue for an aquaculture enterprise is to maintain a constant temperature. The ideal water temperature of 25°C is obtained when the fish system is housed in a tunnel and the water is circulated through black plastic pipes. “By putting the dam in a tunnel, you already gain 10°C, while the pipes add another 5°C. This means that we can maintain a constant temperature even in winter,” says Charles.

The system requires 40 000 litres of borehole water a week. The used water is recycled for use in vegetable production. Charles’s system uses a standard 1.1 kW pool pump and filter to circulate the water, while an air pump specially designed to aerate ponds provides the necessary oxygen to the system. These pumps run constantly and represent the total electricity consumption of the fishery.

Charles says the single biggest expense is the cost of feed. Therefore, he recommends that farmers, where possible, look at cheap feed to reduce expenses. “Once your feed costs are reduced, you can better control your costs and then you can lower the price of your product.”

Nets, made of special material, are used to keep bigger fish away from the smaller ones. The nets are dropped into the dam and can be pulled up to clean the ponds or to monitor the growth of the fish.


He says the informal market is the aquaculture farmer’s best friend. He recommends that farmers look at outlets within their own areas to find suitable markets for their fish products.

“In light of the large number of potential consumers currently in South Africa, this is the best route to follow. Market to vendors who provide fresh products to their customers, allowing you to bring your product directly to the consumer. The only major watchword here is price – make sure the price you ask for your fish is not too high,” he says.

Frank Le Roux

Charles Marais’ tips for sustainable aquaculture

  • Save money on fish feed. This is the major running cost and by using cheaper foods, you can improve the profitability of the enterprise.
  • Stick to the basic requirements of aquaculture. These include heating the water, replacing the water and proper nutrition.
  • Replace 40 000 litres of water per week in the system.


  • Inquiries –  Frank le Roux cell: +27 83 645 5001; Charles Marais cell: +27 82 396 7798.

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