Recirculating Aquaculture Systems

The purpose of aquaculture is to produce fish to sell at a price that exceeds the costs of producing the fish, enabling the farmer to make a profit. Different types of infrastructure can be used to achieve this purpose including earth ponds, raceways, cages and recirculating systems (RAS), so how do we decide which is best suited to a particular situation?

The first consideration relates to the climate in which the fish is to be farmed compared to the optimal temperature required by the fish for fast growth (which is imperative in commercial aquaculture). If there is a close match then the fish can be farmed under ambient conditions either in cages or earth ponds. However, if there exists a significant gap between the climate and optimal growth temperature for several months of the year, then neither option is suitable and the fish need to be farmed under temperature-controlled conditions within a RAS.

Having stocked the fish into insulted infrastructure which is heated and/or cooled to maintain close to optimal conditions year-round, we need to filter the water to remove the toxic metabolic wastes produced by the fish. This entails the addition of mechanical and biological filters, as well as oxygen replacement to ensure that growth is not compromised. Each of these components has a vital role to play but its inclusion adds to the cost of producing the fish, thus where the climate is suitable one would prefer to use earth ponds or cages which do not include these expensive components. Yes?

Not necessarily. Even in the perfect climate there are advantages associated with farming under the controlled conditions offered by a RAS that are worth considering. Within a RAS the reliance on new water is minimised, a relatively small amount of space is required, the infrastructure can be located close to the market or feed manufacturer, and many other advantages favour RAS systems. Certain markets require a high level of traceability whereby each individual fish can be tracked back to its parents and contamination risks need to be minimised, and these are most easily achieved in a RAS. A hugely important advantage offered by RAS is the exclusion of diseases. If the potential vectors are managed and a disciplined biosecurity protocol implemented and followed, diseases can be excluded. It is my expectation that as aquaculture scales up across Africa we will experience the parallel development of drug resistant and novel diseases that will be devastating to outdoor farms. This need not affect farmers utilising RAS technology, giving us a strategic advantage.

The solution is to plan the aquaculture facility appropriately and ensure that all vectors are managed to exclude disease elements. Whilst managing the health side of the business you will also benefit from the many other advantages including optimal growth rates, enabling you to farm for profit.

Aquaculture Courses
We have scheduled the following Aquaculture Courses planned for 2018:
17 to 21 September Practical Aquaculture Course, Aquaculture Academy, Grahamstown – This is an excellent opportunity to obtain both the theory of fish farming as well as practical experience in spawning tilapia and catfish, feeding correctly, managing water quality, sorting fish, aquaponics plant care and many other related skills.

24 to 26 September Aquaponics Course, Pretoria

22 to 25 October Aquaculture & Aquaponics Course, Windhoek, Namibia

19 to 22 November Aquaculture & Aquaponics Course, Lusaka, Zambia

To obtain further information email us on

Catfish, Trout & Tilapia Fingerlings for Sale

We have catfish, trout and tilapia for sale.  Send us an email if you are interested in obtaining stock.

This year we have a limited number of female O. mossambicus for sale as breeders.

Aquaculture Products for Sale

We offer a wide range of products to the Aquaculture Industry.  These products can be viewed and purchased from our secure online store at Aquaculture Store.

If you need anything that is not listed, drop me an email and I will attempt to source it for you.

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