Fish Farm Design

Aquaculture is a rapidly growing food production system with the annual global increase being between 3-4% off a base of 131 million tons of production in 2022 (FAO 2025).  The size of the industry indicates that it is mature, and there are many sectors and technologies that have been proven to work well.  However, due to the rate at which innovation is occurring in the 21st century, new technologies are continuously being tested and refined within the industry to reduce costs whilst improving outputs and/or margins.
 
When planning an aquaculture investment there are several different infrastructure options to choose from, including RAS (recirculating aquaculture systems), earth ponds, cages, through flow, biofloc and aquaponics.  It can be bewildering for a newcomer to assess these, along with the many species options and market opportunities, to determine the optimal selection for a specific situation.  The climate in which the farm is to be established is the first consideration in selecting infrastructure, but this cannot be done without also considering the market and site, as both can have a major impact on the infrastructure choice.
 
Fish farming infrastructure types can be viewed as being on a continuum from through flow systems, where water from a river flows continuously through the tanks containing the fish, to RAS which have a very low daily exchange of new water.  In the case of through flow systems an enormous amount of water is required to replenish the oxygen used by the fish and wash away their wastes.  In this case the chemical, temperature and health components of the water cannot be effectively managed, but the operational costs of such systems, when used for the right species in a suitable location, can be low.  By contrast, a RAS relies on continuous electricity and powerful filters to maintain optimal water quality for the fish, but this creates an environment in which wastes, water quality and temperature can all be maintained close to the optimal levels for the species being farmed.
 
Once you have determined which infrastructure type to use in your situation, the next step is to design it.  The market you plan to supply will play a role here, but the major decision relates to the level of technology that you are comfortable deploying, or which is appropriate to deploy.  High-tech systems are available from the EU and USA that can produce impressive tonnages of fish from a small footprint, but these systems are built around specialised equipment that requires skilled technicians to operate and yet more specialists to provide servicing.  These skills are generally unavailable in Africa, adding significant risk to the business as these systems are mechanical and can fail.  I have witnessed several RASs where drum filters were used and the failure of these items caused major catastrophe for the farmer. For example, the collapse of bearings in a drum filter can take several days to repair, during which time the production system either fails or operates through an expensive by-pass system.  In Africa it is needless to utilise such expensive, high-tech equipment when there are options available that are both simpler and less expensive, along with them being able to be serviced on site.
 
Another common error made by inexperienced designers is to utilise piping that is too narrow.  Modern RAS utilise pumps that achieve high flow rates but at a low head to circulate water.  Utilising pipes that are too narrow increases frictional resistance that the pump needs to overcome, resulting in reduced flow rate and compromised water quality.
 
The various equipment components that Aquaculture Solution’s uses are supplied by manufacturers that we know and trust, having utilised their products for decades.  From the many options that we trialled on our own farm we remained with those that were reliable and cost effective.
 
My preference in designing fish farms is to adhere to the technical and biological principles, with an appropriate safety margin, but within these parameters to utilise simple, effective, dependable equipment and technologies.  In our designs, component and equipment selection is based on straightforward technologies that are less likely to fail, and are divisible into units that can be run in parallel and are relatively inexpensive, thereby providing insurance against failure and loss.  These systems are easily operated by staff with reduced skill levels and can be serviced on site.  It is, however, still critical that the scaling of the system be done correctly to ensure that the desired tonnage of fish can be produced from the invested infrastructure on a continuous basis.
 
When planning the layout of a fish farm be sure to consider expansion at a future stage to ensure there is adequate land and water available for the additional infrastructure.  All the designs should be executed in such a way that existing units can be expanded or duplicated. Since our designs are based on optimisation around key equipment components, we prefer duplication.  Restricting staff access to their areas of work also enhances biosecurity across the farm and separate systems allow for this, again favouring duplication rather than expansion.
 
Aquaculture systems fulfil many of the Millenium Development Goals of the United Nations as a food production technology that can be conducted in a small area, using minimal water, upskilling and employing people, whilst producing high quality food.  As the worldwide fish farming industry continues to grow it is important that investors rely on experienced professionals to design and install their facilities for them to avoid loss, either through failure or as a result of system under-performance.