Recirculating aquaculture systems

Recirculating aquaculture systems are indoor, tank-based systems in which fish are grown at high density under controlled environmental conditions. Generally, farmers adopt a more intensive approach (higher densities and more rigorous management) than other aquaculture production systems.

Recirculating aquaculture systems can be used where suitable land or water is limited, or where environmental conditions are not ideal for the species being cultured. This type of aquaculture production system can be used in marine environments; however, it is more commonly used in freshwater environments.

There is a large cost involved in setting up and running a recirculation system and you will need to consider a number of factors in designing the system that will fit your needs.

Characteristics of recirculating aquaculture systems

Water quality

The water in the system is recirculated through tanks and a series of water treatments to remove waste products. Unless the water is treated, fish will stress, resulting in retarded growth, increased pre-disposition to disease and finally death. You should have a good general knowledge of the principles of water chemistry and a good knowledge of the biology of the species being cultivated.


Production tanks vary in size and shape. Smooth, round tanks with sloping bottoms are useful as solids can be concentrated and subsequently removed from a centre drain. This design facilitates thorough cleaning and ensures aeration is evenly distributed.


In simple recirculation systems, water may be treated by two processes: mechanical filtration (to remove solids such as faecal matter, uneaten feeds, etc.) and biological filtration to remove dissolved toxic wastes.

Other system components

Depending on your location and the species you are planning on farming, you should consider including other components such as disinfection devices, foam fractionators (or protein skimmers), dedicated aeration units and temperature control.

Support equipment and facilities

You should also make sure you have access to water quality testing equipment, a purpose-built facility to accommodate bulk feeds and hygiene measures to limit the spread of disease.

Suitable species for recirculating systems

The design of your recirculating aquaculture system will depend on the specific requirements of the species you want to culture.

When designing a recirculating system, it is important you understand the impact of different factors on a species. These factors include water quality requirements, stocking density and size of stock, feed types and disease.

Things to consider

The costs of establishing and operating a viable recirculating aquaculture facility are usually much higher than most people anticipate.

We have developed Aquaculture industry tools for pond and tank-based systems growing barramundi, silver and jade perch, marine prawns, redclaw and rock oysters. These economic models can help you to assess the merits of developing a farming venture.