How to farm fish on land

About RAS

Recirculating aquaculture systems (RAS) are a land-based production technology for aquatic organisms and high-value finfish. They utilise simple water treatment technologies (mechanical and biological filtrations) to minimise water use and maintain a tightly controlled environment. These can range from very open systems that use only basic treatment technologies to reuse some of their water resource, to fully closed systems which reuse 100% of the water and only add new water to account for splashing and evaporation. RAS vary in their design and functionality depending on the species being produced, the local conditions and the cost/access to a local water resource.

Advantages of using RAS

  • Reduced water requirements 
  • Water is treated and recirculated, significantly reducing water requirements. 
  • Production Control
  • Water can be heated/cooled, high oxygen can be maintained, pH adjusted, pathogens treated, and waste products removed to maximise health, growth rates, and the welfare of the stock. 
  • Increase in long-term production
  • Stock are unaffected by seasonality, periodic disease events and adverse weather, allowing continuous and reliable production.  
  • Reduced environmental footprint
  • Waste streams are treated and recycled to ensure they have the least impact on the environment as possible. Being land-based, there is also no risk of fish escaping and interbreeding with wild populations. 
  • Flexible design
  • The system can easily be customised for different species, locations and consumer preferences. 
NIWA contacts D7: 
Research subject: Aquaculture