Both graywater and nutrient rich liquids or stabilized solids from primary treatment processes can be used as feedstock in fish and/or water plant farming.

Treatment Level:  Secondary 
Relative Cost:
  medium – high
Amount of Maintenance Interaction:  medium – high
Beneficial Byproduct:  lots (fish and/or plants)


  • Low energy waste treatment that aides in fish production.
  • Food security and nutrition.


  • Large space needed for fishponds.
  • Extreme care must be taken to avoid potential bacteria in pond water, on plants and on the fish.
  • Need access to experts to develop a  hazard and risk management plan.

Operation & Maintenance

  • After waste/graywater has been treated and/or stored for 4-10 weeks, add it to the aquaculture pond.
  • Visually inspect for undesirable vegetation, insect larvae growth, and snails.
  • Pond water quality is essential to avoid contamination and pathogen transmission.  It should be monitored to set waste application and timing.

Additional Notes:

  • Aquaculture fish and plants should not be eaten raw.
  • Kitchen processes must be adjusted, such as using separate gutting and cutting knives, to avoid cross-contamination of fish flesh.
  • Good practice is to keep fish in clean water ponds (or eliminate waste feed to ponds) for several weeks at the end of their growing cycle.

Salmon Aquaculture Project (