Greenwater Tank Culture of Tilapia with the Effluent Used as a Source of Water and Nutrients for Terrestrial Crops

Project Overview

Project Type: Research and Education
Funds awarded in 2000: $135,484.00
Projected End Date: 12/31/2005
Region: Southern
State: U.S. Virgin Islands
Principal Investigator:
Donald Bailey
Univ of the Virgin Islands

Annual Reports


  • Additional Plants: herbs
  • Animals: fish


  • Animal Production: manure management
  • Crop Production: multiple cropping, nutrient cycling, organic fertilizers
  • Education and Training: demonstration, on-farm/ranch research
  • Farm Business Management: budgets/cost and returns
  • Production Systems: integrated crop and livestock systems
  • Soil Management: soil analysis, nutrient mineralization, organic matter
  • Sustainable Communities: new business opportunities


    The grant funding provided for the construction of fish tanks for the production of tilapia in bacterial-based culture systems. Yields of 13 - 15 kg per cubic meter were obtained. This is 20 times greater than yields typically produced in pond culture. The increase in yield is attributed to the maintenance of an active culture of suspended nitrifying bacteria in the fish tank that removes ammonia waste through oxidation to nitrite-nitrogen and nitrate-nitrogen. Solids are removed by settling. Electrical use is higher in this system than in pond culture but not prohibitive. Over 4,000 market size tilapia of 700 g each were obtained in the final trial.

    One farmer constructed a fish tank near his vegetable garden site and will be able to use water from the fish tank for irrigation of the crops produced. Land ownership, zoning and environmental permitting prevented the construction of a second fish tank at another farm site.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.