AN EVALUATION OF A CONFINEMENT CATFISH PRODUCTION FACILITY INCORPORATING RECIRCULATING CULTURE SYSTEMS WITH FISH-BARN: A SIMULATION FOR AQUACULTURE ANALYSIS (IETALURUS, MODELING)

Algorithms were developed from the literature and organized into a model for evaluating a catfish grow-out facility incorporating high density, recirculating culture systems. From insulation values, equipment usage, air and water temperatures, relative humidity levels, and climatic data an energy budget and seasonal heating, ventilation, and air conditioning schedule were generated. Production data and prediction of ammonia and nitrite concentrations were based on feeding rates, feed conversion efficiencies, water temperature and pH, nitrification efficiencies, recirculation rates, and sludge removal schedules. Dissolved oxygen concentrations were generated from aeration efficiencies, water temperature, and fish consumption rates. The model allowed the assessment of building and production system designs and water use on energy requirements and the ultimate impact on water quality and production. Ammonia, nitrite, low dissolved oxygen and large stocking rates have been shown to have negative impacts on catfish production. The model allowed the assessment of production without these impacts, with each impact individually, or in concert, and how they can be influenced by managerial practices. Although the water quality constituents tested could each impose major reductions in production, all were found to be manageable. Ammonia was found to impose little or no impact on production if reasonable management practices were employed. Nitrite was determined to be the most influential constituent except under extreme operating conditions. Commercial acceptance of recirculating system technology has been restricted due to the perception of high energy costs, particularly for heating. Under accepted water use practices, heating requirements of the water could represent the greatest single energy requirement. However, use of freshwater additions could be restricted to sludge management only with little impact on water quality, thus reducing heating requirements substantially. Aeration and filtration represented about 80% of the total energy budget of a hypothetical facility