A novel computer simulation model for design and management of re-circulating aquaculture systems Ilan Halachmi a, * , Yitzchak Simon b , Rami Guetta c , Eric M. Hallerman d a Institute of Agricultural Engineering, Agricultural Research Organization, The Volcani Center, P.O. Box 6, Bet Dagan 50250, Israel b Aquaculture Department, Extension Service, Ministry of Agriculture, P.O. Box 28, Bet Dagan 50250, Israel c Faculty of Agricultural Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel d Department of Fisheries and Wildlife Sciences, 150 Cheatham Hall, Virginia Polytechnic Institute and State University, Blacksburg VA, 24061, USA Received 23 February 2004; accepted 28 September 2004 Abstract The aim of this study was to develop a simulation model for finding the optimal layout and management regime for a re-circulating aquaculture system (RAS). The work plan involved: (1) quantifying the effects of fish growth and management practices on production; (2) developing a mathematical simulation model for the RAS, taking into account all factors that directly influence system profitability; and (3) estimating the production costs and, hence, the profitability of an RAS. The resulting model is process-oriented, following the flow of fish through the RAS facility, and generates an animated graphic representation of the processes through which the fish passes as it progress through the system. The simulation assesses the performance in terms of yearly turnover, stocking density, tank utilization and biomass in process, and uses statistics to track the state of the RAS and record changes that affect efficiency. The economic impact of system design and operation was modeled to enable a user to anticipate how changes in design or operating practices, costs of inputs, or price of products affect system profitability. The proposed approach overcomes difficulties in characterizing RAS design and operation. The simulation approach allows all of the RAS’s www.elsevier.com/locate/aqua-online Aquacultural Engineering 32 (2005) 443–464 Abbreviations: BW, fish body weight; CAD, Computer-assisted design; CS, Computer simulation; DGD, Dynamic graphic display; DOE, Design of experiment; DXF, Drawing exchange format; I/O, Input/output; O–O, Object-oriented; PD, Probability distribution; RAS, Re-circulating aquaculture systems; SPL, simulation pro- gramming language; SQP, sequential quadratic programming; VIS, Visual interactive simulation. * Corresponding author. Tel.: +972 506 220 112; fax: +972 49 930 154. E-mail address: halachmi@volcani.agri.gov.il (I. Halachmi). 0144-8609/$ – see front matter # 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaeng.2004.09.010