This paper describes a general bioeconomic model, FISHSIM, which uses traditional equations and submodel to represent the biological parameters of a fish stock, and simple financial equations to represent profitability of thefishery. FISHSIM allows the user to enter the biological and economic parameters of a fishery, or to see the program run with built-in parameters. The model simulates a fishery over a 50-year period, during which the user may stop the run (for policy intervention), and alter fishing effort and age at first capture. The output of the model includes graphs or annual recruitment, fishing effort and catch weight. The full executable version of FISHSIM is available from the author's institution.