The objectives of this thesis are twofold: the first is to evaluate the financial viability of two water heating systems for fingerling production in Ontario. The second is to assess the existing biological fish growth models. The financial feasibility analysis uses a partial budgeting capital budget framework. A sensitivity analysis is used to illustrate how the economic outcome of the study will be affected by changing the assumptions used. Preliminary results indicate that neither water heating system yields a positive net present value. However, the annual benefits are greater than the annual costs in the solar heated system. The primary purpose of assessing the biological growth models is to highlight their differences from those models describing growth in other livestock and crops. The fish growth models follow a prediction equation approach rather than a production function approach. The evaluation also focused on the accuracy of prediction that the existing biological models provided and the results were disappointing. The biological growth models used initial fish weight and average water temperature as the two right hand side variables. There are several influential factors not included in the models which are accomodated through an ad hoc adjustment of a coefficient on the temperature variable. A model is introduced which describes several input variables and the appropriate functional forms that could be used to estimate fish growth using the production function approach.