The aim was to formulate and evaluate, from the point of view and with private financing through government subsidy, a proposal for an additional investment business tilapia. The research was conducted in a region of the municipality of Amatepec, State of Mexico, from May to October 2014, in which information was seen coming from a farm producing tilapia species niloticus, to determine the effect of new investment government subsidy and fixed investment. Methodology development and evaluation of projects under certainty and uncertainty and sensitivity analysis of the situation with no less effect and without the project was used. The results made it possible to demonstrate the existence of commercial viability, technical and financial feasibility. With a discount rate of 12%, the profitability indicators without project were: 803.5% IRR and NPV 160.630 pesos, the project was 143.2% IRR and NPV 314.933 pesos; Furthermore, the effect of new investments (less free), generated an IRR of 75.8% and a NPV of 163.066 pesos. With the project, the tilapia business paid in 0.8 years and generated an additional profit of 314.933 pesos accumulated. The sensitivity analysis indicated that the business tilapia does not a selling price below 33 pesos per kilogram, or a lower level of sales to 2.4 t/year. We conclude that under the three scenarios, the tilapia business is profitable and its implementation is suggested. There was evidence that supports that tilapia business should leave its natural course and take advantage of new investment.