PES of a project to determine the feasibility of developing a large-scale managed fish production program as a way of increasing the nutritional status of Panama's rural poor. PES covers the period 6/81-4/85 and is based on an attached economic analysis (XD-AAT-440-A). The project failed to verify the feasibility of large-scale managed fish production. To have expected villagers to learn aquaculture - for them, a new technology - and to integrate it with high intensity livestock production in such a way as to realize a high rate of return within 2 years was unrealistic. Findings of the economic analysis and of other studies indicate marginal economic benefits and complex administrative and social constraints to achieving technical self-sufficiency. The attached economic analysis has some drawbacks. Although its methodology for measuring the returns to fish culture - by analyzing fish with four types of livestock (cattle, swine, chicken, and ducks) and fish alone - is basically correct, it excludes TA costs and implies a goal which requires a higher standard of living than the severely poor targeted by the project. The analysis is also cumbersome and difficult to review in detail. Its avowal of negative returns to livestock production is likely incorrect, since livestock is what farmers are currently engaged in. However, economic analysis, at best a complex task, was virtually impossible to achieve under the project's conditions. To determine meaningful costs and returns from the start-up phase of a complex, highly integrated rural development/food production project in a resource-poor area should not have been attempted in an evaluation context. Also, a 1983 drought, the worst in 75 years, not only lowered output in all livestock operations, but weakened the validity of the data base. In the context of lessons learned, the analysis does indicate that the integration of fish farming as a supplement to other livestock activities is a viable means of increasing net income, or of lowering protein production costs. Fish farming alone is only viable if the value of fish is relatively high and if TA is excluded as a cost. No further USAID/P assistance to aquaculture is planned at this time, although the Direccion Nacional de Acuicultura (DINAAC) will continue to monitor control ponds in order to maintain the data base.