This volume reports the findings of the ICLARM-BMZIGTZ Africa Aquaculture Project (1 986-1 994). The project studied smallholder farming systems and developed integrated aquaculture technologies in collaboration with the Malawian Department of Fisheries, the University of Malawi and the Ministry of Research and Environmental Affairs. The project began with a comprehensive survey of the ecological and socioeconomic context in which Malawian smallholding farmers must earn their living. The majority of the enterprises on these farms are resource-limited and use, for the most part, traditional farming methods which are increasingly unproductive and inadequate in light of expanding population pres- sure. One important consequence of the failure of traditional agriculture to meet human needs is environmental degradation associated with bringing marginal land into agriculture, and the overexploitation of fragile ecosystems. To ameliorate this situation, technologies which could take advantage of existing on- farm resources to improve productivity and environmental sustainability were developed in on-station trials at the Malawi National Aquaculture Center. Suitable species from within the Malawian indigenous species flock were selected and their culture characteristics were described. Crop residues and weeds which could serve as fishpond inputs were identified. Methods for the use of fertile pond water and mud for vegetable production were devised. Integrated crop-fish and animal-fish systems which improved the profitability and productivity of the whole farm were designed. These technologies were demonstrated to extension agents and packaged into extension booklets for transfer to farmers. Adoption of these technologies by smallholders using the existing extension approach and infrastructure was, however, less than was hoped for. To resolve this problem, farmers were approached directly for feedback. From their response, it became clear that more than just potential fish production was important in determining whether or not a particular farmer would adopt aquaculture. Among other things, the perceived ease with which fish culture could be inserted into the existing farming system was crucial. For example, adoption rates of rice-fish farming technology were much higher if the farmer had experience with either rice or fish. The perceived simplicity (or potential risk) of the technology was also critical. If farmers were presented with a lot of details and options for maximizing fish production (e.g., oxygen cycling, role of pH, calculation of feeding rates and sampling protocols, etc.) during the initial introduction of fish farming, most farmers would not participate. Those who were presented only with the idea that a hole, filled with water and fed with wastes from other farm activities could produce some fish were much more likely to adopt the technology. That farmers were more concerned about these issues than about the theoretical profitability of adopting aquaculture was a revelation to the researchers. It was previously assumed that a demonstrably better system of food production would be immediately adopted and that the constraints were largely related to the ability of the extension agents to explain, and farmers to grasp, complex ideas. In actual fact, the decisionmaking of farmers is far more complicated than that. The project found that constraints to adoption were best dealt with by letting the farmers decide what technology they would like to use, regardless of its productivity relative to other technologies. In other words, the socioeconomic constraints to adoption of aquaculture (e.g., lack of investment capital and social leveling mechanisms) are exacerbated when extension agents and scientists attempt to impose technology on farmers. To determine how farming systems evolved as a result of the adoption of fish farming, methods of participatory rural appraisal were adapted for use by researchers. This was combined with monitoring tools developed for farming systems research. This permitted the measurement of the impact of the integrated farming systems which were being promoted by the project and related extension programs. Profitability of farms participating in pilot studies was doubled, on average, and efficiency of production of vegetable gardens was improved. The simple systems which were adopted became more sophisticated and pro- ductive as the farmers became more familiar with fish farming. To improve the technologies which were being presented to farmers and make these more immediately appropriate to their needs, a new set of research protocols was estab- lished. Rather than use an idealized optimal management strategy as a control of treat- ments, the actual types of materials available on smallholdings were applied in the amounts used by farmers. This dramatically reduced the productivity of the pond, but the amount of fish produced was much closer to what the farmers could realistically expect. Conducting research in this way forced scientists to interact with farmers during weekly visits and learn more about their constraints and perceptions. Scientists and farmers must communicate with each other if truly useful research is to be conducted and the results adopted by farmers. 