One real constraint to expanding production from aquaculture is the lack of knowledge or information on the economic relationships between inputs and output, in other words between what goes into a pond and what comes out. In the case of Philippine milk-fish farming, the inputs include everything from seed (fry or fingerlings) to farm labor, feed, fertilizers, pond maintenance and repairs, rental and pesticides. Some other variables that can affect production relate to the experience of the farmer and the size, age and tenure of his ponds, as well as their geographic location. The Philippine milkfish industry involves at least 150,000 people servicing farms totalling close to 180,000 ha which produce some 115,000 tonnes annually. Recognizing the importance of the contribution that knowledge of these relationships can make to this industry, the Fishery Industry Development Council (FIDC), the Bureau of Agricultural Economics (BAEcon) and the International Center for Living Aquatic Resources Management (ICLARM) jointly undertook in 1979/80 a study of milkfish input-output relationships in a broad sample of 324 farms over the whole archipelago.