The competitive position of small-scale fish production, compared with other activities, was assessed in terms of its net returns above costs, protein, and welfare effects on Rwandan households. The purpose was to determine whether small-scale fish culture made the best use of land. Fish culture was compared with sweet potato, irish potato, cassava, taro, sorghum, maize, red beans, soybeans, and cabbage production. Whole farm enterprise budgeting and quantitative systems for business (QSB) techniques were applied to analyse pond records and data collected through personal interviews with 267 farmers. Results indicated that small-scale aquaculture was the most expensive way of producing protein after cassava. Soybean was the cheapest source of protein for rural farm households. With trade, small-scale aquaculture was competitive with the other enterprises for the use of scarce resources. Tilapia production was the most promising enterprise for augmenting, within the farming system, the rural farm household's welfare in a subsistence economy like Rwanda.