On average, OECD inhabitants of cities live more sustainably than those who live in suburbs and rural areas. This is not necessarily so in less developed countries where a large portion of the rural population relies mostly on manual labor and subsistence farming. Since standards of living are rising in most of the world, we must look to the role of urbanization in minimizing the trade-offs between economic development and protection of natural resources. While Curitiba often gets much attention for its sustainable practices, Singapore is increasingly in the news for its innovative contributions. This article describes an apartment development for senior citizens that incorporates food crops that supplements their diets and keeps them more active. This system incorporates fish culture to utilize fish wastes to fertilize the crops. This short video of an indoor aquaponics farm in Canada shows how it is already being done on a commercial basis. In this other post I located an article on then current economic viability of urban farms in the U.S.