This paper briefly describes marine cage aquaculture in Khanh Hoa Province, Vietnam. Tropical marine cage culture is attracting increased attention, partly related to the search for alternatives to shrimp culture. Relatively small-scale and limited production has been underway for many years in Vietnam, based mainly on the fattening of wild seed of various grouper species, and lobster. Production takes place mainly in simple hanging net cages, stocked with wild caught seed, and fed with “trash” fish. The aim of this project was to determine whether current use of seed and trash fish is sustainable, whether the use of trash fish affects the price or availability of low cost nutritious fish for human consumption, which (if any) of the various options for marine cage culture is most suited to poverty alleviation and what the economic constraints may be.