Fish farming is in fact expanding in the state, although at a much more modest rate than is occurring at the global level. That it will outpace cattle ranching as a food source by the end of the decade is not even a possibility. Yet the World Watch Institutes's report of the benefits of aquaculture raises some interesting issues relevant to Arizona. The report states aquaculture allows a more efficient use of natural resources than does cattle raising as measured by the efficiency with which fish convert grain into protein. Cattle require about 7 kilograms of grain to add one kilogram of live weight.
Fish are able to add a kilogram of live weight with less than two kilograms of grain.
Also, grain saved is water saved, since it can take 1,000 tons of irrigation water to produce one ton of grain. Kevin Fitzsimmons, researcher at the University of Arizona's Environmental Research Laboratory, describes further ways that fish farming in Arizona encourages an efficient use of the state's limited water resources. He says that aquaculture and agriculture can be pursued together as complementary activities, with both operations sharing a single source of water. Water therefore is more intensely used. Agricultural water is generally confined to ditches and canals, and water thus controlled and managed is suitable for fish farming.