Of the flesh foods eaten by humans, fish have the highest feed
conversion ration. Every 1 Ib of feed yields about 0.67 Ib of fish. Fish also require much less space than other animals.For example catfish, space requirements are about 2500 Ib per acre (2750 kg per ha); silo systems can reportedly produce about 1 million Ib of fish per acre (1.1 million kg per ha).
This fact suggests that fish for human use will eventually be produced largely by fish farming. It may be that the situation is beginning to change.
Methods of culturing oysters, clams, mussels, abalone, shrimp, crawfish, crabs, northern lobsters, salmon, catfish, carp, buffalofish, milkfish, tilapia, shad, striped bass, trout, mullet, and plaice are being investigated in various countries.
In some countries, several freshwater species (catfish, carp, trout, and tilapia) have been raised as a commercial enterprise for some years and milkfish have been raised for many years in the Philippines.
Oysters are now grown commercially in some areas, and the raising of shrimp in Japan is already commercialized.
Fish and shellfish
