Introduction
Global production of cultured carnivorous fish in- creased from approximately 1.6 x 106 metric tonnes (mt) in 1991 to 2.8 x 106 mt in 1998, an increase of 70% (FAO2000a). These fish are reared on trash fish or high protein (400-450 g kg-1) compounded dry diets in which fish meal is the predominant source of protein (New 1996; Hardy & Green
1999; Tacon 1997). Supplies of trash fish and fish meal are becoming less plentiful as world demand from aquaculture continues to increase while wild fishery catch remains essentially static (FAO
2000b). The global aquafeed industry is estimated to use annually in excess of 2 x 106 mt of fish meal, accounting for 25-30% of the world s average annual fish meal production (Pike 1997; Tacon
1997). For aquaculture to become a net contributor to human food supplies, the present use of fish meal in aquaculture diets must be substantially reduced. This will be possible only if more renewable terres- trial protein meals can be shown to be cost-effective alternatives to fish meal in aquaculture diets.