We might conclude that to have a functional stomach at the time of the first exogenous feeding is not a prerequisite of FAA diet utilization for body growth. Fyhn (1989) coined the hypothesis that ‘artificial first feed of fish larva (will benefit from) a pool of free amino acids matching that consumed by the fish embryo during endogenous feeding’. Rønnestad, Thorsen and Finn (1999) followed this suggestion and argued that ‘amino acids, preferably in their free form, should probably comprise a major component of the diets of early larvae’. Further, based on a comparison of absorption of free and protein-bond amino acids intubated to juvenile teleost fish, the authors argued that ‘free amino acids seem to be superior to protein as a dietary source of amino acids …’. However, Rønnestad, Conceição, Aragão and Dinis (2000) and Rojas-García and Rønnestad (2003) used methylated-bovine serum albumin, a protein used as a marker for radioimmunoassays, with dimethyl-lysine ester specifically resistant to trypsin enzymatic digestion. The authors overlooked the fact that a methylated protein transforms into a non-digestible molecule, and makes the comparison of protein and FAA absorption useless.