A means for determining the nutritional requirements of fish is provided. The nutritional requirements of fish is determined by comparing the amino acid sequences of proteins predicted from genome information of fish with the amino acid sequences of known proteins thereby to estimate the functions of the respective proteins of the fish, identifying a metabolic pathway present in the fish on the basis of the estimated functions of the respective proteins, and determining the nutritional requirements of the fish on the basis of a difference between the identified metabolic pathway present in the fish and a metabolic pathway present in a reference organism.
