As a basis for the evaluation of the functional roles of pelagic fishes and cephalopods in the fluxes of carbon and other elements in the ocean, I constructed an empirical model of metabolic rates of pelagic fishes and cephalopods as a function of body mass, habitat temperature. habitat depth and taxon. Such a model was established recently for major marine metazooplankton taxa while excluding cephalopods and fishes (Ikeda. 2OI4).For my purpose data from Laboratory-raised animals are of limited use. Hatchery fish have higher water content and lipid and lower ash than wild fish (Love, 1970). Sea bream (Chrysophrys major) raised in the laboratory on artificial diets exhibit higher carbon (C) and lower nitrogen (N) compositions than those from the wild (Annraku and Azeta. 1973). By measuring the lipid-class composition of laboratory- raised anchovy (Engraulis mordax) lavae under a variety of food regimes, Hakanson (I989) suggested the importance of low food concentrations to obtain larvae that have body composition similar to those of the wild larvae.