The Hutchinsonian definition of niche is conceptually attractive, but lacks a quantitative, operational basis for analysis. Fry's autecological theories remedy the deficiency by permitting the use of metabolic units of measure that are observable, common, and important to all organisms and ecological functional groups. Contouring the niche hyperspace in units of metabolic scope for activity enables analyses at both the autecological and synecological levels of organization. A simple analysis of four coexisting percid species illustrates some applications of the method. Key words: community ecology, theory, Percidae, niche theory, prey size, light intensity, limiting factors