The use of bioenergetics models in fisheries ecology and management has increased rapidly in recent years, but application-specific information on energy content of fish and their prey has lagged behind. We believe this is because the process of directly measuring energy density is very time consuming. In this paper we present and evaluate a series of general empirical models that predict energy density (J/g wet weight) from fish percent dry weight. Data were gathered from the literature, obtained from cooperating investigators, and measured directly. Least-squares models were derived for all species combined and for orders, families, and species. All models were linear; however, logarithmic transformation was necessary to normalize residuals in the combined model. All models with more than four data points were highly significant (P< 0.002) and had coefficients of determination of 0.76 or greater. The model for all species combined (N= 587,r2= 0.95) was J/g wet weight = 45.29 DW1.507; DW is the percent dry weight of the fish. At all taxonomic levels, energy density models showed a strong positive relationship between energy density and percent dry weight. This relationship, if corroborated, should allow the estimation of seasonal and ontogenetic changes in energy density based solely on percent dry weight data.