The definition,nomenclature,methodology,main aspects and research directions of the ecomorphology(or ecological morphology) of fish were reviewed on the basis of collected literatures in this paper.Ecomorphology is a comparative discipline;the central goal is the study of the interactions between the morphology of organisms and their ecology both in the present and over evolutionary time.These interactions can be studied at multiple levels: among individuals within a species,among species and higher taxa,among guilds and communities.From an ecological perspective ecomorphological studies have three aims:(1) measurements of the correlation between general morphological variation and ecological variation;(2) making ecological inferences from morphological pattern;(3) determination of the underlying morphological mechanism that influences resource use by an organism and the degree to which ecomorphological relationships are influenced by other factors.The main aspects of ecomorphological research include application of a more functional approach to the choice of characters,integration of morphological,behavioral,and physiological information to address adaptation,and the expansion of spatial and temporal(ontogenetic and evolutionary) scales of ecomorphological questions.In the future,research directions for ecomorphology include additions to the knowledge base,further integration of information from other disciplines,examination of the relative contribution of genetic versus environmental factors in producing and maintaining ecological and morphological diversity,and insights from ecomorphological studies used to reveal the composition of ecological communities and predict the impacts on existing communities by biotic or abiotic disturbance,including species introductions or other anthropogenic manipulations.