Based on recent advances in ecological network theory, we present an ad hoc conceptual framework and a methodological proposal for the evaluation of the ecological relevance of species within a community, oriented towards the Ecological Risk Assessment in Chilean aquatic systems. The procedure is theoretical and based on the quality of available information, i.e. it does not require experimental tests or field observation. Given the current and medium-term expected state of knowledge about the structure of local aquatic communities, the proposed method is focused towards its application to communities whose level of knowledge is low or medium. The proposal uses qualitative criteria and quantitative indices (seven topological indices and one index based on qualitative modeling) for the identification of ecologically relevant species that represent at least three trophic categories within the community