An ecological study of the geographical distribution of aquatic Adephaga and Polyphaga (Coleoptera) in the mountains of northern Tunisia was carried out with an analysis of the effect of altitude on the distribution of 123 species collected from 64 sampling sites. Species richness was analyzed at different altitudinal levels and the indicator species were determined by establishing their altitude profile in terms of reciprocal species-factor information. Species richness decreases with increasing altitude. Thirty representative species are placed into three groups: species present along the entire altitudinal gradient; species present at high altitude; and species occurring at low altitude.