Densities of Corixidae (Hemiptera), larval Odonata, and large larval Trichoptera were estimated in the littoral zone of small lakes in an acid-stressed area near Sudbury, Ontario . Fish were present in some lakes and absent in others, and fishless lakes occurred across a wide range of pH . Corixidae were significantly more abundant in lakes without fish than in lakes with fish, and their numbers were not related to the pH of fishless lakes . Anisoptera (Odonata) larvae tended to be more numerous in benthic samples from fishless lakes than from lakes with fish, and their exuviae were significantly more abundant around fishless lakes . In most lakes, the assemblage was dominated by three species ; Leucorrhinia glacialis, Libellula julia, and Cordulia shurtleffi . In lakes containing white sucker, Catostomus commersoni, Gomphus spp . were most numerous . In the most acid fishless lakes, L. julia was uncommon, and L. glacialis was extremely abundant . In fishless lakes, numbers of Anisoptera larvae and exuviae were negatively correlated with pH, though species richness was positively correlated with pH . Exuviae of Zygoptera (Odonata) were more abundant around fishless lakes, irrespective of pH . Larvae of Limnephilus (Trichoptera) were most abundant in non-acid fishless lakes, and absent at pH<5 .2 . Abundances of Banksiola (Trichoptera) were negatively correlated with the pH of fishless lakes .