Mammalian studies have raised concerns about the toxicity of carbon nanotubes, but there is very limited data on ecogenotoxicity to aquatic organisms. The aim of this study was to determine eco-geno toxic effects of single walled carbon nanotubes (SWCNTs) in fresh water snail, Lymnea luteola (L. luteola). A static test system was used to expose L. luteola to a freshwater control, 0.05, 0.15, 0.30, 0.46 mg/L SWCNTs for up to 4 days. SWCNTs changed a significant reduction in glutathione, glutathione-S-transferase, and glutathione peroxidase with in hepatopancreas of L. luteola. Lipid peroxidation (LPO) and catalase showed dose- and time-dependent and statistically significant increase in hepatopancreas during SWCNTs exposure compared with control. However, a significant (p < 0.01) induction in DNA damage was observed by the comet assay in hepatopancreas cells treated with SWCNTs. These results demonstrate that SWCNTs are ecogenotoxic to freshwater snail L. luteola. The oxidative stress and comet assay can successfully be used as sensitive tools of aquatic pollution biomonitoring. © 2014 Wiley Periodicals, Inc. Environ Toxicol 30: 674–682, 2015.