AbstractThe LC50for 12… 96 h of a distillery waste water were determined forLebistes reticulatus, Lymnaea luteola, Lymnaea acuminataandViviparus bengalensisin the batch experiment with daily exchange of the medium. The sensitivity of the species increases in the given sequence with values of the LC50,96 hof 10.77 to 3.72 % proportion of wastewater in the medium. Compared with this, with values of the LC50,48 hof 14.06… 15.71 % after 48 h of exposure there is no significant difference in sensitivity, whereas after exposure for 12 and 24 h the sensitivity grows in the following order:V. bengalensis, L. acuminata, L. luteola, Lebistes reticulatus. Toxicity is obviously primarily determined by the sulphides; with increasing time of exposure also the suspended matter and other factors act toxica