The article describes visually detectable anomalies in the structure of the crucian carpet, which make it possible to consider them as a reliable tool for operative ecological monitoring of aquatic ecosystems under the conditions of the anthropic press. The results of the conducted studies were tested in the course of the research "The Post-Mercury Control of Mercury Pollution in the Territory of the Former PO" Khimprom", and also appear to be important in assessing the environmental risk from groundwater pollution and adjacent water bodies in the northern industrial zone of Pavlodar.