The effects of in vitro exposure to lead ions Pb₂₊ at concentrations of 0.01–25 mg/l on the activity of intestinal mucosa glycosidases in fish with different feeding spectrum – planktophagous blue bream Abramis ballerus (L.), benthophagous bream Abramis brama (L.), roach Rutilus rutilus (L.), white-eye bream Abramis sapa (Pallas), ichthyophagous pike-perch Sander lucioperca (L.) and wels catfish Silurus glanis L. were investigated. Low sensitivity of glycosidases to the effect of lead Pb2+ in the investigated fish species was shown. The highest inhibitory effect was observed in bream, the highest stimulatory effect – in blue bream at the 25 mg/l concentration of Pb_{2 +} ions.