Lethal and ‘disturbing’ temperatures in some fish species from lakes with normal and artificially elevated temperature

The mean lethal temperatures and ‘disturbing’ temperatures of 14 species of freshwater fish have been determined in field tests carried out on lakes unheated and heated by power‐stations near Konin. The relationships between these parameters and the acclimation temperatures of fish in these lakes are analysed in relation to roach Rutilus rutilus (L.), rudd Scardinius erythrophthalmus (L.) and perch Perca fluviatilis (L.) and compared with the other published data for these species.