The fish communities of all Austrian natural lakes ( n = 43) larger than 50 ha in surface area were assessed and the historical fish communities in c . 1850 were reconstructed. During the last 150 years, the fish communities of Austrian lakes have altered: in 49% of lakes at least one indigenous fish species, usually sensitive or small‐bodied taxa, is now missing. Conversely, in all but one of the 43 lakes the number of fish s...