The ocurrence of 0+-aged fish was observed during 1992 in different habitats of the Lower River Rhine (km 815-856) and in two gravel-pit lakes connected with the main stream. In both waters successful reproduction was established by early developmental stages of a large number of resident fish species. The species composition in both riverine and lake habitats was similar. In the gravel-pit lakes, fry of all species was much more abundant than in the River Rhine. Thus, the lentic waters of gravel-pit lakes connected with the River Rhine represent highly productive spawning and nursery areas even for rheophilous species of fish, so that they may be of great importance for the recruitment of the River Rhine' s fish populations.