Twenty-six taxa of fish were present in eighteen lakes in the southwestern quadrant of the Adirondack Park,
Herkimer and Hamilton Counties, New York. Species richness in the lakes ranged from 1 to 18 species. Here we assess
the condition and composition of the fish assemblages in lakes and compare in-lake changes in species composition over
an 80-yr period. To examine assemblage condition we estimated population size of species in the lakes using
mark-and-recapture techniques. To examine change in composition we compared the assemblage structure of these lakes
to that present in two previous surveys. Populations of all but the rarest species comprised several size classes, indicating
successful recruitment for all common species in all lakes. Most lakes support a rich, viable assemblage, although all but
one includes, and many are dominated by, exotic species. Although the lakes studied are in one ecoregion and often in the
same subdrainage, species composition differed among lakes and composition and abundance differed within lakes over
time. Assessments of the fish assemblage composition in these lakes, when compared over time showed marked
differences. These differences might be the result of several factors, but the presence of exotic taxa and extirpation of
native fishes can explain gross changes in fish assemblage composition in these Adirondack lakes.