When data are grouped into logarithmically equal size intervals, the standing crop of plankton in lakes forms a bimodal distribution with the peaks centered at ~10 and 500 μm equivalent spherical diameter. This "jagged" spectrum is quite similar to marine spectra characteristic of inshore habitats and offshore surface waters at high latitudes. It is different from the "flat" spectra characteristic of the surface waters of equatorial and subtropical oceans, and of all oceans at depth. The ratio of phytoplankton/zooplankton biomass in lakes ranges from 0.04 to 597.0, with most values falling within the range of 0.5–3.33 predicted for marine pelagic communities. Particle-size theory predictions of fish standing stock in two study lakes compare quite well to the actual fish biomass measured in the lakes. In contrast to the linear relation between phytoplankton and fish stocks predicted by the theory, a curvilinear relationship exists, suggesting that overall ecosystem productivity may influence particle-size patterns. To facilitate further comparisons between marine and freshwater ecosystems, we argue that additional information on the effects of spatial heterogeneity, nonliving particulate matter, automated measurement techniques, and benthic–pelagic coupling on particle-size distributions is required.