The length-weight relationships of male and female Sarotherodon galilaeus of Lake Nasser Egypt were found to be isometric, whereas that of the combined sexes was allometric. Males were heavier per unit length than females. The condition factor revealed monthly variations and sexual dimorphism, but did not show any particular trend with the increase of fish size. The time of minimum increment of the annulus formation was found to be in January for males and in May for females and combined sexes. Male/female differences were recorded in the annual increments of length and weight. Comparisons of the results of the present work with those of other authors in different localities and times revealed year-to-year and geographical variations. Such comparisons also emphasized on the effect of eutrophication and pollution on the growth and age composition of S. galilaeus in some of the Egyptian lakes.