Changes in body condition and moisture ‘protein’ total lipid and ash content of the musculature in Puntius sarana and Sarotherodon mossambicus with maturation was studied in individuals obtained from the commercial fishery of the Parakrama Samudra, an ancient man-made lake in Sri Lanka. In S. mossambicus the body condition declined, in both sexes, with increasing maturity whilst in P. sarana the body condition improved with maturation until Stages IV/V and declined after spawning. The protein and total lipid content also showed marked changes with maturation, and at times differences were noted between the sexes of any one species. Generally, all changes in proximate composition with maturation were less well defined in the males in comparison to the females. In S. mossambicus (both sexes) the lipid content increased with maturation whilst in P. sarana the lipid content increased with the onset of maturity and declined from Stage III onwards, when deposition of yolk takes place, until spawning. Changes in protein content with maturity were also found to be different in the two species. The observations are discussed in the light of known knowledge on the breeding habits of the two species as well as on the different reproductive strategies opted for by P. sarana and S. mossambicus.