The sale formation of common carp, grass carp, silver carp, bighead carp and tilapia w ere studied by using the aliaarin red method. The first appearance of scales at a Total lngth of 16-19 mm, 17-19 mm, 21--32 mm, 26--31 mm and 10-13 mm respa for the 5 species of fish and the formation completed at 24-30 mm, 2-2$ znm, 47-55,48-55 mna and 19-21 mm total length respectioely.scales first appem,red along the lateral Iine all species which could be separated into categories according to the region o# first scale appearance and the pattern of scale dev elopment.commom carp, grass carp, silver carp and bigheadcarp, scales first appeared behind thH operculum, and developruent took place from anterior to posterior. In tilapia, scales first appeared on the caudal peduncle and developed anteriorly. The carps could be further subdivided, based on the detailed pattern of scale development, common and grass carp in one group, and silver and bighead carp in another.Regression of scale formation parameters upon fish length. and :age showed that the initiation and termination of scale formation as well as certain deiTelopmantal patterns were closely related. to body length, but insignificantly to age.Tha pattern of scale development not only reflects that growth law which is applicable to each species,but also reflacts the evolutionary relationships amom fish species.