Age, growth and spawning season were studied in Sardinella sirm, S. albella, S. gibbosa and S. longiceps collected by gill nets in the coastal waters of Sri Lanka. Ageing was based on primary growth rings in the otoliths. The daily periodicity as verified for^S. sirm by comparing mean increase in number of rings and the time elapsed between a series of sampling dates. For the other species, the same periodicity was inferred from the similarity in structure to that of S. sirm. The species reach the following lengths after 1 year: S. albella, 12 cm; S. gibbosa, 13 cm; S. longiceps, 14 cm; S. sirm, 20 cm. The total life-cycles are 1—1.5 years. Apparently, all species reach maturity after about 1 year. There seem to be two spawning seasons per year. Estimates based on counting growth rings indicate that these coincide with the south west and north east monsoonal changes. This also agrees with the changes in maturity stages observed.