Seasonal abundance of the larvae of the milkfish, Chanos chanos (Forskal) in the Pullicat Lake has been studied with reference to the lunar phase, the time of the day and the tide during 1966-68 and correlated with surface salinity, surface temperature and rainfall.

The ingress of the milkfish larvae into the Pulicat Lake takes place continuously from February/March to October with two peaks. Quantitatively the peak in August/Septemberis more important that the one in April. The probability of each fish spawning in dependently of other in the population is perhaps responsible for the continuous larval occurrence over a prolonged period. A positive correlation of larval abundance with surface temperature in the range of 26.5 to 30.3^oC and an inverse correlation with rainfall has been established Surface salinity values during peak periods of larval abundance have been found to be 34.3 and 34.4%_o. Larval index of a particular year appears to indicate the success of the commercial fishery of the fish in the subsequent year.