During the years 1983 and 1984 collections of penaeid prawn postlarvae were made by Renfro net at night and day near the bar mouth during the four phases of the moon. An analysis of the data revealed that the number of postlarvae was more during the nights on 91 % of the observed days in the first quarter, 81 % of the days on new moon, 75 % of the days in the last quarter and only 60 % of the days on full moon. Number of postlarvae collected was usually more in the mornings of full moon rather than at nights. It was noticed that the day collections were generally richer during October and November in all the phases of the moon. Details of abundance of penaeid prawn postlarvae of various species in relation to diurnal and lunar phases are discussed in the paper.