In the present study an attempt has been made to determine the breeding periods of 14 species of nematodes, three species of gastrotrichs and two species of copepods, based on the incidence of gravid females and the preponderance of juveniles in the samples collected and examined during the course of one year. Interesting correlation has been noticed between the data on the occurrence of gravid females and the incidence of juveniles in various samples. Based on their breeding periods these species have been classified into distinct categories.