A study on reproductive biology is much more needed for animal development. In pulmonates, most snails in the group are true hermaphrodites, so that the male and female reproductive organs are found in the same individual. Pulmonates are seasonal breeders. The climate of Maharashtra region is characterized by seasonal rainfall from June to October with a peak in the month of July and less from November. The gonadal index is varied in different season and high in monsoon season in most of the animals. The fecundity of snails fluctuated according to the species, environmental conditions, length, age, genetic potential, location etc. Maximum mean GI values (%) were observed during monsoon period whereas minimum mean GI values were observed during post-monsoon period for Indoplanorbis exustus. The breeding season of Indoplanorbis exustus was observed between July and October. July is considered the highest breeding month of Indoplanorbis exustus.