Mating behavior plays a pivotal role in the survival and perpetuation of animal species. Vasopressin modulates social communication, social investigation, territorial behavior, and aggression, predominantly in males. Recently, knockdown or pharmacological manipulations of the vasopressin system impaired both courtship behaviors and success rates in fish. However, in contrast to its structurally and functionally similar peptide oxytocin, our knowledge of the roles of vasopressin neurons on mating behaviors remains very few and remains further elucidated. Nevertheless, the methodological approach employed in previous studies significantly impacts the ability to discern comparative details. Therefore, it is essential to meticulously examine the population of vasopressin neurons which are predominantly responsible for male and female reproduction in mating behavior. In the present study, we used zebrafish as animal model to study the specific population of vasopressin neurons in both male and female zebrafish after mating behavior. To quantify the neural activation of vasopressin neurons, we performed double fluorescence in situ hybridization (dFISH) targeting vasopressin neurons and the immediate early gene product cFos in adult zebrafish of both sexes after mating behavior. We quantitatively compared the counts of activated vasopressin neurons. Our data revealed that the quantity of activated vasopressin neurons in the mated females was lower compared to unmated females. Our next step is to characterize the vasopressin neuron subpopulation after mating, aiming to provide a thorough understanding of their features. Our study offers valuable insights into conserved vasopressin neurons in teleost fish, highlighting their role even in the absence of mate choice.