<p>Females of some animals often imitate mate choices of other females (models), which is called mate-choice copying. It can be predicted that many models provide the accurate information regarding better mates for mate-choice copying. In this study, we examined the effect of the number of model females on mate-choice copying in female guppies <i>Poecilia reticulata</i>. The first mate preference trial between the two males showed the original mate preference of the females. After the simultaneous presentation of different number of model females near the two males, the second trial was conducted to test mate-choice copying. The females reversed their mate preferences in the second trial and spent longer time with nonpreferred males in the first trial when they were close to one model than with preferred males that were close to no model, or two or three models. However, the females did not reverse their preferences after the presentation of three models near nonpreferred males and one model near preferred males. These results suggest that the optimal number of model females for mate-choice copying may be a single model, that is, simultaneous presentation of multiple models may suppress mate-choice copying, unlike previous studies using sequential presentation of multiple models.</p>