Regulation of gonadal sex ratios and pubertal development by the thyroid endocrine system in zebrafish (Danio rerio)

► Hypothyroidism skews sex ratios toward females in developing zebrafish. ► Feminization is reversible if euthyroidism is regained before gonadal sex commitment. ► Hypothyroidism delays puberty in male zebrafish. ► Hyperthyroidism permanently skews sex ratios toward males in developing zebrafish.