Kisspeptin, a hypothalamic neuropeptide, is the principal regulator of reproduction that acts upstream of gonadotropin-releasing hormone (GnRH). We have identified two kisspeptins (Kiss1 and Kiss2) and two kisspeptin receptor types (Kiss-R1 and Kiss-R2) in the teleost species. In the zebrafish brain, Kiss1 neurons are located in the ventral habenula, which project to the median raphe. Kiss2 neurons are located in the posterior tuberal nucleus and the periventricular hypothalamic nucleus. Recently, we have identified the potential role of habenular Kiss1 neurons in the modulation of serotonin (5-HT) and 5-HT dependent behaviours. We conjugated zebrafish Kiss1 peptide to saporin to selectively inactivate Kiss-R1-expressing neurons, which significantly reduced alarm substance (AS)-evoked fear response. These observations suggest that Kiss1 could be involved in social behaviours. On the other hand, the hypothalamic Kiss2 neurons together with Kiss-R2 expression in GnRH neurons have been viewed as potent regulators of reproductive function in fish. These results suggest independent roles for the two kisspeptins in reproductive and non-reproductive functions in teleosts.