Gonadotropin-inhibitory hormone (GnIH) is a novel hypothalamic neuropeptide which was originally isolated from the quail brain and known for inhibiting the secretion of gonadotropin (GTH) from cultured quail anterior pituitaries. GnIH participates in growth, reproduction, and food intake via the specific seven transmembrane G protein-coupled receptors (GPCRs). To date, GnIH was identified in several teleosts, including goldfish, zebrafish, grass puffer, tilapia and orange-spotted grouper. However, information on the studies of GnIH physiology are limited and contradictory in fish. The regulation of GnIH and its receptors as well as other roles of GnIH awaits further studies in teleosts. This review brifely summarized the progress of research on GnIH and its receptors, with special emphasis on the physiological functions of GnIH in fish and we hope this review will contribute to the futher studies.