Somatostatin is a multifunctional tetradecapeptide which is involved in growth,development,metabolism and reproductive processes,via the specific seven α helical transmembrane G-protein-coupled receptors(GPCRs).This review briefly summarizes the progress of research on somatostatin and its receptors,with special emphasis on the intracellular signaling mechanisms mediating somatostatin actions on the regulation of pituitary growth hormone release in fish.To date,six somatostatin genes and four somatostatin receptors have been characterized in fish.The diversity of the somatostatin peptide family is due to the existence of multiple somatostatin genes as well as the tissue-specific differential processing of preprosomatostatin.The subtypes of somatostatin receptors are complex due to the polyploidization that occurred during fish lineage evolution.Information on the mechanisms of somatostatin suppression of GH secretion in teleosts is mainly derived from studies in goldfish,which indicates that cAMP formation,Ca²⁺ mobilization,and PKC activation may be involved in the mechanism through which somatostatin regulates GH secretion.However,the intricate web of intracellular signals is still far from being fully understood.In addition,species-specific differences in the mechanisms of GH release do exist in diverse models.The somatostatin genes,receptors and the mechanism of actions of somatostatin on pituitary GH release await further studies in teleosts.