Prolactin is a single peptide hormone secreted from the animal pituitary. It has a varietis thought to be one of the primary hormones regulating the balance of the osmotic pressure and ions. PRL exerts its biological effects by binding with the prolactin receptor (PRLR). Thus, our understanding of the physiological functions and mechanism of action of PRL relies on a thorough understanding of the PRLR. Prolactin receptor is a single . mRNA has been detected in several organs associated with osmotic regulation. Changes in the concentration of ions or salinity in the environment are associated with changes in the expression of , which is thought to represent the molecular mechanism of PRL regulation.and the tissue specific expression pattern in . The full-length cDNA encoding using homology cloning and RACE PCR. The terminal UTR, 1 821 bp encoding region, and 406 bp 3’terminal UTR. Alignment of the deduced amino acid sequences of the and those of other vertebrates demonstrated that they shared many protein features common in fish. Phylogenetic analysis revealed that the putative PRLR amino acid. For example, the PRLR amino acid sequence of shared 87.25% similarity. For other species, the similarity was 86.86%57.43%49.16%T. rubripesReal-time quantitative PCR suggested that the he PRLR transcript was detected at a high level in gill, kidney, and intestine suggesting that in is in osmotic regulation. in the gonads, liver, and spleen, suggesting that prolactin has a range of physiological functions in fish. Our results have provided valuable insight into the mechanisms of var.