We evaluated the factors regulating the secretion of digestive juices in fish. We cloned two intestinal hormone genes, gastrin (GAS) and cholecystokinin (CCK), from mandarin fish (cDNA consists of 581 bp nucleotides, including a 100 bp 5′ untranslated region (UTR), a 336 bp open reading frame (ORF) encoding 111 amino-acid residues, and a 145 bp 3′ UTR. The , consisting of 843 bp and 846 bp nucleotides, respectively. The gene consists of a 60 bp 5′ untranslated region (UTR), a 414 bp ORF encoding a polypeptide of 137 amino-acid residues and a 369 bp 3′ UTR, while the gene consists of a 112 bp 5′ UTR, a 403 bp ORF encoding a polypeptide of 134 amino-acid residues and a 332 bp 3′ UTR. The C-terminal of the GAS polypeptide has a similar octapeptide structure (DYQGWVDF/ DYLGWMDF) to that of CCKs’. The only differences occur Val₃ (GAS) and Glu₆ (GAS) are replaced by Met₃ (CCK) and Leu₆ (CCK), respectively. Real-time PCR analysis revealed that mRNA was primarily expressed in the intestine and pyloric caecum. The expression of CCK1 and mRNA was highest in the brain, but expression was also detected in intestine and pyloric caecum. Our results suggest that GAS and CCKs may be involved in regulating digestion, while CCKs appear to be associated with digestive and neurosecretory processes. The genes are constitutively expressed during larval development (022 days post hatching, DPH). Expression was higher during the early stage (4–8 DPH for GAS and 2–4 DPH for CCK), possibly linked to development and growth of the digestive tract, then gradually decreased to a stable level during the later stages of development.