Technical Abstract: Leptin is a key pleiotropic cytokine involved in regulation of food intake and energy homeostasis in mammals. In channel catfish, the presence of a messenger RNA that encodes a leptin-like peptide (LLP) has been described. The objectives of our studies were to characterize tissue expression of LLP mRNA and changes in its expression after prolonged fasting and exposure to Edwardsiella ictaluri, (E. ictaluri), the bacteria that causes enteric septicemia in catfish. Channel catfish LLP gene was sequenced by genome walking and by 5’- and 3’-RACE. Channel catfish LLP gene contained 3 exons with the coding region located in exons 2 and 3. Nucleotide and putative amino acid sequence of the channel catfish LLP shared very low sequence similarities with leptin of other fish species or the mammalian leptin (24-49 %). The LLP mRNA expression was detected in various tissues including brain, stomach, spleen, heart, liver, and trunk kidney but was especially high in liver and trunk kidney. Expression of LLP mRNA in liver and brain was unaffected (P > 0.1) by prolonged fasting. Hepatic expression of LLP mRNA was elevated (P < 0.05) 2d after fish were exposed to E. ictaluri. In comparison, expression of LLP mRNA in trunk kidney and spleen was elevated (P < 0.05) 1d after E. ictaluri exposure. Furthermore, expression of LLP mRNA in trunk kidney was elevated (P < 0.05) 2d post exposure to E. ictaluri. Based on our results, the catfish LLP does not seem to assume mammalian leptin functions. Further investigations are required to clearly define the identity and functions of this transcript.