“…In addition, all teleosts investigated have neuroepithelial cells in the gill that store 5-HT in vesicles (6,16,40,102). Furthermore, an isolated gill preparation can remove at least 40% of 5-HT from perfusate (66), and significant SERT mRNA expression has been measured in the gill (2,3,12,60), highlighting a potential role for the gill in 5-HT management. Metabolism of 5-HT into its main metabolite, 5-hydroxyindoleacetic acid (5-HIAA), by the gill, liver, kidney, and intestine (11,17,66,82) may also play a role in keeping plasma 5-HT levels low.…”