We report here the isolation of three isoforms of a novel C-terminally amidated peptide from the gills of red sea bream, Chrysophrys (Pagrus) major. Peptide sequences were determined by a combination of Edman degrada-tion, MS and HPLC analysis of native and synthetic peptides. Three peptides, named chrysophsin-1, chryso-phsin-2, and chrysophsin-3, consist of 25, 25, and 20 amino acids, respectively, and are highly cationic, con-taining an unusual C-terminal RRRH sequence.