The effect of supplemental dietary Chlorella-extract on lipid mobilization in ayu Plecoglossus altivelis was investigated in terms of in vitro lipolysis in cell free system of intraperitoneal fat body (IPE). The lipolysis activity was measured as the amount of fatty acids liberated from IPF homogenate in the presence or absence of lipolytic hormones (adrenaline, noradrenaline, cortisol, glucoagon, vasopressin).