The total lipid and fatty acid compositions of tissues and the stomach contents of three subtropical marine fish species, subfamily Caesioninae, Caesio diagramma and C. tile, and family Siganidae Siganus canaliculatus, were investigated to clarify the differences between these species. Triacylglycerols (TAG) were the dominant depot lipids of the three species, whereas wax esters were found as a minor component. In particular, muscle lipids were found to contain mainly glycerol derivatives such as TAG and phospholipids. The major fatty acids identified in the three species were 16:0, 18:0, 18:1 n-9, and 22:6n-3 (docosahexaenoic acid, DHA). In addition, noticeable levels of 16:1 n-7, 18:1 n-7, 20:4n-6 (arachidonic acid, AA), and 20:5n-3 (eicosapentaenoic acid) were found. DHA was the most abundant polyunsaturated fatty acid (PUFA) in the muscle and viscera lipids of the three species. The high DHA levels in the lipids of all the organs were found to be higher than those of the lipid extracted from the stomach contents of the three fishes. In addition, the specimens of S. canaliculatus contained significantly higher levels of AA in its tissues than did the other two species. A high AA content is unusual since such high levels of n-6 PUFA are rarely found in higher marine organisms. These levels may be due to its characteristic feeding pattern, because S. canaliculatus prefer and mainly feed on seaweed, which often contains high amounts of n-6 PUFA, such as linoleic acid (18:2n-6) and AA.

Laborator), ofLipid Chemisti:}{, IVbtional Research institute ofFZsheries Science, Ministt:y ofAgriculture; Ilorestt), and fiVsheries, 2-l2-4 fuku-ur¢ Kdn(zzawa-ku, Ybkohama-shi 236-864& .lapan

The lipid and fatty acid compositions in two edible subtropical algae (the brown alga Cladosiphon okamuranus Tokida and the green alga Caulerpa lentillifera J. Agardh) were determined to clarify their lipid characteristics and nutritional values. Glycolipids and phospholipids were the major lipid classes, with significant levels of triacylglycerols. Polyunsaturated fatty acids (PUFA) were the major fatty acids of both algae. The lipid class composition and major fatty acids were similar in both the algal species, irrespective of wild and cultured specimens. Typical n-6 PUFA, such as 18:2n-6 (linoleic acid) and 20:4n-6 (arachidonic acid), occurred in characteristically high levels in both of the algae. High levels of n-3 PUFA were measured in all lipid classes of both species without 22:6n-3 (docosahexaenoic acid), 18:3n-3, 18:4n-3, and 20:5n-3 (eicosapentaenoic acid) for Cl. okamuranus; and 16:3n-3, 18:3n-3, and 20:5n-3 for Ca. lentillifera. The finding suggests that the green algal species, which mainly biosynthesizes shortchain (C 16 and C 18 ) PUFA, differs from that of the brown alga, which is capable of biosynthesizing high 20:5n-3 levels. The PUFA levels in glycolipids of the two algal species comprised up to 60%, even though they are subtropical marine species. High n-6 PUFA levels in the algal lipids probably influence the significant levels of n-6 PUFA in herbivorous fishes, because the n-6 PUFA levels in marine fish lipids are generally undetectable or negligible.