Lipid and fatty acid composition of normal and malpigmented Atlantic halibut (Hippoglossus hippoglossus) fed enriched Artemia: a comparison with fry fed wild copepods

Atlantic halibut larvae originating from a single spawn of one female and one male were fed either Super Selco(TM) enriched, enrichment-grade Artemia nauplii or extensively grown zooplankton. The feeding experiment was conducted in 1.5-m(3) outdoor tanks to evaluate if diet affected pigmentation. Pigmentation rates were found to be higher in the zooplankton-fed fish: 99.2% compared to 66.4% in the Artemia-fed halibut. Lipid and fatty acid analyses were performed on five malpigmented Artemia-fed fry, five normally pigmented Artemia-fed fry and 10 copepod-fed fry after 43 days feeding. Lipid class analysis was carried out on the eyes and carcasses of the halibut fry by HPTLC and densitometry. Fatty acid analyses of the same tissues were performed by gas liquid chromatography. Copepod-fed fry showed significantly higher levels of docosahexaenoic acid (22:6n - 3; DHA) than their Artemia-fed counterparts (54.9% and 15.8% DHA in eye phosphatidylethanolamine (PE), respectively). Ratios of DHA: eicosapentaenoic acid (20:5n - 3; EPA) were also higher in the copepod-fed fish: 11.1, 4.1 and 2.3 in, respectively, PE, phosphatidylcholine (PC) and triglyceride (TAG) in the eye lipid fractions of copepod-fed fry compared to 0.7, 0.3 and 0.1 in the same lipid of eyes of Artemia-fed fry. Within the Artemia-fed population, DHA and EPA levels were slightly, but significantly, raised in the eye PC fractions of normally pigmented fish compared to malpigmented ones. However, there was no significant difference in DHA:EPA ratios between normal and malpigmented fish fed Artemia. EPA: arachidonic acid (ARA) ratios were higher in zooplankton-fed fish but there was no significant difference in these ratios between normal and malpigmented Artemia-fed halibut. (C) 1998 Elsevier Science B.V. All rights reserved.