THE LEVEL AND COMPOSITION OF FREE FATTY-ACIDS IN THE PLASMA OF FRESH-WATER FISH IN A POST-ABSORPTIVE CONDITION

The level and fatty acid composition of plasma free fatty acids (FFA) were determined in four important aquaculture teleost species: goldfish (Carassius auratus), common carp (Cyprinus carpio), rainbow trout (Oncorhynchus mykiss); and tilapia (Oreochromis mossambicus). Plasma was obtained from animals after a 3 day fast in order to study the mobilization of fatty acids in a post-absorptive condition. Plasma [FFA] amounted to 0.95 in goldfish, 0.77 in both carp and rainbow trout and 0.30 mu mol/ml in tilapia. The fatty acid composition was dominated by mono-unsaturates in goldfish and carp, whereas saturates were the main fatty acids in tilapia. The largest amount of PUFA was observed in rainbow trout (41%) which was considerably higher than ire the other species (27-29%). The interspecies differences of plasma FFA levels and patterns are discussed in relation to the site of lipid storage, mobility and other factors.