Effect of varying dietary proportions of linseed and olive oils on fatty acid composition of Nile tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus) under aquaponics culture system

Abstract

This study evaluated the effect of varying proportions of linseed and olive oils in fish diets on the fatty acid 
composition of tilapia and catfish liver and muscles under aquaponics culturing system after 150 days of 
feeding period. Experimental diets contained linseed, sunflower and olive oils at a varying composition of 
between 0 to 100% and commercial diet as a control feed. Gas chromatography was used to analyze fish tissue 
fatty acid profiles. Significantly high composition of n-3 fatty acids were observed in tilapia fed diet 1 (p<0.05) 
with DHA (C22:6) being the dominant n-3 fatty acids at 12.2% and 10.8% in tilapia muscles and liver 
respectively. In catfish, muscle and liver had 10.4% and 9.7% DHA content respectively. The muscle 
accumulation of n-3 fatty acid was significantly higher than liver in both fish species and efficiency in their 
retention and relative resistance of DHA to β-oxidation in the fish muscles. In both tilapia and catfish, the tissue 
n-3 fatty acids decreased with the reduction in linseed oil proportion in the diet feed suggesting direct influence 
of dietary oil composition on tissue fatty acid composition.