There was no evidence, from this study, of accumulation of ARA
in the muscle tissue of the treated fish. The levels of ARA, the main
product of 18:2n-6 desaturation, were higher in the diets than in
the dorsal muscle of treated fish, where only very low or trace
amounts were found (Table 5). This observation confirms previous
reports that tropical wild fish, from both freshwater and marine
environments, include considerable amounts of ARA in their lipids
in contrast to intensively cultured fish (Karapanogiotidis et al.,
2006). Similar results for ARA were reported by El-Sayed, Mansour,
and Ezzat (2005), following studies on Nile tilapia broodstock,
where ARA was significantly lower in both dorsal muscle and in
eggs than in corresponding diets. In contrast, however Ng et al.
(2001) showed ARA levels of 2.3 g/100 g fatty acid) in muscle tissue
from red hybrid tilapia fed diets containing 10% cod liver oil.
Dietary ARA levels were not reported from this study, however.