Dietary arachidonic acid and the impact on growth performance, health and tissues fatty acids in Malabar red snapper (Lutjanus malabaricus) fingerlings

The present study assessed the growth, immune response and fatty acid composition of Malabar red snapper (Lutjanus malabaricus) fingerlings, as affected by dietary arachidonic acid (ARA, 20:4n-6). Four isonitrogenous, isolipidic and isoenergetic experimental diets were formulated with graded inclusion levels of ARA, at 0.05, 0.26, 0.47 or 0.65% of total diet. Triplicate groups of fingerlings (mean weight 5.9 g) were fed to apparent satiation twice daily for six weeks, until fish tripled their initial body weight. Growth, feed efficiency and survival of fish was not affected (P > .05) by dietary treatments. Based on the tested physiological response parameters, an apparent general improvement in fish health was noted, and in particular a linear positive correlation was observed between superoxide dismutase activity of fish and dietary ARA content. No differences were found in the total lipid content of liver, gill and muscle of fish fed the different diets, and their fatty acid composition reflected that of the diets, but with some notable variations. Independent of the dietary supply of EPA across the four diets, the content of EPA was significantly (P < .05) reduced in muscle and gill lipid of fish fed increasing dietary ARA levels. The present study suggested that Malabar red snapper fingerlings could benefit by the inclusion of some dietary ARA, however a trade-off with reduced EPA retention in some tissues is likely to occur and further studies are warranted to determine optimal dietary inclusion level of ARA.