The Effect of Linseed Oil and Kelp Meal in Diets on Fatty Acid Profile of Rabbitfish Siganus Rivulatus

Abstract

Marine fish are an excellent source of dietary protein and omega-3 highly unsaturated fatty acids (n-3 HUFA). Various researchers claim that wild caught fish are healthier to consume than aquacultured fish. The assumption is that the diet of the wild fish is healthier and that translates to humans consuming the fish. The spinefoot rabbit fish is an herbivorous marine fish with a healthy fatty acid profile. Because diet can significantly influence the fatty acid profile of fish, we tested the effect of dietary non-marine lipids on rabbitfish proximate composition and fatty acid profile. Spinefoot rabbitfish juveniles were maintained in 50L glass tanks connected to a recirculating system. Fish were offered one of four dietary treatments with three replicate tanks per treatment. Three feeds were formulated to contain lipids with various fatty acid profiles. One diet was formulated with fish oil (Rich in EPA and DHA), one with linseed oil (Rich in alpha linolenic acid, ALA) and the third with linseed oil supplemented with DHA. Additionally, a commercial feed was tested as a reference and all results were compared to those of fish from another experiment that were reared using a high protein and lipid commercial diet. Results show that flesh of wild rabbitfish does not contain significantly more EPA and DHA than flesh of fish offered diets rich in ALA. Flesh of rabbitfish that consumed EPA and DHA in their diets contained significantly more of these two n-3 HUFA than flesh of wild fish. The present study demonstrates that consumption of aquacultured rabbitfish is as beneficial as, if not more beneficial than consumption of wild caught fish.

The Effect of Three Oils Sources in the Diets on the Performance of Siganus Rivulatus Fingerlings Cultured in Tanks

“…The results also showed that all diets used had good FCR values with a preference of linseed oil diet that reached 1.76. This value is better than those obtained in [22] study on S. rivulatus fingerlings reared in glass tanks (50 litres) with an initial weight of 4 g and 35% protein diet, where the FCR was 3.20 -3.80. This could be explained by the difference of fingerlings sizes, diets components and rearing conditions.…”