Effect of dietary canthaxanthin on the growth and lipid composition of red porgy (Pagrus pagrus)

A 24‐week feeding trial was conducted to study the possible effect of dietary canthaxanthin on red porgy growth and lipid composition. Two triplicate groups were established to test two experimental diets: (1) Control group fed a diet with no added carotenoids, and (2) canthaxanthin group (CTX100) fed a diet with 100 mg of synthetic canthaxanthin per kilogram of diet (CTX). Final and eviscerated weight were increased (P < 0.05) in the CTX100 treatment. The rest of growth performance parameters were not affected by the CTX diet. Whole‐fish total lipid content was decreased (P < 0.05) in CTX100 fish. In the liver, total lipids were not affected; however, saturated fatty acids in CTX100 treatment were significantly lower together with a higher n‐3 PUFA and a lower n‐6 PUFA, therefore increasing the n‐3/n‐6 ratio. Liver histology of CTX100 fish revealed decreased lipid vacuolization thus, significantly lowering hepatocyte area. In the muscle, total lipids were not affected. Similar to the liver, an increase of n‐3 PUFA and decrease n‐6 PUFA, led to a significant increase of the n‐3/n‐6 ratio. Concerning plasma, only total cholesterol (TC) was significantly affected by the CTX diet. Dietary canthaxanthin has an effect on red porgy lipid composition.