Comparison of Dietary Carotenoids Metabolism and Effects to Improve the Body Color of Cultured Fresh-water Fishes and Marine Fishes

Effects of dietary carotenoids were investigated on the metaboβsm and body pigmentation of rainbow trout(Salmo gairdneri), masu salmon(Oncorhynchus macrostomos), eel(Anguilla japonica), rock fish(Sebastes inermis) and black rock fish(Sebastes schlegeli). Three weeks later after depletion, these fishes were fed diet supplemented with , lutein, canthaxanthin', astaxanthin or for 4 to 5 weeks, respectively. Carotenoids distributed to and changed in integument were analyzed. In the integument of rainbow trout. zeaxanthin, and canthaxanthin were found to be the major carotenoids, while lutein, isocryptoxanthin and salmoxanthin were the minor carotenoids. In the integument of masu salmon, zeaxanthin was found to be the major carotenoids, while triol, lutein, tunaxanthin, , and canthaxanthin were the minor carotenoids. In the integument of eel, was found to be the major carotenoids, while lutein, zeaxanthin and were the minor carotenoids. In the integument of rock fish, zeaxanthin, , tunaxanthin and lutein were found to be the major carotenoids, while , and astaxanthin were the minor carotenoids. Likely in the integument of black rock fish, , astaxanthin and zeaxanthin were found to be the major carotenoids, whereas , , lutein and canthaxanthin were the minor contributor. The efficacy of body pigmentation by the accumulation of carotenoids in the integument of rainbow trout and masu salmon were the most effectively shown in the canthaxanthin group and of eel, rock fish and black rock fish were the most effectively shown in the lutein group. Based on these results in the integument of each fish, dietary carotenoids were presumably biotransformed via oxidative and reductive pathways. In the rainbow trout, was oxidized to astaxanthin via successively isocryptoxanthin, echinenone and canthaxanthin. Lutein was oxidized to canthaxanthin. Canthaxanthin was reduced to via isozeaxanthin, and astaxanthin was reduced to zeaxanthin via triol. In the masu salmon, was oxidized to zeaxanthin. Lutein was reduced to zeaxanthin via tunaxanthin. Canthaxanthin was reduced to zeaxanthin via . and astaxanthin was reduced to zeaxanthin via triol. In the eel, and lutein were directly deposited but canthaxanthin was reduced to , and cholesterol lowering effect by Meju supplementation might be resulted from the modulation of fecal axanthin, astaxanthin and were oxidized and reduced to tunaxanthin via zeaxanthin. In the black roch fish, was oxidized to . Lutein was reduced to via . Canthaxanthin was reduced to via successively and zeaxanthin. Astaxanthin converted to tunaxanthin via isocryptoxanthin and zeaxanthin, and was reduced to via and zeaxanthin.