Effects of <i>Tagetes erecta</i> on the Pigmentation of Large Yellow Croaker( <i>Larimichthys crocea</i> )

<i>Larimichthys crocea</i> (<i>L. crocea</i>), an important species in mariculture, is highly valued for its nutritional benefits, delicate flavor, and distinctive golden body, making it a popular choice among consumers. However, suboptimal breeding conditions and high stocking densities, often lead to reduced flesh texture and a deterioration in body color. Given the significant role body color plays in determining the commercial value of this species, this study evaluated the impact of various dietary supplements on color enhancement. One basal diet and three separate experimental diets were formulated: one supplemented with 200 mg/kg <i>Tagetes erecta</i> extract (2% lutein), one with 200 mg/kg astaxanthin (2%), and one with 200 mg/kg amaranth (<i>Amaranthus</i> spp.) leaf extract (85%). The results indicated that <i>T. erecta</i> was more effective in enhancing the body color of <i>L. crocea</i> than the other two supplements after 28 days of feeding, with the <i>a</i> ^<i>∗</i> value (red-green) 1.25-fold higher than the control group and ventral <i>b</i> ^<i>∗</i> value (yellow-blue) was significantly elevated (<i>p</i> = 0.028) compared to the control group. Initial mechanistic studies revealed that <i>T. erecta</i> enhanced body color through regulating carotenoid uptake and melanogenesis. These findings provide valuable insights for optimizing feeding strategies to improve the market appeal and commercial value of <i>L. crocea</i> in mariculture.