Effect of dietary astaxanthin on growth, body color, biochemical parameters and transcriptome profiling of juvenile blood parrotfish (Vieja melanurus ♀ × Amphilophus citrinellus ♂)

To investigate the effects of dietary astaxanthin on fish growth and body color, blood parrotfish juveniles were assigned to three groups: control (CL), fed a diet without astaxanthin supplementation for 12 weeks; coloration (ASTA+), fed a diet containing 0.45 g/kg astaxanthin for 12 weeks; decoloration (ASTA-) fed the diet supplemented with astaxanthin for the first six weeks and then the control diet for the other six. Our results showed that the specific growth rate showed no significant difference between ASTA+ and CL at weeks 3 and 6 and among ASTA+ , ASTA- and CL at weeks 9 and 12. The ASTA+ group showed higher skin redness at weeks 3, 6, 9 and 12 and higher yellowness at weeks 6, 9 and 12 than CL, and than ASTA- at week 12. The ASTA+ group had higher concentrations of astaxanthin, HDL-C and LDL-C than the CL at weeks 3, 6, 9, and 12 and than ASTA- group at weeks 9 and 12. By compared ASTA+ and ASTA- with CL, a total of 4250 differentially expressed genes (DEGs) were detected. Pathways, e.g., PPRA signaling pathway, fatty acid degradation, and ABC transporters, of DEGs involved in carotenoid deposition were enriched. DEGs involved in the absorption and transport (e.g., upregulated lpl and pltp, and downregulated stard7), metabolism (e.g., upregulated adh1 and dhrs7cb, and downregulated cyp7b1, dhrs11, and si:ch211-113j14.1), and deposition of carotenoids (e.g., downregulated apoa1b and apodb) might be associated with skin coloration. Overall, the results of this study could help to understand the biochemical and molecular mechanism of body coloration under the presence and absence of dietary astaxanthin in blood parrotfish.